I have been stacking focus for many years now, so I’m no stranger to this technique. And the track of my learning curve (more like a spiral) has been fueled by my using better and better corrected lenses (APO) to enhance the stacking. In other words, the more finely corrected the lenses, the more careful I have to be in stacking, and on around. It’s like a Catch-22.
I get lots of emails and messages about my photos. And not infrequently (at least from photographers) is the question as to whether I have tried one of the automated focus rails. In the past, I have taken a certain amount of pride in pointing out to these folks that I can stack quite well manually, thank you very much. I had no intention of varying my technique.
Yet, as I pointed out above, the circular spiral of finer lenses and precise stacking led to more and better apochromatic lenses, like the Zeiss Otus series, the APO-El Nikkor 105, the Leica Elmarit-R APO 100mm macro, and so on. I pretty-much took these fine lenses in stride, hopefully learning to use them more and more skillfully.
Then comes the Schneider Macro Varon 85mm industrial lens. I had kind of heard about this lens on and off for some time, but never had seen one come up used on Ebay and even trying to get availability and a firm price from the manufacturer and distributors was difficult. It was almost as if they did not want to sell to me because I was not a company that required industrial lens for line-scanning. I wrote them. I called them on the phone.
A more detailed story about the Macro Varon would require a separate article. Suffice it to say that a good friend of mine, another photographer, sent me a FB message telling me that a Macro Varon just came up of Ebay and at an attractive price at that. It took all of perhaps one minute and I had bought it. It was not an impulse buy, because I had decided to get one quite a while ago, just not pay the retail price of about $4500. Ouch!
The Makro Varon is a very highly corrected lens, certainly worthy of the name APO. However, perhaps most remarkable was that this was a lens built for a wide range of magnifications, which is unusual for industrial lenses, which usually have a very limited magnification range at which they are at optimum sharpness. The Macro Varon even has a separate ring to compensate for whichever reproduction-ratio is used, actually moving the inner lens elements around to accommodate that reproduction range. And, interestingly enough, its specs showed me that it could easily outperform the sensor of my fairly new Nikon D850. “Hmmmm, I mused. I’d like to see that.”
And see it I did and pretty quickly too. But such a revelation soon led me to rethinking my bias against automated focus rails. It was not that I could not stack well, but I continue to get older and I am old enough as it is, and the little bumps, jars, and vibrations caused by me began to be more visible; they got in the way.
Anyway, back to this blog. So, there I was, reading about the StackShot, when before I knew it my finger was hitting the return-key to order a copy. And to my surprise, the company (Cognisys) was right here in Michigan, only just up the road from where I live, in Traverse City.
So, it was only a day or so before the automated-rail turned up at my door. However, learning to use StackShot was a bit of puzzle. It actually is very simple, but the manual is SO complete that finding the simple in it is hard. At least that’s how it struck me. I just wanted to get going right away and stack something, but although eventually that was easy, at first it was not so.
And also, this device is meant for many kinds (or ways) of stacking. It took me a while to figure out what the name for what I wanted to do was. I finally did (Automatic Distance) and, as mentioned, it could not be simpler. Well, it could be explained more simply. LOL. As a software developer myself since the early 1970s, I recognized the kind of manual that indeed was precise, but is no beginner’s guide. I told them so.
The problem was, IMO, how do I find what increment or step makes sense for the kind of close-up focus-stacking that I do. I don’t need the kind of detail one needs for stacking a bee’s knees, but I do need enough overlap of images to make the rendering of the stack smooth with no banding.
Of course, I called the support line at Cognisys and spoke with a very nice person, only too willing to help. The problem was that at each question, each point where I was stuck, he pointed out that this or that particular choice was variable, very variable. So after fifteen minutes or so, I was right back where I started from, having to figure it out for myself. What’s new? Story of my life! LOL.
And it took a while for me to run many stacks at different step-sizes to find a step-size that gave me what I was looking for and not one that took all day by over-stacking what probably couldn’t be seen. I wasn’t stacking a microscope image, but just a flower or two.
I messaged Rik Littlefield, creator of Zerene Stacker, the stacking software I use, and asked him about over sampling. His response was that it won’t harm anything to make too many images, but it might add a wee bit of extra noise.
After a few happy days with StackShot, here is where I am at. So far, it looks like the more detail you can get with the smaller increments with Stackshot, the better the result, within reason.
StackShot likes to work in thousandths-of-an-inch or in millimeters or fractions thereof, your choice. I found myself working with MLS, thousandths of an inch, a setting of 20 Mls seems pretty good. 10 MLS is slightly better, but perhaps not worth the extra time, etc. A lot depends on keeping natural light even, which is hard with variable cloudiness.
My thoughts on using the StackShot automatic-rail are positive. I have stacked for many years, always barely touching the focus barrel or whatever mechanism as required. I got pretty good at it, but also made little accidental bumps and knocks, which have never helped at all. And, as I drill down on these ultra-sharp industrial lenses that can challenge the sensor of even the Nikon D850, there is less room for user-caused error and a greater demand for regular precise increments.
