Monday, December 30, 2019

Converting digital color images into Black and White ~ back to basics with filters

After covering the color to black and white conversion process in a simplified manner I think it might be helpful to take a look at the very foundation of image conversions.  That is to say, how we as humans "see" or "experience" the relative color intensity as it relates to gradations of gray.

Setup -
  • Three color wheels illustrating different color principals organized into a single image
  • Rawtherapee used to process images through the "Black and White" tool
  • Gimp used to reorganize the converted images so the original color image is show side by side - so viewers can gauge the relative color "intensities"

Black and White Conversions -

Color image simply de-saturated -

Rawtherapee BW Conversion ~ Desaturation Only

As a first pass this isn't too bad.  If you like the results you can stop here and "call it good."

But as you can likely see, the dark blue areas, the reds, and greens in the upper-most wheel don't "feel" like the tones are correctly expressed in grays.  They are either too "light" to our eyes or too "dark."

So if the goal is to closely match how a color "feels" in gray relative to other colors then simply de-saturating an image might not "feel" right.

Conversion using luminosity values -

Rawtherapee BW Conversion ~Luminence Equalizer

The subtle blue values seem to convert rather better in this technique than with simple de-saturation.  However, the greens, yellows, and reds still don't "feel" right.


Conversion using the Channel Mixer (no filter) -

Rawtherapee BW Conversion ~Channel Mixer Normal Contrast 5400 Kelvin

To my eyes this is an improvement over the luminosity and de-saturation processes.  There is more subtle tonal variations between the colors.  Yet, the conversion still feels like it's missing a bit of "pop", which is to say it "feels" as if there might not be enough separation between the subtle shades of color as they are expressed in gray.


Conversion using a Channel Mixer Yellow Filter -

Rawtherapee BW Conversion ~ Channel Mixer Normal Contrast Yellow Filter

The classic approach in silver halide films was to take a panchromatic black and white emulsion and to shoot with a yellow filter.  The idea was to find a way to make an image "pop."  There are even lenses known to have properties that helped make an image behave this way.  The Takumar 50mm f/1.4 screw-mount lens comes to mind.  The lens coatings had a yellow cast.

In digital we can perhaps begin to understand why this approach usually worked for us old film photographers.  Take a look at the image above.  It's starting to "pop."  The colors converted to grays are beginning to "feel" more or less correct.  The only problem I see is that the reds don't yet "feel" right and the yellows are a little too "hot."


Conversion using a Channel Mixer Yellow-Green Filter -

Rawtherapee BW Conversion ~ Channel Mixer Normal Contrast GreenYellow Filter 5400Kelvin

Goal! Suddenly it feels as if we've found a very good solution. 

Applying a Yellow-Green filter in Rawtherapee we see the various color intensities expressed as clearly delineated grays.  The only comment I would make is that perhaps the blues and teals could be just a touch darker.  But this is easily fixed by gently darkening in these two colors prior to conversion to black and white.


Other Filters -

Early photographic emulsions captured only the blue end of the visible spectrum of light.  This is why all early photographs show skies as white or very light.  It wasn't until the advent of panchromatic emulsions that skies in photographs became what they are today.

If you want to emulate early emulsions you can start by using a blue filter.  Here is how Rawtherapee expresses this filter.

In the early part of the 20th century,  Saint Ansel made a fine image of Half Dome in Yosemite Valley.  He wrote about the making of this image and how he felt he'd hit upon a good solution to make the image "pop."  He used panchromatic film to capture the full spectrum of light and a red filter to darken the sky.

So in this spirit, sometimes a red filter is the right tool.  Here is how Rawtherapee expresses this filter.


In closing I can't stress strongly enough that people should do their own image conversion comparisons using the tools they normally use to process their images.  I have found that different tools implement black and white filters differently.

------------------
For further reading as additional background on the topic of how we "see" things in Black and White, please refer to this.

Thursday, December 26, 2019

Thirty Years of Looking at Photographic Gear and Lenses ~ Summary of Findings

Musee d'Orsay ~ Paris, France


If you've read my scribblings and blather from the early days you know that I've been poking at this subject for over 30 years.

I tend to put a lot of, dare I say too much, energy into photography, camera equipment, and image processing.  In my defense, however, every day seems to bring some new understanding or some spark of insight.

It recently dawned on me that there might be a simple short summary of my "findings."  I'm not sure how this would help, but, I think it might be worth the effort to articulate a few things.  Years and years of cogitation boiled down to practically nothing.  Just a few sentences.

As someone famously said, make things as simple as you can, and no simpler.  This is my attempt to be simple and no simpler.  In this light (ahem), I feel confident enough to articulate three basic, foundation insights into the tools of photographic image creation.

Here they are -
1) The limiting factor for sharpness and resolution in an image is not the lens.  The limiting factor is, instead, the light sensitive material used to capture that image (film or digital sensor).   

NOTE: Most lenses, regardless of focal length, aperture, and coverage that I have owned, held, looked at and used, from small through ultra-large format, easily out-resolve whatever is capturing those photons of light.

 

2) The "interesting" thing about lenses is not how sharp they are (see #1 above), but how they transition into and out of focus.  

NOTE: This is where some of the real "magic" in a lens can be found.  It will show in the final results, whether we understand and recognize this or not.


3a) When shooting film - expose for the shadows and process for the highlights

3b) When shooting digital - expose for the highlights and process for the shadows

There it is.  My "findings" in a 30 year nutshell. 

I hope this helps.

Sunday, December 22, 2019

Flickr ~ the long slow goodbye?

Lens Stories ~ Sony A6000 + Nikon Nikkor 20mm f/3.5 UD pre-Ai


Something kept me awake last night.  I thought a lot about the current pace of change in the online world.
 
Earlier this month I received an email from Smugmug, the current owners of Flickr.  They were offering a discount to open a Smugmug account.  I thought that was curious since I thought I was already part of the Smugmug Group.

Then came an email from one of the Big Wigs at Smugmug.  It sounds like Flickr is failing to meet financial expectations.  As a last gasp, the new owners of Flickr are pleading with users to buy more subscriptions.

I've been a Flickr member for 15 years and am a rather heavy user.  I have over 28 thousand images posted and 13 million views.

My use pattern quickly developed in the early days.  Flickr hosted everything I wanted to share.  It has never been a backup site (a massive image cloud, if you will).  Rather, it was a site for publishing finished works and the make connections with like-minded image-making crafts/arts-people.

My blogs, Facebook, Tumblr, Instagram, and PX500 pages all pointed to or originated from my Flickr account.  I have links to Flickr sprinkled nearly everywhere I've had an online presence.

Over time, however, my online participation changed.

I closed and deleted my Facebook account after I realized Zuckerberg and his management team were more interested in selling out than they were to expressing, enabling, or extending truth telling, truth sharing of democratic impulses in the country they are incorporated in.

By extension, because Facebook owns Instagram and has an even more onerous business style, I cancelled them, too.  It wasn't just the personal information selling that concerned me, it was their loose interpretation of copyright protections.

Similarly, I deleted my Tumblr pages after Yahoo sold to Verizon and became "Oath."  Tumblr had been a free-wheeling environment where I could find just about anything image-related.  There were sometimes interesting image ideas that I could borrow from.  But with the Verizon acquisition came a Puritanical lock-down on certain image forms thus casting out any art expression management didn't like.  My image never tended toward anything controversial, but it was the principal of the matter.

At one time it seemed like PX500 was doing good things.  They had their image sharing platform and they offered guidance on creating good images as well as conducting interviews with prominent photographers.  Two things happened in similar time to cause me to close my accounts there, too.  First was the huge security breach that they failed to tell users about for quite a long time.  Second was sale of PX500 to the Chinese.  That did it.  I was done.  Out of there.

