The State of Stacking Focus

Notes on focus stacking
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The State of Stacking Focus

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I have stacked focus for many years, moving up through many different cameras, mostly Nikons, but also a medium-format Mamiya, and several mirrorless cameras.

The sweet spot in all that work has been the Nikon D800E, with its 36 MP and no AA filter. I have even looked into stacking video clips and had a special frictionless slider built for that purpose. That is a separate article.

In the course of all of this I have shot many hundreds of thousands of photos, plus published several books on focus stacking and scores of articles, and created some 20+ video tutorials, all of them free of course. I would never want to be a professional photographer. It is far too difficult these days. I have made my living in other ways. And now to the point:

Years ago I went on an odyssey to find lenses that were "sharp," whatever that means, lenses that had high resolution. I have written exhaustively on this and in the beginning the experts either ignored me or made fun of me. And here is why:

My research and tests showed me that the search for sharpness finally turned on how well a particular lens was corrected. I gradually found my way to more highly corrected lenses. My point is that putting lenses together of equal sharpness, the sharpest lens (again and again) IMO turned out to be the lens that was most highly corrected for the various aberrations, and so on.

I ended up using lenses like the Coastal Optics 60mm f/4 APO forensic lens, the Leica Elmarit-R 100mm APO macro, and especially the legendary Voigtlander 125mm f/2.5 APO-Lanthar, and others. These are the lenses I found were the best for focus stacking or any other work. I also got deep into the various Nikkor industrial lenses, lenses like the four Printing Nikkors, the El Nikkor APO lens, and others. They were all highly corrected lenses.

However, I still could not get much of a witness to my claim that sharpness in lenses (all things being equal) finally turned on their degree of correction. I assumed these great lens experts knew what they were talking about. It turned out that this wa s not always so.

All of this changed when Zeiss brought out the first in their series of special APO lenses, the Zeiss APO Sonnar 135mm f/2 lens. By this time I had accumulated a great number (like 80) of very high quality lenses, for the most part close-up and macro lenses. The Zeiss 135mm APO had a minimum focus distance of 2.62 feet (0.8 mm), so (since I am a close-up photographer) I at first dismissed it out-of-hand as a lens I would ever purchase, not to mention that it cost $2000.

But over time, what I read about this lens led me to believe that indeed it was highly corrected, so much so that even with extension tubes the results were very good. I am not a believer in adding glass to good glass, and I have tested this. I own about every possible diopter, teleconverter, and so forth that is available and none of them ever improved a shot. I own them, but avoid them at all costs.

Still I was intrigued by the reports I was reading on the new Zeiss 135mm APO Sonnar, so finally one day I just pulled the trigger and ordered one.

I soon found out that the 135mm Zeiss was indeed exceptional, so exceptional that it outclassed all of the highly corrected lenses I already owned. And although the near focus distance was a distant 2.62 feet, I found that I could crop out and resolved fine detail better than with any of my other lenses. And the color and contrast were great.

I already owned both the 50mm and 100mm Zeiss Makro-Planar lenses. And while these two lenses have a sterling reputation, I never used them because they simply were not well enough corrected and I could always see the difference. Of the two, I liked the 50mm Zeiss Makro-Planar most, perhaps because I had so many other fine lenses around the 100mm mark. Anyway, those lenses sat on the shelf, and I had come to assume that Zeiss lenses were very 'contrasty' and lacked correction. This probably was the main factor that kept me from trying out the Zeiss 135mm earlier than I did.

Anyway, suddenly here I was using the Zeiss 135mm APO lens all the time and being knocked out by its performance. I didn't bother adding extension to it, but found that I could crop out what I wanted from a 36 MP shot on the Nikon D800e and use that.

Then along comes the second in the new Zeiss series, the 55mm f/1.5 Otus Distagon lens in Nikon mount. By this time I was already a believer in this new series and, despite the price tag of $4000, I pre-ordered that lens as soon as it was announced.

