Enhancing Sharpness by Auto-Stacking

[Michael Erlewine]

Since I’m always on the lookout for sharp and well-corrected lenses, APO if possible, over time I have kind of run out of lenses for the Nikon mount to find. I am sure there are some out there, but I don’t know where they are or can’t (or won’t) afford them. LOL.

Another approach is to find ways to enhance the APO lenses that I already have. Let’s take my old standby the Voigtlander 125mm f/2.5 APO Lanthar, still the best all-around macro lens that I know of. Other lenses best it in this or that feature, but when you add up all the features, the CV-125 still comes out on top every time.

One of the areas where the CV-125 didn’t quite match up to some of the best APO lenses is sharpness, whether you consider sharpness as acuity and resolution or, as I do, add to that how well corrected is the lens is for the various aberrations, etc.

Yet, lately I did find another way to better compensate for some areas that the CV-125 fell ever so slightly short. And that is by using the lens on an automatic focus rail. I use StackShot, but there are also others out there.

If I mount the CV-125 on the Nikon D850 on the StackShot auto-rail and set the step increment on the finer (shorter increment) side, the CV-125 very much benefits from regular short increment steps and focus stacking.

The net result is to bring out or compensate for the very slight lack of sharpness I see when I stack the CV-125 by hand by turning the focus ring of the lens directly.

My point is that using precise auto stacking brings out the sense of sharpness with this lens and I would imagine with any other lens.

Here is a photo taken with the Nikon D850 with the CV-125 lens mounted on the StackShot auto-rail. To my eyes, the degree of refined sharpness is a little better than what I can do by hand. This image is reasonably sharp.

So, for we focus stackers out there, using auto-rails may be a way to get better “sharpness” without having to spend a fortune for better lenses. Of course, how would I know because I have spent way too much on buying really well-corrected lenses. LOL.

[armando_m]

I think another reason for a well corrected lens is the ability to get better colors?

obviously sharpness looks beyond real in the picture you are sharing here

[Michael Erlewine]

I think another reason for a well corrected lens is the ability to get better colors?

obviously sharpness looks beyond real in the picture you are sharing here

That's what this quote from my posts points at:

"add to that how well corrected is the lens is for the various aberrations, etc."

[Frank Fremerey]

Michael: Do I understand and see correctly that you produce significantly less stacking artifacts with precision stepping?

[Michael Erlewine]

Michael: Do I understand and see correctly that you produce significantly less stacking artifacts with precision stepping?

You could say that. Stacking, like digital CDs and DVDs, is a product of sampling. Stacking is not "analog," so to speak. I once had a special focus rail built for me that allowed me to slide the rail while taking essentially video in hopes of getting a more seamless result, but it was too fraught with user error. However, it is a nice paperweight. LOL.

The finer the sampling, the finer the result, except that the processing of stacks introduces its own "noise" and artifacts, so like everything else, there is no free lunch.

My point in this post is that by stacking automatically and refining the stepsize gets us a little more out of the lenses we have than by manual stacking, at least for me.

[Frank Fremerey]

Thank you for your clarification. Are you awake 24/7???

[Michael Erlewine]

Thank you for your clarification. Are you awake 24/7???

Something like that. LOL.

[Dr Klaus Schmitt]

Excellent result Michael and quite expected results, the ZERENE Stacker software is seemingly pleased using equidistant taken images!!