Luminous Landscape Forum
Equipment & Techniques => Cameras, Lenses and Shooting gear => Topic started by: Michael Erlewine on December 24, 2013, 07:53:27 am
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Received my copy of the Zeiss Otus 55mm APO lens today. Having fallen in love with its younger brother the Zeiss 135mm APO lens soon after it first came out, I was more than ready for the 55mm Otus.
I have not had time to put it through its paces, but I already see enough to agree with everything I have read about it from other reviewers as to what a great lens this is. I am primarily a close-up and macro photographer of nature subjects, most often plants. We are in the midst of serious winter here, so all the plants I have on hand are some cyclamen flowers that have seen better days.
I have spent years stacking focus, and have taken many hundreds of thousands of shots in that department. I happen to have a lot of lenses available, most of them macro or close-ups, plus other lens types that are somehow useful for close work.
Over time I found that the only lenses that really worked best for my work were lenses that were sharp and highly corrected like the Voigtlander 125mm APO, the Leica 100mm APO Elmarit-R, the Coastal Optics 60mm APO, several exotic Nikkors like the Printing Nikkors, and others.
My particular interest has been in very fast lenses that are sharp wide open or nearly so. It does not matter that the depth-of-field for this kind of lens is very shallow, since I want to stack focus with them. By stacking focus as deep as I want, I can bring out any part of the subject into sharp focus and approximate a depth-of-field effect, and know that (thanks to the fast speed) whatever I do not stack into focus will be a lovely bokeh.
Since focus stacking is a digital sampling technique, not unlike sampling audio for CDs or sampling video for DVDs, then because sampling is not perfect (which by definition it is not), there can be artifacts. Managing artifacts generated by stacking focus is complex and, thanks to retouching, is perhaps as much an art as a science.
Focus stacking, aside from a few who make it a virtue to stack photos handheld, is done on a tripod. There are several brands of decent software to process stacks of images into one final image that is as in focus as much as we wish it to be. I have tried most (if not all) of the software out there and find that Zerene Stacker is, for my work, the best all-around software, especially when it comes to retouching.
However it makes a difference (to the software) how we stack the photos in the first place. There are three popular ways to photograph stacked layers, and some are more artifact prone than others. The key is to move the entrance pupil of the lens as little as possible. Starting with the least adequate method:
(1) Mount the camera and lens on a focus rail (which is on a tripod) and gradually move the unit along the rail toward the subject being photographed.
(2) Mount the camera and lens on a tripod and turn the lens barrel (helicoid) in as fine a way as possible. Lenses with a long focus throw make it much easier to so this.
(3) And finally, the superior method (that will cause the least artifacts) is to fix the lens on a bellows (on a tripod) so that the front standard is fixed and mount the camera on the rear standard of the bellows. Then move only the rear standard to focus. This method holds the entrance pupil in the lens stationary and moves only the camera.
Not all lenses will work well with the third method and the first method (focus rail) can be too crude at times. This leaves the second method, turning the helicoid (lens barrel) as a good option unless the focus throw on the lens is too short to allow you fine movements. That is the method used in the images here.
For example, the Coastal Optics 60mm F/4 APO lens is an excellent lens, but it has a focus throw of only 210-degrees, too short IMO, plus f/4 is not very fast. While I found this lens good for copy work, it ultimately proved too much trouble for macro work, and I even tried putting it on a focus rail, etc. And then things changed.
Game changer number one was the arrival of the Nikon D800E camera body. I had been using the Nikon D3x for some time and liked the rich blacks I got out of it. However, the D800E was IMO an order of magnitude better and my focus stacking software really liked this camera, which brings me to today.
Game changer number two came with the release of the Zeiss 135mm APO lens. As mentioned earlier I had gravitated to highly corrected lens like the Voigtlander 125mm APO, the Leica 100mm APO Elmarit-R, the Coastal Optics 60mm APO, and several exotic Nikkors like the Printing Nikkors and others. I was also doing my best, short of lecturing, to tell my fellow focus stackers that the key to lenses for this work appears to me to be how highly corrected they are. I mostly was ignored and sometimes laughed at, but I persisted only because the results I was getting from APO lenses were so much better than from others, at least for stacking.
