The value of highly corrected (apochromatic or APO) lenses is gradually being understood by photographers outside of a small group. Sharpness is not just a matter of acutance and resolution. All of the purple and greenish fringing chromatic aberration) caused by colors not focusing properly on the camera sensor totally affects what we call sharpness. IMO, proper color focus (APO) is what puts the “sharp” in the tip-of-the-top of photographic sharpness – the finishing touch.
The problem of juggling a group of lenses inside a lens barrel so that the colors are properly aligned and focused at the sensor is not trivial. It costs real money to get a pristine example of an apochromatic lens. And it’s not surprising that the APO lenses we do have didn’t originally come from satisfying mainstream photographers, but rather from industrial needs where they simply had to perform.
For example, the now classic Printing Nikkor lenses were designed for film scanners, mostly to make crystal-clear copies of our favorite movies back in the celluloid days. These lenses are said to have cost $12,000 a pop. They turn up regularly on Ebay now for a couple or a few thousand dollars as the industry goes digital.
Even then, these specialized lenses are just that, specialized. They typically don’t go to infinity, but are geared to perform at their optimum quality in a very narrow magnification range. Not only that, but most are best used wide open (at full aperture), which is very unusual for your typical photography lens, where optimum sharpness more usually is reached at something like f/5.6 or so.
So, those of us who collect and play around with these industrial lenses end up with a rag-tag crew of lenses, each with its own idiosyncrasies. No two are the same. And even more unorthodox are the mounts! These lenses are not made to be mounted on a camera flange, but instead on one kind or another industrial machine. It’s no wonder that people like me have boxes and boxes of adapters, screw mounts, microscope mounts, and what-not. I still have lenses sitting around that I have been unable to find a mount for!
The “Why bother?” is because many of these lenses are so highly corrected that the photos they produce, even in their restricted reproduction-range, are often better than anything we can produce using the general quality of lenses on the market. This is (finally!) changing as in the last few years there has been a turn toward higher quality lenses for general use. One company who has led the charge is Zeiss with the remarkable Otus series of lenses and Sigma is now producing a series of what they call their “Art” lenses that also have higher quality.
And, as mentioned, these industrial lenses are much more difficult to use. They require special mounts and many only work well on a bellows system and, even then, only within a highly restricted magnification range. Not everyone wants to go through all that.
You don’t just slap these industrial lenses on your camera for a number of reasons. For one, they have no focusing helicoid on them. They don’t reach infinity. They don’t tend to work, as mentioned, except in a very restricted working range, sometimes just inches!
Yet, as mentioned, if you can manage them, these industrial lenses are capable of producing some very fine images, which is why photographers like myself find ourselves using them. And, even then, the average photographer is not going to find much use for a lens that needs to be used wide-open. The depth of field for many of these lenses is razor thin, so unless you want to feature the pink nose of gnat, who would use it?
Well, the answer to that question is that those of us who stack focus would use them. By stacking many layers of thin focus, one on the other, we can create an image in high focus and with as large an area as we are willing to stack. With stacking focus, these oddball industrial lenses become magic wands that literally paint focus on a canvas of bokeh, those areas of an image that are attractively out-of-focus. Overlaid on a gentle bokeh is a crystal-clear image in perfect focus. In other words, by painting focus, the photographer decides where the eye goes rather than, as with a traditional photo, our eye goes to the plane and point of focus dictated by the focused lens.
Here is a photo taken with an industrial lens (Nikkor “O” CRT) that was designed for examining the curved surface of a computer CRT monitor. The lens is wicked fast wide open and what it does not focus on it easily renders out-of-focus as a gentle bokeh. As you can see in this photo, that drop of nectar at the tip of the Calla Lily is placed in high focus, leaving the rest nicely out-of-focus. This is what these industrial lenses can do, at least in the hands of those of us who stack focus.
Where do we go from here? I can’t see the qualities of these somewhat rare (and certainly expensive) industrial lenses making their way into the popular photography market. They will continue appealing to a niche market as long as scanners, copy machines, and projectors need lenses.
There are some signs that the qualities of these scanning lenses are beginning to appear as industry lenses with a wider gamut. The Schneider Macro Varon APO f/4.5 lens is an example of an industry-able lens that has high quality over much wider magnification range. Perhaps lenses like the Macro Varon will begin to seep into close-up and macro photography or some company may choose to make such a lens just for general photography as opposed to just industrial applications.
There is a sea change going on as regards the color excellence of lenses, trending toward better quality and more highly corrected lenses being available. It’s about time! However, I’m still waiting for high tide.
[Photo by me using the Nikkor “O” CRT lens.]