Now comes word that Flickr is not meeting financial goals.  The implication is that the platform may not be around much longer for paid subscribers.

This leads to a number of questions -
  • What will become of the images I've posted to Flickr?
  • Will the site simply go "dark?"
  • Will Smugmug provide a migration path to their other platform?
  • What do I do about all my Flickr links that are embedded in things I've written
  • How do I manage links and information on sites I have contributed to but have no control over where my contact information is published?

Most of this I can manage, I hope.  Yet this doesn't really address my concern for where to share my images.

Should I move to Smugmug and bet against history that they continue to live?  Or is there another platform I haven't already considered?  Or should I just pull the plug and "go dark?"

Happy Holidays!  It's been an interesting year.

UPDATE: The CEO updated his comments. 

UPDATE2: The CEO added yet another comment.

Thursday, December 12, 2019

Out of Focus Rendition ~ a summary of thoughts and findings

What a year it's been.  The end result being that I have moved decisively to considering more than just lens resolution when thinking about commercially available optics for photography.

With the help of some comments made over on DPReview (which, unfortunately, I can no longer find) and Nikon's "Thousand and One Nights" series I have had the opportunity to explore something that truly distinguishes one lens from another.

I continue to poke at the topic in spite of the mobile phone having become the primary image maker for the vast majority of people.  Thus far I feel that phone camera images have a "synthetic" feel to them.  They still feel much like the early point and shoot camera images did.  They tend to have a "water-color-y" look and feel, but this is quickly changing.

I don't have the budget to rush out and buy the latest gadget, which encourages me to continue to explore interesting properties of "old school", "traditional" photographic equipment and, of course, lenses.  For the moment I am sticking with stand alone cameras with APS-C sized sensors (Sony NEX and Axxx) and old manual focus lenses (Nikon, Takumar) and, much of the time, focal reducers (Lens Turbo II). 

This year I learned the most interesting thing about commercially designed and manufactured lenses is not how sharp they are.  Sharpness in the purest sense of the word is rather trivial to achieve.  Lenses more than one hundred years old are quite often sharp.

Other optical properties are at last as important as resolution.  Field flatness, chromatic aberration control, and distortions are lens faults commonly found, even in modern optics.  While processing can do nothing to correct field flatness issues, distortions and chromatic aberration controls are usually just a short step away from being corrected in software (either in-camera, or during processing on a computer).

As for field flatness, I recently learned a lot more then I ever knew.  Fixed focal length lenses are often touted as having flatter fields than zoom lenses.  I have found it depends on the lens and distance to the subject, but to be, in the broad sense, true.  I have several wide angle fixed focal length lenses that suffer from as much field curvature as a few zoom lenses I have.

Conversely, zoom lenses are frequently criticized for being "soft" in the corners.  But this depends on where you focus the lens.  Most of us focus a lens near the center of the field.  As an experiment try focusing a zoom lens in the corner and you will likely find that it actually is quite sharp there.  The effect is a clear demonstration of field curvature and not of a zoom lens being "soft".

In all my years of looking at this only one family of lenses ever tested soft when I expected it to be sharp.  I have owned far too many of these thinking I'd somehow picked up "bad" copies.  The lens is the famous but utterly uselessly soft down to f/8 Zeiss Tessar 50mm f/3.5 or f/2.8.  I paid 7USD for the last copy I had and now know what I know and, well, I will never buy another, no matter how cheap.

Tessars don't need to be soft, and in fact most aren't. I had a 200mm Nikkor-M f/9 large format lens that was razor sharp from wide open.  Similarly, every single Kodak Commercial Ektar f/6.3 (all tessar formula lenses) I ever owned and used was incredibly sharp, again, from wide open.  So the Zeiss 50mm Tessar problem wasn't with the optical configuration.  It was something else.

Related to famous marque identification is the phenomenon where someone "in the know" claims some lens or other to be an un-discovered gem.  It's crazy watching how the market responds like sheep in a herd.

Nearly anything labeled Zeiss or Leica appear to "hold their value" on the open market.  It doesn't seem to matter if the lens is actually "good" or not.  No matter.  The brand etched onto the lens barrel seems one factor that drives pricing.

Then there are lenses which have special "optical effects."  Petzval lenses went from relatively cheap and unknown to highly valued and expensive when someone talked up the "swirly" out of focus rendition.  I watched as an American whipped out a rather impressive stack of Euros at a French photo swap to pay a German for a small collection of brass-era lenses, some of which were Petzvals.

Similarly, the Helios 40 85mm f/1.5 "Sonnar" design Russian lens has the power to drive crazy prices.  True Petzval lenses are rare and might be worth what one pays, but the Helios?  Really?  There are a ton of them out on the market today but no one is asking the less than 100USD they might have gone for before they were "discovered."

Then there is the "soap bubble bokeh" craze that, even now, appears to be raging out of control.  Certain lenses are so expensive that it takes my breath away.

The herd is "all in," as they say.  And for what?  A three element lens that was deliberately designed to give over-corrected spherical aberrations behind the point of focus so that one or two aperture clicks down from wide open the thing would be acceptably sharp?  Yikes!  If what you really want is "soap bubble bokeh" I can point you to three lenses that might set you back all of 25USD that still do that trick.  But find one of those "special" lenses and you might pay a bunch of money for it.

No.  I try to avoid herd-thinking and wallet-denting pricing for an imaging fad.  None of those things are all that interesting to me.  Besides, my fixed income life has put a halt to chasing highly touted optical "pixies."

However, the thing I find most interesting about lenses is how they transition from in-focus to out-of-focus.  That is where the optical "magic" lay.  That is where lenses can distinguish themselves, one from another.  And like field flatness, there are no "corrections" for this in software.  The effect is inherent in the lens, whatever it is.

Optical formula has little or no effect on out of focus rendition.  This includes Plasmat, Planar, Xenar, Xenotar, Tessar, Ektar, Artar, Sonnar, Gauss Wide Field and many many other basic, and now classic optical formulas.  Lens element layout is not a real, nor very useful predictor of out of focus rendition.

I smile when I read marketing literature claim such and such a lens is "classic Sonnar," for example, and such and such lens will give the "classic Sonnar" out of focus rendition.  Such claims are wildly misleading.

Returning to my large format lens example, the Nikon Nikkor-M 200mm f/9 tessar formula lens was not only sharp from wide open, but the out of focus rendition was creamy beautiful.  Not so on either account the poor old Zeiss Tessar 50mm previously mentioned, which is famously "soap bubble bokeh" over-corrected for spherical aberrations behind the point of focus.

How spherical aberrations are treated in the out of focus areas of an image are determined by the lens designer and the calculations they make, in the lens curvatures they specify, and not by the number of elements nor the configuration they are arranged in.



Coming back to the practical, experiential world, to my eyes, I find I prefer -
  • Neutrally corrected spherical aberration lenses for most subjects including street scenes and transportation (cars, trains, motorcycles)
  • Under-corrected spherical aberration lenses for portraiture, still-life, and gardens (trees, shrubs)

My current favorite neutral spherical aberration corrected lenses include -
  • Nikon Micro-Nikkor 55mm f/2.8 and f/3.5 
  • Three Nikon zoom lenses
    • Nikon 75-150mm f/3.5 E-series 
    • Nikkor 80-200mm f/4.5N Ai 
    • Nikkor 100-300mm f/5.6 AiS

My current favorite under-corrected for spherical aberration lenses behind the point of focus include -
  • Nikon Nikkor 50mm f/1.8 AiS
  • Nikkor-P 105mm f/2.5
  • Nikkor 85mm f/1.8 H, HC, or K

If I had unlimited resources and access to other lenses from other manufacturers it would be interesting to see how they compare to my current collection of Nikkors.  Alas, such things must be left to others interested in the topic or for me in another lifetime.