I particularly liked the Voigtlander 125mm F/2.5 APO-Lanther and although I owned both the Zeiss 100mm and the 50mm Makro-Planar lenses, I tried to point out that they were sharp (perhaps too contrasty), but their lack of correction made me prefer not to use them. The 50mm Zeiss Makro-Planar for my work was the better of the two.
With the release of the new line of Zeiss lenses and the 135mm APO, things changed. I did not run out and buy one, but I was listening for the telltale hints from various reviewers that this new lens might be a different kind of Zeiss. I finally broke down and bought the 135mm Zeiss and was amazed at what a great lens it was. It blew all my best APO lenses right out of the water, although with some the difference was close. With a lens like this, who needs most of the others, AND it was not even a macro lens!
I include a photo taken with the Zeiss 135mm APO lens (Nikon D800E), and a crop of some Japanese Beetles.
So I was ready for the 55mm Otus and knew just how to check it out. And sure enough, the 55mm is better than the 135mm (IMO) and as good as all the early reviews have pointed out, and for my work, better.
And this lens should be of special interest to close-up and macro focus stackers. My first tests, which will have to be repeated, show that a carefully done stacked photo (helicoid method) was outshone by a single photo taken at f/8 with the Otus. More startling, a photo taken at f/16 was amazingly sharp, almost as if the effects of diffraction don't appear as early on in highly-corrected lenses. I am sure they are there, but to the best of my eyesight I can't see them.
The Otus 55mm APO also takes reasonable extension without blinking. For me it works as a close-up lens, and perhaps as a macro as well.
It appears as if higher resolution cameras like 36 MP coupled with more highly-corrected lenses are a winning combination for photographers. I saw this in the Zeiss 135mm APO, but it seems further confirmed with the new Otus 55mm APO lens.
The single shots at f/8 (and even f/16) had everything sharper and with as great a depth of field as the carefully assembled stacked photos (using f/2.8). The only downside to the single-shot photo was the lack of good bokeh. Of course, bokeh was better in the f/4 stacked photo.
Up until now the stacked version of a photo (in my experience) was always sharper than the equivalent one-shot photo taken at a higher aperture setting, mostly due to diffraction. But it appears we are crossing some threshold here. I will have to let the techsperts check this out and explain it to me. Why are larger sensors and highly-corrected lenses less prone to diffraction. Diffraction is a law of nature, and we don't break nature's laws. So how does that work? What am I seeing here?
Perhaps they won't find the same result, but perhaps they will. Honestly, I might as well sell scores of my lenses and just keep these two and a buy few more that Zeiss will issue in the years to come. How about a macro lens Zeiss-Geist?
Included are some pretty rough shots taken with the Nikon D800E and the Zeiss Otus 55mm APO lens on a RRS tripod and the Swiss Arca Cube head. No attempt was made to "make pretty," but just to see how a stacked shot matched up to single shots at f/8 and f/16. Since, unfortunately perhaps, most of my work now appears on the web, I am wondering why the f/16 or f/8 single photos are not as good as the stacked shot. I believe they are, which if this fact is borne out in time means this new lens really changes how I work.
Images can be found here:
http://www.flickr.com/photos/98006906@N05/
Video tutorials here:
http://dharmagrooves.com/Photography.aspx
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Thanks for the report Michael.
I have just received my Otus this morning and will have some opportunity to put it through its pace in the coming days.
I don't doubt that the lens will be splendid for stitching as well, especially now that DxO 9 supports it.
Cheers,
Bernard
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Very interesting images, Michael. I, too, found the Otus to close focus exceedingly well, just a touch short of closest focus with a Zeiss 50 Makro. This lens, for all the hype, does seem to be quite versatile.
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Thank you for a very good article, Michael!
I am very happy with the latest version of Helicon Focus with the possibillity to
load raw-files directly into the software.
But I have never tried Zerene Stacker. Can you explain how it is better?
Also I wounder how critical do you think it is to move the focus exactly the same distance
every time? And how do you do that best? Do you use the scale on the lens or do you add an
extra scale with tape or so?
