I got looking around this blog and my old Hevanet site and realized, there's a ton of stuff scattered here and there. The exercise sent me down Memory Lane and helped me wonder what have I done? Why? Did I accomplish anything? Something? A lot?
So I set about choosing topics that seemed most important to me and organized them into this, a short list of "stuff" that I've poked at, pondered, considered, tested, and wrote about.
In links and a with little commentary...
Large and Medium film format lens testing ~
The original Hevanet site -
From this site (essentially copies of the above, but with additional posts as I started to transition to digital) -
It set a foundation for my understanding commercially available optics for photography. Yes, there are gaping holes in the overall subject of "lens testing" - such as aberrations of various sorts, contrast transfer (MTF), field distortion, and field curvature. Alas, I wanted to start somewhere and this was it.
It turns out, it's really difficult to find a "bad" lens and at optimal working apertures it's nearly impossible to tell the difference between them. In fact, in the vast majority of cases I've examined over the decades of fooling with this stuff, I've found the light gathering materials (film, sensor) to be the limiting factor to resolution.
Out of Focus Rendition ~
- Summary of Understandings
- Example of Sigma lenses - check the right side bar for a laundry list of other lenses considered
I went down this path after reading a whitepaper Zeiss published on the topic. Looking at lenses I own I learned that zoom lenses can have very smooth behind the point of focus. Old Nikkors seem to have a "condom ring" around an under-corrected for spherical aberration out of focus disk. Modern fixed focus lenses seem to tame the "condom ring" fairly well.
I confirmed for myself that overcorrected for spherical aberration lenses behind the point of focus give soap bubble specular highlights, particularly when corrected for maximum resolution in the center of the field wide open. Many Cooke triplet, a few tessar formula lenses and most Canon FL and FD 50mm lenses exhibit this. The cheap Nikon 75-150mm f/3.5 Series E is an opposite example. It's very smooth behind the point of focus and is a touch soft wide open.
Digital Zone System ~
- Built a step-wedge to understand B&W tones in the digital realm
- RAW - Test to see how sensors behave
- In-camera JPG - Test to see how Sony ASIC's process images
I learned a tremendous amount in adapting digital to the old Adams/White Zone System.
With film we exposed for the shadows and processed for the highlights. In digital we have the opportunity to do the exact opposite - expose for the highlights and process for the shadows.
Another important finding is that for current generation of digital CMOS sensors +4EV is pure white - there seems no way around this - it's simply a hard fact - for now, at least. This needs to be kept firmly in mind when processing digital to look like film until new sensor tech is released that expands the upper end of the tonal range (think photon-counters).
On the other hand, digital sensors are very good in the shadows - often down to -6EV or -7EV (perhaps deeper, depending on end viewing conditions - book or LCD) - well beyond what film was ever capable of. Using this knowledge I find if I want digital whites to look a lot like film with an extended exposure shoulder, I can under-expose by -1EV, then raise the -1EV tonal value to Zone 5/0EV/118dec.
Soft Focus on Miniature Formats ~
- Then vs Now - Soft Focus tools and understanding imaging potentials
- Cosina 55m f/2.8 matrix of softness - an example (other lenses are also considered in adjacent posts)
The goal was to see if there was a way to mimic old large format soft focus work in miniature formats (full frame, APS-C) after finding specialty soft focus lenses to be far too strong for my liking - I traded a pretty to look at but impossible to use Pentax 85mm f/2.2 Soft Focus for something more useful to me.
A key arrived in the form of an email from Russell Young, PhD - who's thesis is on Pictorial photography. A link to a 1906 book in French proved most useful and I was able to quickly/easily adapt old calculations to understanding what might be possible in current time.
There are two aspects I found helpful. First, front element focusing lenses often introduce optical imperfections much in the manner of old large format softies. The early Wollensak Velostigmat Series II was the large format inspiration. First element focusing lenses do exist, typically for old SLR 35mm systems - but hunting and gathering them can be a challenge.
Second, a good understanding and careful use of soft focus filtration can be eminently useful in miniature formats. There are many reasons why filters are implemented the way they are, and each delivers its own character and rendition style.
Final Comment ~
After finding very few resources (in literature, magazines, or on the internet) I realized I had to work things out for myself.
Anyone can do what I've done in any and all of these subject areas and probably can improve on these works. It's all very simple and straight forward. And yet, outside of photography club journals from the late 1800's/early 1900's and a series of lens resolution tests run by Modern Photography during the 1970's I've found nothing comparable.
Developing as deep an understanding as I could while keeping things as simple as possible for reproducibility and clarity, along with articulating interpretations as accurately as possible, has been my goal. Applying what I've learned over the years to my photography is increasingly gratifying.
Testing for learning/understanding/knowledge without tangible results would, after all, be rather pointless, wouldn't it?