Parcs Ch√Ętenay-Malabry

Tuesday, December 10, 2019

What to pack and other First World problems...

... so... we're packing our things in preparation for leaving Paris for the winter.  I never thought I'd see the day when I, too, could be considered a Snow Bird by flying (as it were) south for the winter.  But there's the truth of things.

A couple friends asked which cameras I would be taking.  My answer was this -

I ran a test of my lenses to see how much I "gained" in terms of IQ by going with the old Nikkors. 

Alas, It's really difficult to tell much difference. I know where to look so I know the old lenses out-perform the new stuff. But it's not really significant.

Particularly this beautiful 50mm f/1.8 SEL (APS-C only) Sony that I have. It turns out, she's a 'beaut. 

Just one 20mm Nikkor UD f/3.5 out-weighs an A5000 + two AF plastic lenses. Weight. 

And I'm getting old. So... the AF lenses are what I'm taking. The Nikkors I'll continue to use, as you say, around town and close to home.

Sony NEX-7 "walking around" kit

I wrote too soon and promised things that will never ever come to pass.

A little thought came when I looked more closely at the Out Of Focus Rendition of the Sigma 30mm f/2.8 EX DN E I was considering taking.  Frankly, the OOFR is scary bad when compared against a Micro-Nikkor 55mm f/2.8 Ai.  Looking at some of my recent work with the lens convinces me of the Micro-Nikkor's brilliance in separating a subject beautifully from the background.

At which point I felt the Sony A5000 with the Sony 16mm f/2.8 SEL, the Sony A6000 with the gorgeous Sony 50mm f/1.8 SEL OSS, and the Sony NEX-7 with a Lens Turbo II focal reducer and the Micro-Nikkor 55mm would do the trick.

Slippery Slope Alert: 
Since the Lens Turbo II is now part of the "kit", why not, I asked myself, carry not only the NEX-7 with the aforementioned Micro-Nikkor and for just a bit more weight carry the lovely Nikkor-O 35mm f/2 that I recently picked up for a song along with it?  That way I could carry one workhorse camera along with a slightly wide and slightly long lens.  Maybe I could leave the Sony A6000 at home?

Er.  Right.

The NEX-7 is new to me and I'm not sure I'd put full faith and trust in it.  Particularly since we'll be gone for three months.  Anything could happen, right?  Ah, heck!  The A6000 is small and light, so just put a body cap on it and take is as a backup camera.  Just in case, and all that.

You see where this is headed, right?  Yes.  I was sure you would.  But.  It gets worse.

Quickly reviewing the list of places we want to visit I see several art communities, small villages, a couple car and motorcycle events, and, of course, Monaco.  Indeed, the NEX-7 could do well in these situations.  The Micro-Nikkor could practically live on the camera.  Or maybe the Nikkor-O could do most of the imaging duties.  No worries.  I'd have both with me.  All is good... um... hold on...

We want to visit Menton during the Orange Festival (which is at the very same time as the Carnival in Nice).  Part of the Menton partying includes an orchid show.  Hmmm... I've been wanting to shoot some flowers using... oh gawds... here we go... some more...

Now I'm at the point of taking the A5000 with the ultra-wide angle pancake lens.  It's super light and will be nice when I photograph cars from above.  I'll have the NEX-7 with the focal reducer and the two lenses, 35mm and 55mm.  The A6000 will be sitting there as a backup, so why not mount up a wonderful Nikkor-P pre-Ai 105mm f/2.5 and take the little Nikon 12mm extension tube, too?

There.   Everything is covered.  All imaginable situations (based on prior history of being on the Riviera during the winter) have been considered.  Alas, there are a few more days before we leave and maybe a new thought will come to mind?  I sure hope not.

That we all should have such problems, right?

Sony NEX-7 "walking around" kit

Wednesday, December 04, 2019

Tones and Tints ~ Creating Look-Up Tables (LUTs) for use in RawTherapee

Background ~

About a year ago I started to have trouble with a hard-drive that was failing on my super-fast laptop.  My father's HP (different model than mine) did the same thing a year earlier.  Maybe HP laptops overheat the hard-drive?  Or perhaps they had a long run of "bad" drives?

Fed up and disgusted with how Microsoft Windows rots from the inside out and how HP buries it's hard-drives deep into their laptops, I jettisoned the whole thing and returned to my roots.  One of the things I did in my work life was bring Linux to software developer's attention.  In this case it was easy for me to grab a slow, under-powered, and unused Dell laptop and load it with Linux and have it perform decently.

I have used the Gimp for over fourteen years and am used to Open Source Software.  The biggest restrictions for me with the Gimp is it's inability to open RAW files and to work in anything but at an 8-bit color depth.

The Gimp offers at least two useful approaches to change a base image's colors, "Sample Colorize" and a wide range of options implemented in G'Mic (Color Presets, Color Grading, Film Emulation). 

Around the time my Win10 HP box was causing trouble I downloaded RawTherapee.  It opens a vast variety of RAW formats and provides a default color depth of 16bits.  While at first it seemed difficult to understand and use, I quickly caught on.  Naturally one of the first goals I was to emulate film tones in the RawTherappe 16bit space.

Fortunately G'Mic has a set of emulations for RawTherapee.  I installed them, but instantly wished for more.  There are some really interesting LUTs in G'Mic Color Presets on the Gimp and over the years I have created some nice color samples from beautifully tinted black and white photographs.  These are what I wanted over in RawTherapee.


LUT creation and transfer ~ 

Using the (privacy) Force I did a bit of research and quickly understood how I could transfer some of the Color Presets and film emulations I like as well as my black and white tints from the Gimp into RawTherapee.   

I used the following materials -
  • Linux Mint OS (any Linux distribution should do - and something similar should be achievable with Windoze and Apple)
  • A copy of the base 12 or 16 bit HaldCLUT image to work from (the LUT base)
  • the Gimp (in my case v2.10)
    • G'Mic installed (the latest version)
    • black and white Sample Colorized step wedges
  • RawTherapee
    • G'Mic film emulations (used for its directory structure if you don't want to create your own - besides the G'Mic film emulations are a pretty nice place to start)

To transfer LUTs or Film Emulations from the Gimp -
  • Open an unaltered base LUT in the Gimp
  • Open G'Mic -> Color -> Color Presets
  • Apply the desired Color Preset to the open LUT image
    • NOTE: I like to keep the default layer active and have G'Mic write the changed color pattern as a new (inactive) layer.  That way I don't have to destroy and re-open the base image.  
  •  Keeping G'Mic open, move to the Gimp after the new LUT layer is available and save the Color Preset modified layer named as something meaningful to you and in .png format (this is essential)
  • Repeat these last two steps for as many Color Presets as you would like to transfer into RawTherapee

To create black and white tint LUTs in the Gimp -
  • Open an unaltered base LUT in the Gimp
  • Open Color -> Map -> Sample Colorize
  • Sample Colorize the open LUT image using a BW tint step wedge
    • NOTE: I like to make a copy of the base as a new layer and Sample Colorize the new layer.  That way I don't have to destroy and re-open the base image.  
  • Save the Sample Colorized LUT layer named as something meaningful to you and in .png format (this is essential)
  • Repeat these last two steps for as many Color Presets as you would like to transfer into RawTherapee

Making these updated LUTs available in RawTherapee -
  • Verify the location of the LUT directory you have pointed RawTherapee to
    • If you're not sure where the film emulations are found, open RawTherapee -> open Settings and note the LUT directory location
  • Using a terminal or, better, Folder view, Change Directory to the LUT directory and note there are (at least) two sub-directories inside the HaldCLUT directory
    • Color
    • Black and White
  • Inside each of these directories are further sub-sub-directories.   At this point you can choose an existing sub-sub-directory, or, as in my case, create new sub-sub-directories using a meaningful naming convention (such as GimpLUTs or anything that differentiates your new LUTs from the existing collection)
  • Copy your newly created .png LUTs from their current locations into the new RawTherapee directory structure locations.
  • Restart RawTherapee if it's still for some reason open
  • Go to Film Emulations and verify your new LUTs are where you expected them to be
  • Open an image file and apply your new LUTs to verify they look like they did in the Gimp
If you are fluent in Linux system and application management you will quickly recognize there are several ways of achieving similar results.  What I've tried to provide here is a recipe based on an existing directory structure, that being provided by G'Mic.  Of course you can create your own directory structure and forego the use of G'Mic altogether.  Just point RawTherapee at your top directory and the system should be able to understand your intent.