Henrik
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Henrik: Zerene Stacker has several features. One is that, like other software, it offers a couple of methods for stacking. However, unlike the others, one of those methods handles fine lines in a unique (to my knowledge) way very well.
Next, when it comes to retouching, Zerene Stacker is outstanding. It includes a feature that allows you to (temporarily) lighten the photo, so in dark photos you can see where to retouch. I need that, because I like shadows. Retouching is key in stacking focus.
It is also fast and the author Rik Littlefield is very conscientious and precise about every little thing. He also is an expert photographer, etc.
As for focus, I have to be realistic. Most of my work ends up on the web in 1024 px (long-side) format, so I need to keep that in mind. Still, shooting in 36 MP is worth the hassle of handling 100 giant TIF files to get one image, and so on.
I have not tried a robot focus rail because, as I mentioned in my first post, that is a lousy method of stacking anyway. I actually vary the distance as I move along the subject, slowing way down for anything like spheres (where gaps show easily), and speeding up in areas with not obvious things to worry about. I don't look at the scale on the lens, although the Otus is tempting. I sometimes use tape on a rail.
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Ok, that is very interesting.
I have done a lot of stacking with a camranger, a Micro-Nikkor af f4 200mm and the iPad.
Works very well with no movement of the camera at all.
After looking at the superb tests of the Nikon 200 mm f.2 I would love to try this lens for stacking.
Have you tried it?
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I have the f/4 Micro-Nikkor 200mm, but seldom use it. It is sharp, but does not compare to the lenses we are discussing here. It is not highly corrected and it shows.
At this link, the second book down is a free-e-book on macro lenses and my experience with them, as well as their specs, etc. It is getting older, but so am I.
http://dharmagrooves.com/e-Books.aspx#Photography
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However it makes a difference (to the software) how we stack the photos in the first place. There are three popular ways to photograph stacked layers, and some are more artifact prone than others. The key is to move the entrance pupil of the lens as little as possible. Starting with the least adequate method:
(1) Mount the camera and lens on a focus rail (which is on a tripod) and gradually move the unit along the rail toward the subject being photographed.
(2) Mount the camera and lens on a tripod and turn the lens barrel (helicoid) in as fine a way as possible. Lenses with a long focus throw make it much easier to so this.
(3) And finally, the superior method (that will cause the least artifacts) is to fix the lens on a bellows (on a tripod) so that the front standard is fixed and mount the camera on the rear standard of the bellows. Then move only the rear standard to focus. This method holds the entrance pupil in the lens stationary and moves only the camera.
Michael,
Thanks for a very informative post. Regarding the methods to acquire a stack, Rik Littlefield (the author of Zerine stacker) has a nice section of his FAQ (http://zerenesystems.com/cms/stacker/docs/troubleshooting/ringversusrail) covering this matter. I'm sure you know all that, but I am referring to it for the benefit of others and for discussion. Although he does not cover your method 3, but does state that using the focus ring is better in most circumstances except for extreme closeups (objects about the size of a raisin), where a rail may work better. Regarding your method 3 (focusing with the rear standard of the bellows, he does say that it is best not to move the lens, consistent with method 3.
With your method 3, the shortest bellows extension does impose limitations on focusing distance. For example, I have an old Nikon bellows whose minimum extension is 4.5 cm. The maximal extension with the Zeiss 135 mm f/2 Apo lens is 3 cm, so there is a gap between 3 and 4.5 cm of lens extension. Of course, one loses auto diaphragm with a simple bellows.
If one has an autofocus lens, method 2 (turning the lens ring) is problematic since most autofocus lenses have a short throw. However, if one is controlling the lens via software with an external program (such as Helicon Remote) it is possible to move focus in very small increments and the process can be automated. Do you have experience with this?
It appears as if higher resolution cameras like 36 MP coupled with more highly-corrected lenses are a winning combination for photographers. I saw this in the Zeiss 135mm APO, but it seems further confirmed with the new Otus 55mm APO lens.