After many years of focus stacking, my most valuable learned skills are in setting up and composing the shot, although I have always done my best to move carefully through all the steps that focus-stacking requires. However, having tried out StackShot, I am convinced it has a lot to offer me in stability and consistency, leaving me more time to consider what shot I want to take. I am enjoying that.
I have a fair amount of testing the Stackshot yet to do, but I am already getting a handle on it. By testing various step-sizes, I am already converging on what seems to work for me. I’m not doing photo-micography, but rather just simple close-up and macro photography.
Of the many options that StackShot offers, the one I seem to be gravitating to is Automatic-Distance, which allows me to choose the granularity, the step-size, that works best for my work. In other words, I have one main step size that will be applied no matter what scope or distance I want to cover. Should that not be fine enough, I can easily make if finer, etc. The only caveat might be with spherical objects, where following the curve demands finer steps, IMO.
So, the step sizes I have settled on should work. Physically, the StackShot is very well made, meaning it is robust, as strong or stronger than any other focus rail I have and I have ten or so. Its vertical profile for my camera is low, about as low as it could be and I have fitted it with my favorite RRS Arca quick-release clamp, the one with a larger knob. I can see no way that this is not better than what I have been doing myself by hand.
And the program allows me to introduce all kinds of latency time, which I have done, so that at each movement of the auto rail, I take a second or so to let any vibrations created by the mechanism movement subside.
The only problem, which has nothing to do with StackShot, is that since I use natural light, on a variably-cloudy day the lighting changes from moment to moment and affects the stack. To counter this, I would have to be standing there, slightly modifying the shutter moment-by-moment to keep the light stable. That kind of takes the auto out of automatic, but that’s the price we pay for natural light. It varies.
So, my initial impression of the StackShot is not only good, but very good, almost something like “where-have-you-been-all-my-life?” good. I like it.
As for taking the time I am used to spending stacking focus at the camera away from me, which I traditionally associate with meditative absorption on my part, it does not seem a problem. My hard-won skills are seeing the shot and setting up for it. With StackShot, I do the creative work and let an expert step through the mechanics while I do other stuff. Makes sense and seems fine.
StackShot is easily rough enough to take into the field, provided you realize that it is heavy and if you don’t have any wind. Here in Michigan, I wait to see each day if there is no wind at first light. Rare, but it happens.
A Hidden Surprise
Surprise, surprise! There is almost always a surprise with new equipment. Using stackshot made one thing very clear. By standardizing the process of focus stacking (the mechanical part) all lenses were treated equally.
It’s true that I always did my best to incrementally stack focus as carefully as I could. But, I cannot pretend that on any given day, I may have stacked looser or tighter, even or less even. I can only guess at the variation.
But one thing is clear so far from using the StackShot and that is that the regularity of increments (the step size) reveals more clearly than I have ever seen the true or actual difference between any of these highly corrected lenses. It is clear that some of these lens differences were veiled by the more organic (sloppy) process of stacking by hand and not by auto-stacking.
However, by regulating the stacking process, it creates a much more level playing field. And I found it very easy to see the differences between lenses, many of which I could never before be certain about.
And so, whatever else auto-rail stacking provides (and there is a lot) a wonderful bonus in allowing me to see more clearly than ever how lenses differ, something I have always strained to see (regardless of all the graphs) for myself. By stacking in a more regulated manner removes (at least for me) a veil that has been obscuring these difference all of this time.
Below are a couple of tables that might be useful. StackShot likes to work in thousandths-of-an-inch or in millimeters or fractions there of.
1 Millimeter = 39.3701 Thousandth of an Inch
1 thousandth of an inch in is equal to 25.40 μm
Thousandths-inch TO MILLIMETER
10-mils = 0.254 Millimeters
15-mils = 0.381 Millimeters
20-mils = 0.508 Millimeters
25-mils = 0.635 Millimeters
30-mils = 0.762 Millimeters
35-mils = 0.889 Millimeters
39-mils = 0.9906 Millimeters
39.37 mils = 1 Millimeter
MILLIMETER to Thousandths-inch
.25 MM = 9.84 Mils
.333 MM = 13.11 Mils
.5 MM = 19.685 Mils
.666 MM = 26.22
.75 MM =29.5276 Mils
1 MM = 39.37 Mils
1.25 MM = 49.2126 Mils
1.5 MM = 59.055 Mils
2 MM = 78.7 Mils
2.5 MM = 98.42 Mils
3 MM = 118.11 Mils
3.5 = 137.8 Mils
4 = 157.5 Mils
4.5 = 177.2 Mils
5 = 197 Mils
Here are three example images, both done with StackShot, one with the Schneider Macro Varon f/4.5 and another with the APO-El Nikkor 105mm f/5.6. A third one is with the Nikkor “O” CRT lens. Also, a poor-quality shot (shot at night in bad lighting) of the StackShot controller (Vecro-ed to a post) and the basic StackShot setup. Not the RRS Quick-Releas Clamp with the large knob.
Edited by Dallas