Sunday, December 01, 2019

A little something called Super-resolution [part deux]

After looking at handheld super-resolution image making a friend suggested that image stitching, rather than image stacking, could lead to useful improvements in image file size.  So, naturally, I had to take a closer look.

Before we look at the results, let's compare the two approaches.

Image Stacking for Super-Resolution -
  • Shooting handheld
  • Fire-off a half dozen images of the scene using a high-speed multiple exposure mode
  • In processing -
    • Align the images
    • Stack the images as layers in PS or Gimp
    • 2X bi-cubic 600DPI (minimum) up-rez every image
    • Set the opacity of each layer
    • Flatten the image
    • Apply an Unsharp Mask of 2 pixels
Pros -
  • Image noise is reduced significantly
  • Light/Dark transition zones are smooth and "creamy"
  • 2x up-rez gives a somewhat useful, if not exactly brilliant, increase in viewable detail
  • If all else fails, at least there is an image to begin with, up-rez'd or not.  

Cons -

Image Stitching for Super-Resolution -
  • Set exposure to something at accurately expresses highlight and shadow detail - use this combination of aperture, shutterspeed, and ISO for taking all the "section"
  • Shoot small-ish "sections" of the scene where images sequentially overlap eachother, making sure you've covered the entire scene (see: Breznier Method)
  • In processing -
Pros -

Cons - 
  • Images need to be planned with final images visible only after processing - which means it really helps to "pre-visualize" a scene
  • Depending on the software and accuracy of shooting image "sections" there may be distortions (example of failing to accurately rotate the lens around the nodal point)
  • Limited to static subjects
  • Slow setup time - suggest manual exposure metering to help the "sections" stitch correctly and to keep the overall final scene exposure even and correct
 

Comparison of Resultant Images -

[If you click on the image it'll take you to the Flickr hosting site. Once there, look at the file at full resolution. In many cases the differences between lenses is small and likely can't be seen until you take a squint at the comparison at 100 percent.]

Super-Resolution ~ comparing stitched and "cubic uprez"


The obvious conclusion is this - even though the stitched image is 1400 pixels shorter in the long dimension than the stacked up-rez'd image, the stitched image clearly resolves small details better than the stacked image.



My friend is, of course, correct.  Check out the section titled "4-Way Focusing Rail..."  The image stitch approach can be very nice indeed, but only if you plan ahead.

Wednesday, November 27, 2019

Lens Stories ~ Nikon Nikkor 20mm f/3.5 UD pre-Ai

The gifts keep coming.

Lens Stories ~ Nikon Nikkor 20mm f/3.5 UD pre-Ai

In the box along with the Sony NEX-7 my friend sent a Nikon Nikkor 20mm f/3.5 UD.  I was surprised, pleased, and, of course, very interested to see how it performed.

Historically, Nikon had earlier designs for a 2,1cm lens.  Those were symmetrical and the rear element set recessed deeply into, first, Nikon rangefinder camera bodies and later the Nikon F SLR.  In the case of the SLR the mirror had to be mounted up and out of the way so the rear element set could be properly positioned, thus nullifying the benefits of being able to look through the lens.

Thinking about it for a moment, the 20mm f/3.5 UD I was now holding represents Nikon's first strongly asymmetrical ultra-wide angle lens designed specifically for the Nikon F SLR.  For its time the lens would've been rather unique.

Lens Stories ~ Nikon Nikkor 20mm f/3.5 UD pre-Ai

Off to beers with a friend one day I took one of my trusty Sony NEX-5T cameras (I have far too many of these because, well, they're cheap now) with a Lens Turbo II focal reducer and mounted the old Nikkor.  The first thing I noticed was just how large the 20mm Nikkor is when used on a very slim, very small APS-C Sony mirrorless camera.  The next interesting thing I would notice had to wait until I returned from the pub.

One of the images that I'd taken had deliberately included sections of strong daylight highlights and deep pub-interior shadows.  The (now) small 16mpixel sensor is well known for it's long 13EV dynamic range.  The newer 24mpixel APS-C Sony sensors only slightly extend the range to 13.4EV (NEX-7).  So this, to me, means the old sensor will continue to perform very nicely for much of the kinds of photography I tend to do.

Liking fields of subtle grays I am pleasantly surprised by the detail and "creaminess" of the image I took of my friend.  As you can see, there is detail deep into the shadows and the highlights roll off nicely, just like when using old silver halide film.

The lens appears to produce little to no flare, which is quite remarkable considering the age of the optic and the fact it is only single coated.  It is sharp from wide open. 

I think this lens is a "keeper."

Lens Stories ~ Nikon Nikkor 20mm f/3.5 UD first light

Thursday, November 21, 2019

Camera Story ~ Sony NEX-7

A friend sent me his "old" Sony NEX-7.  Such a gift this is.  Such a gift.

Lens Stories ~ Sony NEX-7

My friend's first NEX-7 had died a mysterious and sudden death.  So he went down to the local camera store and picked up a nice used example as a replacement.  This second NEX-7 is the one he sent me.

I really like how Sony implemented the "rangefinder" EVF in the upper left-hand corner of these cameras.  In bright sunlight I can see what I'm focusing on and my "hit rate" is much better than with the non-EVF NEX-5T or A5000 camera bodies that I also use.

The first thing I did after receiving the camera was to check that the sensor was clean, and it was.  Then I took some photos and then applied black tape to "blacked out" the make and model information.  I like my cameras appearance better when I do this.  Lastly, I opened an instruction manual and read through how to set the functions and dials and wheels.

It is easy to see how similar it is to the more recent Sony A6000.  The controls layout, the overall size and weight of the cameras are nearly the same.  There is a strong family resemblance between these two. There are a couple minor differences (such as an AF mode control switch) between the NEX-7 and A6000.

Another difference is the Sony NEX-7 dual wheel control.  I think they called this "tri-navi", or something like that.  This is different from any Sony camera I've used.  There are two programmable wheels along the top back edge.  The default setting has the right wheel modifying the exposure value for setting under/over-exposure.  The left wheel is dedicated to aperture, shutter speed controls.  Then there is the role of the (unmarked) "function" key and how it is programmed.

Lens Stories ~ Sony NEX-7

After fiddling around with this for awhile it all seems rather complicated to me.  I can barely keep straight the menuing systems change that took place between the NEX-series cameras and the newer A-series.  When in a photo-shoot I find myself checking the setting, concentrating on not bumping something, rechecking and so-forth.

I seldom encounter a need to change a camera's setting once I enter a photo-shoot.  Sometimes I will change the over/under exposure settings, but that's easily done on the wheel control on the back of the camera.

In any event, I try to anticipate the conditions I will find myself in, set a camera's controls and functions, and then try to avoid, as I said, bumping any of the dials and controls during a shoot.