The single shots at f/8 (and even f/16) had everything sharper and with as great a depth of field as the carefully assembled stacked photos (using f/2.8). The only downside to the single-shot photo was the lack of good bokeh. Of course, bokeh was better in the f/4 stacked photo.
Up until now the stacked version of a photo (in my experience) was always sharper than the equivalent one-shot photo taken at a higher aperture setting, mostly due to diffraction. But it appears we are crossing some threshold here. I will have to let the techsperts check this out and explain it to me. Why are larger sensors and highly-corrected lenses less prone to diffraction. Diffraction is a law of nature, and we don't break nature's laws. So how does that work? What am I seeing here?
This is an intriguing situation. The effects of diffraction can be partially overcome with deconvolution. With deconvoluiton, it helps to have a low noise image free from aberrations, and this is where your highly corrected lenses with the D800e may come in. What sharpening method are you using?
Regards,
Bill
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Bill. Thanks for the interesting comments. As for motorized rails or remote tethering of auto-focus lenses, my thoughts are simple. I have not tried motorized rails because I don't love rail stacks that much anyway. When I do use a rail, I use the Castel Q which has a Swiss Arca clamp on the top, and an Arca rail on the bottome In addition, I use the Castel-Q/XQ II Fine Adjustment Handle.
However, as mentioned, rails are not my first choice. As for tethering a lens, that means using an auto-focus lens. Most of my lenses are manual and all of the great lenses that I have are manual, so that is out. I don't have an autofocus lens that I feel is good enough compared to the Zeiss Otus 55m or the Voigtlander 125mm APO-Lanthar, etc.
Anyway, the incrementing of shots is not my problem. I have a pretty good feel for increments by helicoid, rail, or bellows by this point. One of the best bellows lenses is the Printing Nikkor 150mm lens, which is very highly corrected and just an incredible lens. But it is hard to find.
I am afraid I am always on a photo-Odyssey, one that never has arrived anywhere. For example, I have yet to print out a photo and I have been doing this since the 1950s. Well, maybe back then I printed some as a kid. Honestly, I am always trying to see if something works…. better than what I am doing at the present.
Many of the lenses I use require that I open up the aperture to focus and manually stop down to shoot, like the industrial Nikkors. As for "low noise image from aberrations," you named it. That's what we are all going for. I typically shoot at ISO 100 or whatever is the lowest in the camera. I am not skilled at finishing photos because I never feel I have one that is finished. I have shot many terabytes of photos without really doing that much finishing. Go figure.
Right now it is this new Zeiss 55mm Otus. A year ago it was the Zeiss 135mm APO, and there you go. I would really like to get the Sony A7r, but there is a shudder problem that destroys sharpness that would defeat my reason for buying one. I just looked at the Sigma Merrill DP3, but sent it back. It is a great idea, but I want it in a Nikon body with all the bells and whistles I am used to. I don't want to re-invent the wheel just for a Foveon sensor. I had the same problem with Medium Format digital backs. They were so stone-age as far as interfaces goes that I was not willing to put up with them. I still have about eleven Mamiya lenses sitting around here. I should sell them.
You get the idea. Glad to hear any ideas, so keep them coming. I don't know much about deconvolution, other than it is like trying to get the toothpaste back into the tube. Tell me about it.
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Nikon D800E, Zeiss Otus 55mm APO, Zerene Stacker
Starting to play with this lens.
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From what you see so far, is there any advantages from using the 55 over using the 135 in your kind of work?
Are they both sharp wide open or do you stop them down a bit?
Henrik
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Too early to say. Would rather have a 60mm, for context, rather than 135. Both are exemplary lenses. I am stopping them down a bit, but just getting started with this lens. I will open them up as I get the hang of it. There is a learning curve, but a great one, but still pushing beyond what I know. It is fun.
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Continuing my journey into Otus-land and the new Zeiss 55mm APO, here are a couple of photos taken this morning before my grown kids get up who are visiting start the Christmas day. I can hear my two-year-old granddaughter Emma moving around already.
One is a single-shot photo at f/8, and the other is a 35-layer stacked shot of the same flower buds.
