Bill P

As always, this list can quickly degrade a subject into obscure arcane semi scientific mumbo-jumbo. This is not an optical science list. This is a photography list. Does the lens give you suitable results? then keep it. Do you find something troubling in the results? Then sell and replace it.

See how easy that was!

selmslie Loc: Fernandina Beach, FL, USA

Both tutorials agree with each other and they are both correct. Focal length is not a factor. You just don't understand why.

If you take the time to look at the diffraction limit calculator you will see that, without accounting for high megapixel resolutions, the diffraction limits are close to f/11 for full frame, f/8 for APS-C and f/5.6 for M43. It goes the other way for medium format where 6x6cm is not limited at f/32 and 4x5 film is OK at f/64.

TriX Loc: Raleigh, NC

I take your point, but am going to have to respectfully disagree. The references and formulas cited are certainly not “semi scientific mambo jumbo”, they are scientifically proven facts and equations defining how light is diffracted. A basic understanding of how light behaves is inherent in understanding the technical side of photography (without which, there is no photographic art). I personally find that it is much more useful to actually understand how the mechanism of something works than accumulating various facts and opinions, which may or may not answer specific questions about performance of a system. I do understand that others may not feel the same, but the number of posts in threads of this type demonstrate that there are many of us that do.

Bill P

But as I said, these discussions have only slight utility to a photographer. I doubt any of us imagine a career designing lenses.

AndI fully believe that some of the comments are scientifically valid and others are semi informed claptrap. Don't know how to tell wheat from chaff and don't care to. I've stated my lens testing regimen, and it works for me. It it doesn't work for you, I pity you.

selmslie Loc: Fernandina Beach, FL, USA

Maybe you should post some images so we can see how well it works for you.

Bill P

Same question same answer. I'll post images on the internet right after I make a bunch of prints and put on the sidewalks.

Linda From Maine Loc: Yakima, Washington

Bill, I suspected your "concern for Linda" was insincere, but thought I'd give you the benefit of the doubt. Unfortunately, I can't block you from commenting - Admin rescinded that option last year - so, if you feel you absolutely must trash this topic, carry on.

For all others, thanks again for your interest and courteous discussion. I'm outta here.

Bill P

Sorry, but my concern for you was in no way insincere. This is why the internet isn't really good for our society. Everyone interprets things in their own way. Sorry you saw it that way. But in no way do I think this overly hairsplitting discussion is worthwhile.

TriX Loc: Raleigh, NC

No need to pity me, I have a calibrated testing program (see charts I posted above) that yields very accurate measurements, not subjective judgements, so I know exactly where the diffraction trade offs are on every one of my lenses (and I also know the theory behind the results).

Bill P

As I have tried to state, other than self validation, what does this gain you in your photography? Isn't it enough to know that the photo looks good? Do you doubt your own eyes? I find life easier if I remove all needless crap from my plate. And I find pixel peeping to be needless crap. and understand I don't mean to demean you, I'm trying to suggest something that will make your life better. Your photos have always impressed me, so I don't see where this task will help you.

And I know, I know, there are those out there that need more structure in their life than I do.

cbtsam Loc: Monkton, MD

then stop following it

Bill P

Although your suggestion shows a lack of consideration and kindness, I am going to quit this stupid list as it isn't about photography, it's all about gear and needless details.

Blenheim Orange Loc: Michigan

Format, print size and viewing distance are all factors, as has been mentioned.

My guess is that if you printed images from a full frame DSLR at 24mm X 36mm you would hardly notice any diffraction.

E.L.. Shapiro Loc: Ottawa, Ontario Canada

I certainly agree that understanding the mechanics, physics (optics), and chemistry of how out photographic equipment functions is of significant value in one's photography endeavors. My career in photography started off in an apprenticeship where I learned the "trade" or art from a strictly applied workaday viewpoint. Later on in my life, I had the opportunity to go back to school, as it were, and study, in an academic environment, the more scientific aspects. Optics class was fascinating and they ever drill down deep into "glass"! The course covered every known permutation of lens aberrations, distortion potential and defect and how optical engineering, over the decades as addressed, corrected to some degree or even designed lenses that utilized theses aberrations to design special purposes lenses. All very interesting and to this day I can spot a bad case of "zonal spherical aberration" or "chromatic aberration", or "curvature of field" from a mile away- well a respectable viewing distance.

Halfway there to the degree program, I decided, much to the chagrin of my family, who wanted an engineer, not a photographer, I dropped the program, switched to Applied Photography and unlike my classmates did no stay in Rochester and go to work for Kodak or Bausch and Lomb, etc., and just went back to work!

My academic knowledge does occasionally help me in troubleshooting a technical issue but in my day to day work as a portrait and commercial photographer, much of the extremely "drilled down" phenomena do not come int play. There is absolutely no doubt that diffraction and may other of the aforementioned optical aberrations still exist in out modern lenses- some to a comparatively lesser degree than in the distant past but the practical emphasis for working photographers is how to select lenses accordingly for the work they are doing, how to recognize and deal with any negative optical phenomena and work around them.

I am not averse to long online debates and civil arguments about many of these technical matters. Oftentimes, however, I find there is a propensity on the part of some participants to argue against solid proven facts, get into too much etymology and word usage debates, and in frustration post borderline nasty comments about the content and length of a thread.

I have heard and read, right here on this forum, some folks describing how the walked away for a once-in-a-lifetime picture opportunity because the would have to stoop down too much and get diffraction. People sometimes become too preoccupied with some of this data and perhaps forego the fun and art of the craft. Sometimes I suspect that some photographers suffer from "optical hypochondria" that is they blame their poorly crated work on "diseases" the lenses do not have! have Another suggestion- perhaps we need, on this forum, yet another specialized section for "Photographic Science".

I agree about your remarks about the properties of LIGHT. My preoccupation with light isn't what it does once inside the lens or the camera but what it does when, how and where it strikes the subject. It is surprising how many photographers use terminology like "angle of incidence and the inverse square law", and don't really know how these theories impact the aesthetics of their images. There are so many interesting phenomena and like unseen secondary light, trans-illumination, the dynamics of feathering and much more.

This is not confined to photography, I know a few audiophiles who can't enjoy their multi-thousand dollar system because it won't reproduce frequencies that can only be detected on an oscilloscope or if you happen to be a cat. GAS? sound familiar?

burkphoto Loc: High Point, NC

At the photography company I worked for, we had a team of photographers who, prior to 2006, used 8x10 view cameras with 300mm lenses to photograph graduating classes, bands, fraternities, etc. We made 30x10 inch panoramas from the center of those negatives. Those photographers used f/32-f/45, and occasionally f/64.

When we killed film and gave them Canon 5D II cameras, they stopped the lenses (Tamron 28-75mm f/2.8 zooms) down to f/32 by habit, creating many extremely soft images, due to diffraction. They had to try them at f/5.6 to f/11 before they would believe me when I explained the problem. Initially, they thought the new cameras and lenses were garbage! Turns out, they just didn't understand the math...

Why Tamron even put f/32 on that lens, is a mystery to me. It's awful, except for special effects.