Again the Otus 55mm APO lens was a total winner, producing just incredible photos. And finally I am coming to the point of all of this writing:

The new Zeiss lenses, especially the 55mm Otus, are so good that I found I could push the f/stop much higher than I could with other lenses. I had learned, as we photographers all know, that high f/stops (f/11,f/16, f/22, or what have you) flirt with diffraction, with the result that sharpness and the depth-of-field attained is washed out by the softening of diffraction. And I know that is a law of nature, like the law of gravity, and that we don't break the laws of nature.

That being said, I found that I often could shoot at even f/16 (the highest f-stop on the 55mm Zeiss) and, depending on the subject matter, I got incredible depth-of-field and paid a very small price for it in diffraction results. How could that be?

And I tested many single shot photos with the Zeiss 55mm against a multi-layer (100 layers) stacked photo from the same lens and the single shot was acceptable as a "stacked photo." Of course there are tradeoffs.

The stacking process, in post, messes with the color and introduces various artifacts, so the retouching in post of complex stacked photos is pretty much mandatory. So here I was comparing a carefully stacked photo of many layers to a one-shot photo taken with the 55mm Otus at f/11 or f/16 and choosing to go with the one-shot photo. That was news!

Now, with a one-shot photo I could not push focus as deep as I could by focus stacking, but the depth-of-field was deep enough to capture the effect that I liked from stacking focus. And prior to this I had been going exactly the opposite way, which I will sidebar here.

Since early-on I found that I could not push the aperture into the high numbers without suffering diffraction consequences, I had gone in the opposite direction. I developed a method using the best wide-angle lenses that were sharp wide open and were very fast, ones that had an extremely narrow depth-of-field. And I used that very sharp depth-of-field like a laser paintbrush to paint in (by doing many stacked layers) just that part of the image I wanted in extreme focus, and let the natural bokeh that fast wide-angle lenses provide just run wild in the background.

This produced an impressionistic and often ethereal look to the photo. I loved what you can do with sharp wide-angle lenses (of which there are few great ones).

And suddenly with these two new Zeiss APO lenses, my original dream of finding the holy grail of natural depth-of-field focus was coming true. I could take a one-shot photo and have outstanding depth-of-field with one shot. The only downside I found is that, by definition, I then lost the dreamy background bokeh that wide-open lenses bring. However, if I wanted that, all I had to do is shoot one blurred background photo and paint it into my one-shot photo. I did that maybe once.

With this method, the endless artifacts necessarily caused by stacking photos were gone. Keep in mind that focus stacking, like making music CDs or video DVDs, is just another digital sampling technique, meaning that we sample, taking some of the image, but by definition, leaving gaps behind of what we don't record. And those areas not sampled are what cause, naturally, all of the gnarly artifacts that we focus stackers have to retouch out. Even worse, the stacking process messes with the color, and that is even harder to restore, if it is even possible.

So, here I stand at a crossroads, with my well-worn path of focus stacking heading off one way, and going another way is simply learning to take almost perfect one-shot photos with these highly-correct Zeiss lenses. The truth is that I already find myself walking the path of the one-shot photo, because….. the results are better. Ultimately all of my passion for photography depends on capturing in a photo the beauty of what I see in my mind. I am not a technique person for its own sake. Never was. I use technique to get an effect.

I go where the beauty goes, and that seems away from so much focus stacking. Sure I will stack product photos or photos where pushing depth-of-field is paramount, and lack of perfect color is not important.

But that aside, the purity of color, sharpness, and lack of artifacts makes single shots with these new Zeiss lenses the obvious choice. In fact, I am already culling through my collection of great macro lenses, many of which I will never use again because they lack the quality I can now always get with the new Zeiss lenses. I keep them around just to say I have them, but I never use them and never will again. So I will sell them and buy whatever next Zeiss APO lens comes down the pike, in this case an 85mm APO, I am told.

So that's my story. It should interest those of you who stack focus.
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