I am going to try to shoot it over with a one shot at f/16 (or thereabouts) because there is certain to be even less difference in focus between the two shots, and this in favor of the one-shot. Even at f/8 there is quite a bit in focus and field depth.
As an old focus-stacker from way back, this kind of result brings me up short. Why bother stacking if we can have really good focus that does not require retouching (as stacked photos do), if only because they are samples and sampling is gap-prone, by definition.
So I repeat my current mantra, that with highly corrected lenses we are (at least I am) entering a new world, one that beckons to be explored.
P.S.
I have added a single-shot f/16 photo, and you can see the effects of diffraction, although it does have a lot in focus and a good depth-of-field. Still, f/8 is fine and f/16 probably a bridge too far.
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Hi Michael!
Can I ask how you store all your files?
Henrik
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I am going to try to shoot it over with a one shot at f/16 (or thereabouts) because there is certain to be even less difference in focus between the two shots, and this in favor of the one-shot. Even at f/8 there is quite a bit in focus and field depth.
As an old focus-stacker from way back, this kind of result brings me up short. Why bother stacking if we can have really good focus that does not require retouching (as stacked photos do), if only because they are samples and sampling is gap-prone, by definition.
Hi Michael,
Thanks for sharing your experiences with the Otus 55mm. My explanation for your observations is that it has to do with the relatively small output size that you require. At that size the diffraction pattern will also be small, and things will look relatively well focused, but (!) with a bit reduced modulation (MTF) as well because the diffraction pattern has a significantly large support dimension (although at low amplitude).
Cheers,
Bart
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By "output," do you mean pixel dimensions of the image. I work in full-sized 36 MP images, raw, from the D800E, so I only see them in diminutive format when I output them for web displays, like here. Perhaps I am not understanding you correctly.
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By "output," do you mean pixel dimensions of the image. I work in full-sized 36 MP images, raw, from the D800E, so I only see them in diminutive format when I output them for web displays, like here. Perhaps I am not understanding you correctly.
Hi Michael,
It is in response to your initial comments:
Up until now the stacked version of a photo (in my experience) was always sharper than the equivalent one-shot photo taken at a higher aperture setting, mostly due to diffraction. But it appears we are crossing some threshold here. I will have to let the techsperts check this out and explain it to me. Why are larger sensors and highly-corrected lenses less prone to diffraction. Diffraction is a law of nature, and we don't break nature's laws. So how does that work? What am I seeing here?
Perhaps they won't find the same result, but perhaps they will. Honestly, I might as well sell scores of my lenses and just keep these two and a buy few more that Zeiss will issue in the years to come. How about a macro lens Zeiss-Geist?
Included are some pretty rough shots taken with the Nikon D800E and the Zeiss Otus 55mm APO lens on a RRS tripod and the Swiss Arca Cube head. No attempt was made to "make pretty," but just to see how a stacked shot matched up to single shots at f/8 and f/16. Since, unfortunately perhaps, most of my work now appears on the web, I am wondering why the f/16 or f/8 single photos are not as good as the stacked shot. I believe they are, which if this fact is borne out in time means this new lens really changes how I work.
Later you specified:
Most of my work ends up on the web in 1024 px (long-side) format, so I need to keep that in mind.
This suggests to me that you are judging based on intended small sized (pixel dimensions) output, or are you judging at the 36MP level? Diffraction does not change with optics (the F-number and wavelength determine the size), other than that a more rounded aperture shape will help with a cleaner diffraction pattern and that a well corrected lens will produce a sharper image (the combination of residual lens aberrations + diffraction will be less blurry).
Cheers,
Bart
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As mentioned I work with the full image raw. I don't even much like to look at images when they are reduced, but web life demands it.
My point is that highly corrected lenses in my experience seem to do better as regards retarding diffraction than do poorly corrected lenses. Of course, I may just be seeing things, but what I see so far is that with these new Zeiss lenses it seems possible to get away with higher apertures instead of stacking focus to get the effect of depth-of-field. I am just wondering what other Otus 55mm users are finding in close-up work.
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I've bee following your posts regarding stacking and your shiny new Otus. You are making some exceptionally intriguing imagery.