Reading the manual I came across the method Sony provides for disabling the dual wheel system.  It involves holding down the (unmarked) "function" key that sits just next to the shutter release button.  Now that this has been sorted I feel the camera won't "fight" me when I accidentally bump something or other.

According to DxOMark the Sony NEX-7 has 13.4EVs of dynamic range.  Which is to say, it has over 13 "f-stops" of dynamic range.  By comparison, the Sony A6000 I have is reported to have 13.7EVs of dynamic range.  The difference between these two cameras would be, I imagine, rather difficult to see in practice.

In summary, think the camera will be every bit as good an image making machine as the A6000 which I will continue to very much enjoy using.

Camera Story ~ Sony NEX-7

For the illustration images seen here I mounted-up a nice, light, sharp little Sigma 30mm f/2.8 EX DN.  Shortly after taking the images I blacked out the bright spots and replaced the Sigma lens with a Lens Turbo II, Nikon Nikkor-O 35mm f/2 pre-Ai setup.  It's in this configuration that I will see how things work out for me and my friend's "old" camera.

Sunday, November 17, 2019

Nikon Nikkor 50mm f/2 H pre-Ai, Micro-Nikkor 55mm f/3.5 pre-Ai ~ Macro Comparison

Something in an article on Nikon's Thousand and One Nights site caught my attention.  They said, referring to the Nikon Nikkor 50mm f/2 H -

"...We should also mention that the drop in performance for close-up work is small, and not only is the high quality maintained at the closest focusing distance of 0.45m (1.5ft.), but the lens also produces high quality when used on a bellows or extension rings for macrophotography..."

I happen to have a copy of the pre-Ai 50mm f/2 as well as a Micro-Nikkor 55mm f/3.5 which is also pre-Ai.  So I thought it might be interesting to see how the two lenses compared.

Setup ~
  • Sony A6000, 2 second delay, 100ISO
  • Big Beefy Manfrotto tripod
  • Straight-through Nikon to Sony E adapter
  • Lenses -
    • Nikon Nikkor-H 50mm f/2 pre-Ai
    • Nikon Micro-Nikkor 55mm f/3.5 pre-Ai
  • Two tourist "0 Euro" as flat subject-matter
  • Rawtherapee (no sharpening) to convert from AWR to jpg

Comparison ~

Here is the scene setup.

Scene Setup ~ Macro Study


Here is the comparison.

[If you click on the image it'll take you to the Flickr hosting site. Once there, look at the file at full resolution. In many cases the differences between lenses is small and likely can't be seen until you take a squint at the comparison at 100 percent.]

Macro Comparison ~ Nikon 50mm f/2, 55mm f/3.5


Comments ~

Note: Keep in mind that when dealing with macro subjects that the slightest field curvature in a lens will cause the edges of the frame to not be in focus.  However, if you either focus at the edges (which isn't exactly useful for keeping the center of the frame sharp) or stop the lens down to (as in this case, f/8) you will often see that the edges are, in fact, quite sharp.

Wide open the 50mm Nikkor-H f/2 pre-Ai is slightly soft in the center of the frame and very soft at the extreme edges.  Starting at f/2.8 the center is actually acceptably sharp.  This continues all the way through f/8 (and likely beyond, but I didn't test for the smallest apertures).  The edges of the frame become progressively sharp as the lens is stopped down.  Around f/8 the resolution begins to approach that of the Micro-Nikkor.

The Micro-Nikkor 55mm f/3.5 pre-Ai, by comparison, is very sharp from wide open across the entire field.  To me this remains an absolutely brilliant general purpose optic.

What I take from this comparison is that, yes, the Nikkor-H 50mm f/2 is mostly stable when focused at macro distances.  Like most non-macro lenses, it suffers from field curvature.  This makes the lens an interesting challenge when working with flat documents.  Yet when dealing with bugs, morning dew-drops and other potentially interesting subjects in a non-flat real world the lens is, as advertised, quite good for macro work.

Note 2: I have enjoyed reading Nikon's Thousand and One Nights series.  Their comments on early lens design, the trade-offs they made, and results they were seeking are, for me, very informative.  Their writings have helped me consider lenses more deeply than just the shallow one-dimensional considerations of "sharpness" and "resolution" that I've been overly prone to for the past 20 years.

Monday, November 11, 2019

Lens Stories ~ Nikon Nikkor-O f/2 pre-Ai

In a fit of downsizing the Lens Closet I sold a very good condition Nikon Nikkor 35mm f/2 Ai. 

There was just "something" on the edge of perception that made images special when I used this lens.  As always, for me regret is a powerful motivator.  Even though I am rich in 28mm and 50mm lenses, I just had to have another copy of the 35mm f/2.


Nikon Nikkor-O 35mm f/2 ~ Lens Stories

I've been thinking about this for over two years.  I've been trolling "that auction site" to see what might turn up.  I've been hoping that I could mend the errors of my ways.

Then, one day not too long ago, I came across a beautiful-looking early single-coated pre-Ai Nikkor-O version of the lens.  It had a case and, well, it looked rather un-used.

With patience that comes with age I bid late in the auction and, surprise!, won.

The package the lens arrived in had been sliced by a sharp blade along one seam.  While unopened, I wondered who did that and why?  The story I got from the point relais where I picked the lens up from was completely bogus.  Something was up.  So I opened the package right there in front of the man, just to make sure everything was OK.  It was, so I took my new acquisition and left.

From my first example of the lens I knew that Nikkor-O would be sharp.  There is a bit of field curvature, but along that line of that curvature images are sharp all the way to the edge of the frame.

Once back to home and hearth I took a quick look at the lens' out of focus rendition.  It looks and "feels" similarly to the Nikon Nikkor 50mm f/1.8 AiS and the 24mm f/2.8 Ai.  Which is to say, behind the point of focus the Nikkor-O is gently under-corrected for spherical aberration.

The all up cost, including delivery?  It came in under my self-imposed limit of 50Euro with more than a few Euro left over. 

When will I ever learn my lesson about selling lenses that I like?  For the moment balance in life has been re-achieved. 


Nikon Nikkor-O 35mm f/2 ~ Lens Stories

[NOTE: The photos in this album and this album, too, were shot using the Nikon Nikkor-O 35mm f/2 pre-Ai]

Saturday, November 09, 2019

Lens Stories ~ Nikon Nikkor 28mm f/3.5 pre-Ai, f/2.8 Ai

Returning to my usual and customary target of spending less than 50Euro a lens we come to a pair of 28mm Nikon Nikkors.  One is pre-Ai and f/3.5.  The other is Ai and f/2.8.


Nikon Nikkor 28mm f/2.8 and f/3.5 ~ Lens Stories

The Nikon Nikkor 28mm f/3.5 pre-Ai was, in fact, the lens that taught me the virtue of patience and keeping a sharp eye out for more fun toys.  Er.  I mean photographic tools.

Searching "that auction site" one day, I stumbled across an early design 28mm.  The bids were low and so I decided to watch it.  Then, at the last moment I bid low and still won.  The lens was scored for significantly less than 50Euro.

What I'd read was this was the first wide angle lens Nikon designed for the F mount SLR cameras.  Historically the first lenses hit the market in 1959.

Being an early design, "conventional wisdom" suggests this lens isn't as sharp as a more modern optic.  Maybe I have a "good" lens, but I don't see the f/3.5 lens' performance as being any less than outstanding from wide open.  Well, in the center, at least.  The edges aren't at all bad wide open when you take into account field curvature.  In general it takes stopping down to f/5.6 for things to clean up pin sharp across a flat field.

