Tuesday, April 15, 2025

Chromatic Aberrations ~ new vs old lenses

I'm not sure how it came to me, but I had a question of how chromatic aberrations might effect the appearance of "sharpness" in an image and took five lenses of relatively different vintages to have a look.

Software automation can correct for various optical "defects", including field distortion, chromatic aberrations (CA), and "sharpness."  As a first step for my comparison I would need to turn all of that off to note what just the lens was doing.

You see, I had the sneaking suspicion that modern lenses were being tweaked into fabulous goodness by lens correction profile, or .lcp, files that are often hidden from a user during RAW image processing, but I wasn't sure.  I'd heard over the years many marketing claims as to new lens design technologies improving all manner of traditional optical defects, so maybe the .lcp files weren't doing as much as I thought?

The lenses on hand included:

  • Nikon Nikkor 24mm f/2.8 Ai
  • Pentax-M 28mm f/2.8
  • Sigma 19mm f/2.8 EX DN E
  • Sigma 24mm f/3.5 i-Contemporary
  • Takumar 28mm f/3.5 SMC (second version)

Using a Sony A6300 set on a tripod, +1EV (because of the strong white back-light), 2 second self timer, ISO100, focusing on the stick, then processed in RawTherapee using only the demosaic and Camera Standard tone-curve enabled color management steps (to keep software processing to an absolute minimum).  

Voila! a mundane scene of my Rescue Orchid - 

Scene of CA investigations 

There were a few surprises awaiting me.  Looking for chromatic aberration, here's what I found  -

Comparing CA without processing intervention

Comments -

The Sigma 24mm f/3.5 shows the strongest chromatic aberrations of the five lenses I looked at whereas the old Pentax-M and older Takumar 28mm lenses show the best CA corrections.  Even the Nikkor 25mm appears to show less CA than the Sigma 24mm and is perhaps better at CA correction than the Sigma 19mm f/2.8 APS-C.

Looking at how CA effects the sense of "sharpness" I see that, yes, indeed, images look less "sharp" when CA is stronger.  Makes me wonder how much modern lenses rely on software intervention to make them look as good as they do?


Sunday, January 05, 2025

Countering the rising costs of photography ~ On Being A BottomFeeder

Thom Hogan has written an excellent article that observes and comments on the rising costs of photography and the sources of those costs.

Being the contrarian penny pincher that I am, I thought I'd give a few examples of how I no longer "play that game."  In fact, I've not "played that game" for decades.

When I had a job and could afford such things I would buy new pieces of camera equipment from time to time. The last new camera I bought was a Sony A6000, and that was well over ten years ago.  Though, thinking about it a moment, maybe the last new camera I bought was a Sony A5000.  The memory fades.

Most of my efforts however, even when I worked, were buying/using/selling used gear.  Hundreds and hundreds (more likely thousands) of lenses and cameras have passed through my hands over the years.  The habit carries forward into the present.

On the image processing side of things I leveraged my knowledge of and contacts with the Open Source community, and experiences of deploying large scale Linux systems.

So, my costs have been traditionally low.  I see no reason why someone truly interested in photography either as a hobby, artist, or working professional can't do something similar.

Musee d'Orsay, Paris ~ 2024

Sony A7RII, Sony FE 35mm f/2.8 ZA
RawTherapee, Digital Zone System
Pt/Pd tinted

Here are a few things I do.

Buy Used -

It seems like an obvious place to start. 

If I worried about reliability the thing I note is that most of my used cameras these days are very "low mileage."  One Sony A7 I bought had around 800 clicks on the shutter, looked well cared for, and set me back 450Euro five years ago.  Another had less than 2,000 clicks for a slightly lower price, again, five years ago.

On the other end of the spectrum, I recently picked up a Sony A7RII with 72,000 clicks for a nice low low price.  This, even though the camera remains in excellent condition and the shutter is rated for 500,000 clicks.

Similarly, used lenses can be attractively priced.  For less than the price of a new Sony A7III body (even on sale) I've been able to build an A7 kit with three fixed focal length lenses.  Two lenses are usually expensive Zeiss labeled and one is like new latest generation Sigma.  All are auto-focus, modern optics.

Thinking again about reliability, of all the used gear that's passed through my hands, there's not one single "bad deal" that I can recall. I take that back.  I bought a Fuji 240mm A f/9 large format lens many years ago that arrived with difficult to see sand-impacted front element.  It was returned for a full refund and the seller apologized.  He remembered he'd recently taken the lens to Death Valley where it had been windy.

Image Processing -

I tend not to spend too much on computers and stick to using a laptop.  Any decent quality device will do.  HP, Dell, and, hmmm... that's about it, actually.  For security reasons I assiduously avoid anything designed/manufactured/marketed by the Chinese.

Once an inexpensive computer is at hand, I wipe the disk and install a decent distribution of Linux.  That OS remains for me the most secure way of engaging the world.

On top of Linux I load the image processing applications I like.  These include RawTherapee, the Gimp, Luminance HDR, and Hugin.

I use RawTherapee for performing the "heavy lift" image processing.  When I need to "tweak" something or want work graphically I transition to the Gimp.  While I've not done a lot of HDR recently, I still low Luminance HDR, just in case.  When the bug hits and want to make my computer cry I use Hugin to stitch very large high resolution images.

Over the years I've paid close attention to differences between commercial and Open Source software capabilities.  What I've found is that Open Source software can be more complex and require more steps to accomplish common tasks.  Coming from commercial software where many potentially important details are hidden from users, Open Source software can be a little overwhelming at first.  

Part of the challenge is that there are so many options and tools and standards that is seems as if nothing is being left out.  However, and this is important to me, once I understood the tools and specifications implemented by those tools, I've come to realize there is nothing more flexible, more comprehensive, nor more accurate (in particular color management) than something like, say, RawTherapee for image processing. 

In fact, if I felt I couldn't live without Adobe "color science" or Fuji "film simulations" or Hasselblad "Natural Colors", all I'd have to do is load the .dcp and .icc files into RawTherapee and select the styles and looks I want during processing.

To back everything up, I buy new USB drives.  This is one thing I will not buy used.  New 5tb spin drives are shockingly inexpensive.  Solid State drives are becoming more affordable.  Everything, RAW files, processed images, documents, works in progress, everything, gets tossed onto a drive every so often.  And I'm tending to keep multiple backups, too, "just in case" something fails down stream.

That's just about it.  Very simple.  Very straight-forward.  Nothing fancy.  I don't pay rent on any software.  No Apple tax.  No Microsoft madness.  No Adobe rent until I die silliness.  I own my cameras and lenses outright and at as low a price as the market offers.  I don't get a boatload of noisy advertisements from the apps and OS I use.  My systems are secure, stable, extensible, and portable.

There you have it.  This is how I manage my photography eco-system costs while living on a fixed income.