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As mentioned I work with the full image raw. I don't even much like to look at images when they are reduced, but web life demands it.
Hi Michael,
I see, so you are getting the impression from the full sized images.
My point is that highly corrected lenses in my experience seem to do better as regards retarding diffraction than do poorly corrected lenses.
That may seem the case, but it's just that the combination of residual lens aberrations and Diffraction blur is multiplicative, the MTFs (modulation transfer functions which are both between 0.0 and 1.0) multiply. So when the lens is better corrected, the combined effect will improve, even if the diffraction component is the same. Therefore, what you are seeing is the improved lens corrections, not the diffraction, producing a better mixed result.
Cheers,
Bart
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I understand. Diffraction is like gravity, a law of nature. I have been getting deeper into APO lenses for years, although there is no standard for correction. Some of the exotic industrial Nikkors are highly corrected, like the Printing Nikkors, which were used for scanning movies years ago on very expensive film scanners. These lenses costs something like $12,000 apiece. I have three of the four made, the 95mm, the 105mm, and the 150mm, with the 150mm being the best of the lot IMO. There is also a 75mm that I have never seen for sale. I use these on a bellows. They are very corrected, as are these two new Zeiss lenses.
So, yes, the improved lens correction carries us farther into the higher end of the apertures then uncorrected lenses do. I saw this early on with the Voigtlander 125mm f/2.5 APO-Lanthar, the Leica 100mm Elmarit-R APO, and the Coastal Optics 60 mm f/4 APO, and others. But the huge difference between those lenses and these two new Zeiss lenses amounts for my work in a giant step forward, one that might just carry me away from stacking focus for the most part. Anyway, these new lenses are an adventure.
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You get the idea. Glad to hear any ideas, so keep them coming. I don't know much about deconvolution, other than it is like trying to get the toothpaste back into the tube. Tell me about it.
Michael,
I am glad that you entered into discussions on this forum since you have a great depth of technical expertise and artistry. You might look into deconvolution techniques, which can impose a great deal of trouble, but no less than that involved in stacking 30 images.
To get an idea of what deconvolution can do, take a look at this thread (http://www.openphotographyforums.com/forums/showthread.php?t=12555). Bart's original post is here (http://www.luminous-landscape.com/forum/index.php?topic=45038.msg378541#msg378541). Bear in mind that this is merely a demonstration of what deconvolution can do with a known PSF (point spread function), which is merely a function describing how the image was degraded. One can approximate a PSF with a gaussian function. The radius used for the deconvolution varies with the f/stop and one can estimate it with Bart's tool (http://bvdwolf.home.xs4all.nl/main/foto/psf/SlantedEdge.html). One can use the results to calculate a PSF (http://bvdwolf.home.xs4all.nl/main/foto/psf/PSF_generator.html) that one can use in various freeware programs or with ImagesPlus (a paid astronomical program that is also useful for processing terrestrial images).
Once the PSF is derived, you could use as a preset for processing multiple images. I have the D800e and the Zeiss 135mm f/2 Apo and will try to publish some results on the forum once the holidays are over and I get the time. Results from others are welcome.
Merry Christmas to all.
Bill
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I looked lightly through the deconvolution and found it, of course, convoluted enough to deter me from whatever the next step to trying it might be. Perhaps there will be some software that does this that is easy to use.
Perhaps you will do some of this and let us know how it comes out. I would like to learn more.
Meanwhile, these new Zeus lenses have opened a degree of freedom that was not apparent to me before, and I will see how far I can push that.
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...these new Zeus lenses have opened a degree of freedom that was not apparent to me before...
Zeus? I'm setting up an altar...
Jim
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I looked lightly through the deconvolution and found it, of course, convoluted enough to deter me from whatever the next step to trying it might be. Perhaps there will be some software that does this that is easy to use.
Hi Michael,
There is, in the shape of a Photoshop Plugin called Focus Magic (http://www.focusmagic.com/index.html). I've heard that the price will increase next year, so check it out soon.