The Nikon Nikkor 28mm f/2.8 is a favorite of some people on the 'net.  It has a reputation for being sharp, light, and "handy".  This version of the optic was first introduced in 1974.  Looking at a cross-section of the lens it's easy to see where the f/2.8 design differs from the earlier f/3.5.

Taking into account for mild field curvature, indeed, my copy of the f/2.8 is sharp from wide open in the center all the way to the edges of the field.  And looking at the out of focus rendition, the more modern lens is ever so slightly under corrected for spherical aberration behind the point of focus.

While I think the f/2.8 gives a softer, more "delicate" out of focus rendition than the f/3.5, there are times when I feel the older design lens is just plain perfect as is.  Check out this example and perhaps you will see what I mean.

As for what I paid for the Nikon Nikkor 28mm f/2.8 Ai, there's a bit of a story.  It begins with a box of lenses that I bought of "that auction site."  A good 70 percent of the lenses were easily fixed up and one was, in fact, mint.  So I put it on a local to France sales site and suggested I'd be open to trades for something interesting.  One morning in my inbox was an email suggesting the 28mm.  The gent was happy for the trade and I'm sure the lens he now has is keeping him plenty happy.

In the end, the 28mm f/2.8 set me back all of 7Euro.

What I have here are two wonderful lenses.  They are simply Nikon pin sharp and both give a creamy out of focus rendition.  I can't tell the difference between them.

Do I honestly "need" two 28mm lenses, or three, really, if you count the pretty 28mm f/3.5 PC that I also own?  I suddenly find myself rather rich in this focal length.


Nikon Nikkor 28mm f/2.8 and f/3.5 ~ Lens Stories

[NOTE: The wide angle photos in this album were all shot using the Nikon Nikkor 28mm f/3.5 pre-Ai]

Thursday, November 07, 2019

Lens Stories ~ Nikon Micro-Nikkor 105mm f/4 Ai

Lens Stories ~ Nikon Micro-Nikkor 105mm f/4

On the same day, at the same time, and with the same seller that I broke my self-imposed Lens Budget Cap of 50Euros when I purchased the Nikon Nikkor 85mm f/2 Ai, I purchased a second lens.

The other lens was the worst condition lens that I think I've bought in nearly 30 years.  The first bad condition optic purchased lo those many years ago was a Zeiss Tessar 15cm that had come with a 4x5 view camera and who's front element was severely scratched.  The lens was so badly damaged there was no contrast in an image.  To help myself "feel" better about that transaction I rationalized by saying I received a pretty nice camera for little money and a junk lens for free.

In the case of the Micro-Nikkor 105mm f/4 Ai my rationalization for the purchase was a bit different.  Indeed, the exterior of the lens looks terrible.  Even that old 15cm Tessar looked better on the outside than this thing does.  There is so much "brassing" ("aluminuming"?) on the Micro-Nikkor that I might be able to use it as a reflector to bounce light into shadows.  I exaggerate, but not by much.

What separated my money from the wallet was something that I'd considered when looking at the out of focus rendition of the Micro-Nikkor 55mm f/3.5 pre-Ai and f/2.8 Ai lenses.  These lenses were my first encounter with nearly neutral spherical aberration control behind (and, of course in this case, in front) of the point of focus.  Hoping that Nikon had designed all it's Micro-Nikkor lenses this way led me to think the 105mm f/4 could be a natural compliment to the shorter focal length macro lenses.

I should stop here for a moment and explain why neutrally controlled spherical aberration in the out of focus areas is important to me.  CarsMotorcycles.

While for some subject matter I absolutely love the under-corrected spherical aberration out of focus rendition of both the 105mm f/2.5 and 85mm f/1.8 K, when photographing machinery I feel distracted by the "softness" and highlight "pop" I many times get when using those lenses.  They "feel" like outstanding portrait lenses more than they feel like the best tools to document machines.

After getting the Bruised Beast home I took a look at its "resolution" and its out of focus rendition.  Yes, the Micro- Nikkor is as sharp as I expected it to be.  Yes, the Micro-Nikkor has a flatter field from wide open than my other 105mm lenses.  But...  Surprise!  Surprise!!  The out of focus rendition is closer to the performance of the 105mm f/2.5 P and updated design Ai lenses than to the neutral spherical aberration corrections of the Micro-Nikkor 55mm lenses.

So... now what to do...?


Lens Stories ~ Nikon Micro-Nikkor 105mm f/4

Tuesday, November 05, 2019

Lens Stories ~ Nikon Nikkor 85mm f/2 Ai

OK.  So I broke my own self imposed budget limit.  I couldn't help myself.  I'm sure I could justify the purchase based on non-budgetary criteria.  My fuzzy little mind remembers wondering how Nikon's successor to the 85mm f/1.8 H, HC, K lens performed behind the point of focus.

I'd read that the 85mm Nikkor f/2 was a "boring" lens.  Sharp(ish) wide open and nothing special by way of its out of focus rendering.

I owned a pretty Nikon Nikkor 85mm f/2 Ai when I first moved to Europe.  But it was sold in a fit of "downsizing" the photographic tools cabinet.  Slowly, over the years, I came to regret the decision.  So when this lens came up at a somewhat reasonable price, my 50Euro per-lens budget cap went out the window.

Nikon Nikkor 85mm f/2 ~ Lens Stories

Being one to not trust what's posted on the 'net, I decided to have yet another look at this lens.  Here is what I found (confirmed, yet some more?, oh gawds, the Insanity continues).

The Nikon Nikkor 85mm f/2 Ai is very slightly sharper wide open than any of the Nikon Nikkor 85mm f/1.8 H, HC, or K lenses that I've owned.  By f/2.8 my eyes can't see any difference in "resolution" between the two lenses.

Looking at behind the point of focus rendition I see that the f/2 lens is much more neutral in it's correction of spherical aberration than the f/1.8 lens is.  Perhaps it is this characteristic that some people find "boring?"  I wonder.

In any event, the f/2 lens has shallower depth of field wide open than it's f/1.8 sibling.  This has a lot to do with how the out of focus region spherical aberration is treated.

Nikon Nikkor 85mm f/2 ~ Lens Stories

Standing back a bit and looking at the two lens designs, I can hazard a guess or two about their performance trade-offs and design details.  Perhaps the most obvious is this.  The f/1.8 H, HC, K lens is a wonderful portrait lens in the old style.  The lens designer gave that lens a subtle, beautiful behind the point of focus rendition.  Highlights positively "glow" and it reminds me in some ways of a lovely Wollensak Verito large format optic.  The complement to the older 85mm lens, in my mind, is the lovely 50mm f/1.8 Ai/AiS.

The Nikon Nikkor f/2 Ai lens, on the other hand, feels well corrected.  It could be a good companion to the Micro-Nikkor 55mm f/3.5 pre-Ai and f/2.8 Ai and Nikkor-O 35mm f/2 lenses that I tend to shoot with.

Sunday, November 03, 2019

Lens Stories ~ 3 Nikon telephoto zooms

I'm at a loss to explain why the prices have seemingly dropped out of the old manual focus lens market.  Sure, there are likely more than a few good reasons for this, but nothing stands out in my mind as the _most_ likely explanation.

No matter.  I find I'm enjoying finding brilliant optics for not much money.  It's too much fun, in fact, and I've made something of a game of it all, searching for the cheapest and best optics I can find.

I set an arbitrary upper limit on what I will spend on an old piece of glass at 50Euro.  Perhaps surprisingly I'm able to many times pick up a lens for less than that, delivered.  Here are three examples.

3 Nikon zooms ~ Lens Stories

Some time back I picked up a Nikon Nikkor 80-200mm f/4.5 N for what I felt at the time was a shockingly low price (much less than the one seen in the previous link).  The lens is in very good condition and the optics are mint.

Not long after I found a mint condition Nikon 75-150mm f/3.5 AiS for half what I paid for the 80-200mm.  These days no one seems to like the short 2x zoom, but go back to when the lens first came to market and you'd see fashion photographers use practically nothing else (yes, I exaggerate, but not by much).  This lens, while costing so little, delivers much more than you might believe possible.

After spending the winter in Nice I came home and causally scanned the latest lens offerings on the 'net and came across the mighty Nikon Nikkor 100-300mm f/5.6 AiS for what I'd paid for the 80-200mm.  This model zoom is long but makes not accommodation for a tripod foot to help balance the rig while on a tripod or monopod.  But, it's a lot lighter than other lenses in this class, so I thought I'd give it a try.

The 100-300mm was being sold "as is."  This is usually an indication that something is wrong.  In this case the focusing sleeve was reportedly "loose."  This happens frequently with these old zoom lenses.  Nikon used a felt ring to keep the push-pull focusing sleeve snug against the inner barrels.  When the lens arrived it turned out to be much much better than expected.  It's perfectly usable "as is."

Normally I prefer fixed focal length lenses.  Traditionally they tend to be sharper across the field and are better able to manage spherical aberrations in the out of focus areas.  So I put these three zooms to "the test" to see what Nikon did with their early versions.

In all three cases, resolution in the center of the field of these zooms are at least the equal to their fixed focal length counterparts.  The edges of the 75-150mm and 80-200mm were testing slightly soft.  The 100-300mm, however, is brilliant straight across the frame.

3 Nikon zooms ~ Lens Stories


Then I reminded myself (by conducting yet more comparisons) that many of my fixed focal length lenses suffered from field curvature.  When I accounted for this be refocusing at the edge of the frame when I conducted my "resolution" comparisons I found that in nearly every single case that the "resolution" at the edge matched the "resolution" at the center _from wide open_.  So I took another look at the two shorter zooms and, yes, found they too can suffer from field curvature and produce sharp images at the edge of a frame when the curvature is accounted for.

Next, I took a look at the  out of focus rendition behind the point of focus of these zooms.  True to what Nikon says about nearly all their lens designs, the 75-150mm and 80-200mm lenses at the shorter focal lengths have been under-corrected for spherical aberration behind the point of focus.

One more thing of interest, however, came quickly apparent.  In the case of these two zooms, there was something happily surprising that happens at the longest focal lengths, and in the case of the 100-300mm, the same thing holds true at all focal lengths. The out of focus rendition is dreamy creamy smooth neutral.  The rendition is so good that they are every bit as good as any of the current new all the rage "smooth trans focus" apodization filter lenses from Sony (formerly Minolta), Fuji, and Canon.  Yes.  It's true.

3 Nikon zooms ~ Lens Stories


So what do I have here?  In total, here are three wonderful Nikon zoom lenses. The zooms are sharp sharp sharp in a fixed focal length sense of "sharp".  Yes, they gently suffer from varying degrees of field curvature, though none are worse in this regard than the fixed lenses I have looked at.  Best of all, they all have beautifully controlled out of focus rendition.  The only difference from their fixed focal length siblings, really, other than the obvious ability to change focal lengths, is the maximum aperture.

If I had to choose just one lens (and thankfully I don't, certainly not at these kinds of prices) the 100-300mm f/5.6 AiS stands out as something truly special.

Tuesday, October 01, 2019

Spherical Aberration and Depth of Field ~ a comparison

Looking at the effects of spherical aberration on out of focus rendition has led me to better understand depth of field and why calculating it is not as straightforward as one might believe.

A neutrally corrected lens (such as a Nikon Micro-Nikkor 55mm f/3.5 or f/2.8, or a Nikon Nikkor 85mm f/2) will show a balanced out of focus transition.  That is, the rate of change from sharp to out of focus will be similar both in front of and behind the point of focus.

A lens (such as a Nikon Nikkor 85mm f/1.8 K or 105mm f/2.5 P) that is under-corrected for spherical aberration behind the point of focus will show greater depth of field behind the point of focus than in front of that point.

Conversely, a lens (such as a Nikon Nikkor 50mm f/2 H) that is over-corrected behind the point of focus will show a shallower depth of field behind the point of focus than in front of that point.

Studying the links found under Resources (below) helped me understand how this is possible and how optical physics and photographic imaging work in real life.

I happen to have three lenses that span the range of neutral correction to severely under-corrected spherical aberration.  I didn't feel any need to compare an over-corrected lens as the effect should be obvious from looking at the Comparison image below.


Setup -
  • Sony A6000 handheld
  • Lenses using with a Lens Turbo II focal reducer -
    • Nikon Nikkor 85mm f/2 Ai 
    • Nikon Nikkor-K 85mm f/1.8 K pre-Ai
    • Pentax 85mm f/2.2 Soft (in Nikon F mount - the only one I've ever seen)
  • NOTE1: Lenses were shot at their widest apertures only
  • RawTherapee to convert RAW files into jpg using "Film low ISO" profiles

 Comparison -

The image on the left shows the effect of spherical aberration on depth of field.  The image on the right is simply the scene as it came out of the camera for each lens compared.

If you click on the following image you can inspect it at 100 percent.

Out of Focus Comparison ~ 85mm lenses


Comments -

NOTE: I feel the Lens Turbo II focal reducer adds a bit of under-corrected spherical aberration.

NOTE 2: Recall that if a lens is under-corrected behind the point of focus that the very same lens will be over-corrected in front of that focus point.

The neutrally corrected Nikon Nikkor 85mm f/2 Ai lens was focused on the red 80cm indication on the tape.  The 79cm (behind the point of focus) and the 81cm (in front of the point of focus) are to my eyes at the limit of what I would call "in focus" - 1cm in front and 1cm behind the point of focus means that in this situation there is a total 2cm of "depth of field".

The under-corrected Nikon Nikkor 85mm f/1.8 K pre-Ai lens was focused on the 79.5cm mark (I missed the 80cm mark).  Using the f/2 lens as a reference I would say that the 80cm mark in front of the point of focus and the 77.5cm mark behind the point of focus are at the limits of what I would call "in focus." 

This is approximately 0.5cm in front and 2cm behind the point of focus - with a total "depth of field" of 2.5cm.  Clearly, "depth of field" has contracted in front of the point of focus and expanded behind the point of focus.  This, directly, is the effect of behind the point of focus under-corrected spherical aberration on "depth of field".

The severely under-corrected Pentax 85mm f/2.2 Soft lens is an interesting study in "depth of field."  It is so severely under-corrected and so filled with spherical aberration that I missed the intended 80cm focus point.  Everything from 84cm through to 75cm appears to my eyes to be well defined sharp to be called "sharp."  In this setup the Pentax Soft is giving 9cm of "depth of field."


Resources -

For further information on how the topic of out of focus rendition, optical properties, and Nikon lens design history, please refer to the following -

A PhD thesis on the impact of "soft focus" lenses on the history of photography - http://research-repository.st-andrews.ac.uk/handle/10023/505

An excellent starting point for understanding out of focus rendition (I might not completely agree with his interpretations/observations, but his foundation of understanding is quite good) - http://jtra.cz/stuff/essays/bokeh/

Nikon lens design histories - https://imaging.nikon.com/history/story/

Point light source discussions - https://www.dpreview.com/forums/thread/4031515

Zeiss comments on optical design -  https://lenspire.zeiss.com/photo/en/article/how-does-zeiss-define-bokeh-an-interview-with-dr-stefan-ballmann

Metabones Focal Reducer whitepaper - https://www.metabones.com/assets/a/stories/Speed%20Booster%20White%20Paper.pdf

Wednesday, September 25, 2019

Out of Focus Rendition ~ Yet More Comparisons


Looking at a WiFi bridge we have in the apartment I could see the potential for looking at bit more at out of focus rendition in old Nikon Nikkor lenses.  I could get out of focus dots and lines with no more effort than clicking the shutter.