Another option is Topaz Labs Infocus (http://www.topazlabs.com/infocus/), also a PS plugin, but it can also be called directly from e.g. Lightroom and others. They also have a plugin called Detail 3 (http://www.topazlabs.com/detail/), which also has a 'Deblur' control with fewer options but in addition it offers several levels of detail enhancement that's also very useful for Macro photography.
Cheers,
Bart
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Thanks. I will check those programs out.
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I started doing close-up photography in 1956 when my dad gave me a Kodak Retina 2a, a light meter, and some close-up lenses. Over the years, but more particularly in recent years, I have been on a little Odyssey to find sharp lenses. I have written many articles about this, so I am not going to repeat that here. Those of you who might like to read some of that will find it here:
http://dharmagrooves.com/pdf/e-books/Close-Up_Macro_2012.pdf
I use Nikon cameras for the most part. I just like them, but I can see we are in a major transition phase with cameras or at least a serious segue. I just ordered a Sony A7r, and sent back a Sigma Merrill DP3. The DP3 was just too much trouble. If they would offer a large Foveon sensor in a Nikon-like body (and interface) with an A7r EVF, I would like to work with that, but until then the DP3 is just a bridge too far.
As mentioned in earlier posts, my quest for sharp lenses led me gradually through some of Nikon's finest lenses and finally beyond Nikon into Leica, Voigtlander, Zeiss, and other brands of lenses. In the end I found that sharpness was not simply what I thought sharpness was supposed to be, but rather that it depended on how well the lens was corrected for a variety of things, but particularly for color.
As we know, when color comes through a lens, each of the main colors (red, green, and blue) focus in the plane of the camera's sensor at a very slightly different depth. In other words, they don't land on the same plane (sensor), and this discrepancy causes what is called chromatic aberration and there are other anomalies too. This shows up in our photos in what is called color fringing, little red-green and blue-yellow fringing on sharp edges. Well of course we photographers hate this, but we are also kind of used to it.
Now this color fringing was not generally associated with sharpness until recently, although by definition it absolutely made the resulting photos less sharp – fringed. It is possible to create lenses that manage to bring the red, green, and blue colors to focus on the same plane, the sensor, thus removing chromatic aberration. Such corrected lenses are the APO or apochromatic lenses like the two new Zeiss offerings 135mm and 55mm APOs. But this process is very expensive and so are the resulting APO lenses.
Most manufacturers of lenses don't go to the trouble (and the resulting expense) of offering APO lenses, but some do, and I bet we start to see more of them now that Zeiss has hit a home run. But years ago I gradually realized that these APO lenses produce what I call "sharper" images, because the lenses themselves are more highly corrected, and so on. APO lenses are now coming to the fore as they never have before.
I have been using (mainly) APO lenses for many years and that is why some of my work is "sharp." Another thing I do is stack focus, which is nothing more than taking a series of photos, each in sharp focus, from the front of a still object (like a flower) to the rear, and then combine these photo layers to make a single image that is in focus from front to back. So those are the two techniques I mainly use, focus stacking and APO lenses. And I like to use very fast wide-angle APO lenses wide open so that whatever I don't stack into focus is a nice bokeh. I paint focus with the narrow depth-of-field of a fast lens.
I should be putting my new Zeiss 55mm APO through all kinds of tests, but what I find myself doing is indulging the artist in me through this great lens. I will explain.
I don't just want a photograph to be a mirror image of what I see outside in nature, but rather I want my photographs to be a mirror image of how my mind sees this natural beauty. So, by definition, I am an impressionist. I want to see for myself (and share with others) my impression of the beauty and awe I find in the natural world.
And as a naturalist since I was six-years old, I am also some percentage a scientist. I want something in a photograph to be in high focus (clarity), but not everything. I don't just want a "snapshot" of what is "out there," but rather a painting in light of what impresses my mind. So I try to get one part of a photo in clear focus and then paint with a broad "light-brush" the background as if it were a painting by one of the great French Impressionists.
At heart, my work says to me: "Look how real this dream of life we are living appears."
[Photo taken yesterday with Nikon D800E and Zeiss Otus 55mm APO (Zerene Stacker) that shows how I like to combine clarity and dreams.]