Setup -
  • Sony A6000 handheld
  • Lenses using with a Lens Turbo II focal reducer -
    • Nikon Nikkor-H 28mm f/3.5 pre-Ai
    • Nikon Nikkor 28mm f/2.8 Ai
    • Nikon Nikkor-O 35mm f/2  pre-Ai
    • Nikon Nikkor 50mm f/1.8 AiS
    • Nikon Nikkor-H 50mm f/2 pre-Ai 
    • Nikon Micro-Nikkor 55mm f/3.5 pre-Ai
    • Nikon Nikkor-K 85mm f/1.8 K pre-Ai
    • Nikon Nikkor 85mm f/2 Ai
    • Nikon Nikkor-P 105mm f/2.5 pre-Ai 
    • Nikon Micro-Nikkor 105mm f/4 Ai
  • NOTE1: Lenses were shot at their widest apertures only
  • NOTE2: Out of focus samples are from points _behind_ the point of focus to compare background out of focus rendition
  • RawTherapee to convert RAW files into black and white and to set the black levels
  Comparison -

Here is the comparison setup.  Pretty WiFi bridge, don't you think?  More seriously, the top leading edge of the bridge is where I focused.  As you can see, the body of the bridge goes out of focus.

Out of Focus Rendition Comparison


If you click on the following image you can inspect it at 100 percent.

Out of Focus Rendition Comparison


Comments -

NOTE: I feel the Lens Turbo II focal reducer adds a bit of under-corrected spherical aberration.

If there is a doughnut highlight outline around the edge of an out of focus dot or a stronger line along the edges of an out of focus line, the lens likely has over-corrected spherical aberrations behind the point of focus.  Some people call this "soap bubble bokeh."

In this comparison I feel the following lenses exhibit noticeable over-corrected spherical aberrations behind the point of focus.
  • Nikon Nikkor-H 28mm f/3.5 pre-Ai
  • Nikon Nikkor-H 50mm f/2 pre-Ai

If a dot or line is smooth across the out of focus area, then the lens exhibits neutral spherical aberration correction.  

In this comparison I feel the following lenses exhibit neutrally controlled spherical aberrations behind (and, of course, in front of) the point of focus.
  • Nikon Micro-Nikkor-P 55mm f/3.5 pre-Ai
  • Nikon Nikkor 85mm f/2 Ai

If a dot or line is brighter in the center of the out of focus area, then the lens exhibits under-corrected spherical aberrations.  Nikon in their Thousand and One Nights series describes this as leading to a "delicate" out of focus rendition.

In this comparison I feel the following lenses exhibit noticeable under-corrected spherical aberrations behind the point of focus.
  • Nikon Nikkor-H 28mm f/2.8 Ai
  • Nikon Nikkor-O 35mm f/2 pre-Ai
  • Nikon Nikkor 50mm f/1.8 AiS
  • Nikon Nikkor-K 85mm f/1.8 pre-Ai 
  • Nikon Nikkor-P 105mm f/2.5 pre-Ai
  • Nikon Micro-Nikkor 105mm f/4 Ai

Using this knowledge I can now match the "look" of images that I make.  That is, if I want the Nikon described "delicate" out of focus rendition, I know which lenses to choose from.  Similarly, since I don't like the "harshness" of over-corrected out of focus rendition, I know which lenses to avoid.


One last thing.  I feel I should comment on the use of black and white for these comparisons.

Many of the lenses I looked at were designed during the era of black and white film.  When looking at the color rendition, some of the lenses showed a bit of what I must interpret to be chromatic aberration.  That is to say, the edge of out of focus areas are tinted/tinged with magenta on one side and green on the other.  When shooting black and white film, this wasn't easily observable.  But with the advent of color film, lens designers now had the opportunity to correct more lens faults in response to user demand for "better" lenses.

Here is an example of what I mean (with increased saturation and contrast to more strongly illustrate the effect).


Out of Focus Rendition Comparison



Resources -

For further information on how the topic of out of focus rendition, optical properties, and Nikon lens design history, please refer to the following -

A PhD thesis on the impact of "soft focus" lenses on the history of photography - http://research-repository.st-andrews.ac.uk/handle/10023/505

An excellent starting point for understanding out of focus rendition (I might not completely agree with his interpretations/observations, but his foundation of understanding is quite good) - http://jtra.cz/stuff/essays/bokeh/

Nikon lens design histories - https://imaging.nikon.com/history/story/

Point light source discussions - https://www.dpreview.com/forums/thread/4031515

Zeiss comments on optical design -  https://lenspire.zeiss.com/photo/en/article/how-does-zeiss-define-bokeh-an-interview-with-dr-stefan-ballmann

Metabones Focal Reducer whitepaper - https://www.metabones.com/assets/a/stories/Speed%20Booster%20White%20Paper.pdf

Tuesday, August 27, 2019

Pictorial Photography ~ three yearbooks

Back in the day, a certain Clarence H. White was a leading light in the area of photography as art.  His influence can't be understated.

Yet within the photographic culture we remember little to nothing about him.  Stieglitz?  Yes.  Weston?  Yes.  Other practioners?  Not so much.

I have the strange sensation that since "pictorial" photography was practically outlawed by Edward Steichen after seeing the light (pun intended), many photographers and their work have been largely forgotten.

So it was something of a surprise to see on the Gutenberg Press that they have three year books edited by White that are available for free download.

If you are interested in pictorialism in photography, or soft focus lenses, or late-19c tools, materials, and techniques, or photographic history these might be worth a look.

Paris Doux

Tuesday, July 16, 2019

Paris Exhibition ~ Sally Mann until 22 September 2019

Sally Mann has a beautiful show running at the Jeu de Paume in Paris just now.

My wife and I went last Sunday to see it just after the Bastille Day celebrations were finished (the museum didn't open until 13h30 that day).

The crowds were small-ish, though it was difficult to move freely through the first couple of rooms of the exhibit.  But once well inside the show there were fewer people and we could enjoy taking our time to look at the photographs.

My gawd! those photos can be beautiful.  It was a real joy to see deep, richly printed black and white images.  We found Sally Mann's work to be very expressive and deeply moving.

In general, I think the French have a difficult time understanding and appreciating the large landscape works of someone like Ansel Adams.  Those works tend to be remote and cold and people aren't real sure how these can be appreciated.

Certain West Coast photographers like Edward Weston are more approachable for the French.  And if I understand correctly, it has to do with his bohemian lifestyle (he reportedly had many lovers), his images of people and more personal subjects and his political sensibilities (he spent time in Mexico around the edges of the Communist movement).

From the number of shows we see listed here in Paris, the French embrace American street photographers, mainly from New York.  And they really appreciate good American photographers who make Paris their home, like Peter Turnley.

So it was interesting to us to see how the French reacted to Sally Mann.  Her work is not as literal as some people might be used to.  Listening to the French as they talked through the show was fascinating.  Some marveled at the optical effects that create smooth out of focus background renditions.  Some people were taken by the beauty of Sally's subjects (and my gawd! can her subjects be beautiful).  And others were surprised by how slavery in America continues to impact culture and society there and how this history could be so accurately portrayed in an artistic work.

For me the exhibit worked well on two levels.  The first is that her work is inspirational.  Sally Mann has found a way to use the tools of photography to express the various themes she explores in a way that transcends the tools in the creation of her works of art.

The second level is more profound.  Much is made about race relations in America.  After seeing the show I can't help but feel a deep sadness for terrible things in American history that continue to influence the present.