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Author Topic: The Zeiss 135mm API, f/2 and Depth-of-Field  (Read 4855 times)

Michael Erlewine

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The Zeiss 135mm API, f/2 and Depth-of-Field
« on: March 24, 2015, 07:08:13 am »

I can read the various MTF and other lens-testing charts, but they are only as meaningful in my work as I can implement them in the studio or field. In other words, I am not much of a lens tester myself, except though actually using the lens for my own work. I am certain that any given lens reaches greatest resolution at a certain f/stop, just as the experts tell us. No doubt. However, what I really want to know is about what kind of curve the particular lens creates from its widest to its narrowest aperture and how does that curve affect my particular work. That’s the curve I actually use. In other words, is it “sharp” wide-open or does that sharpness start a couple of stops later, and how long is that sharpness maintained? What kind of curve do we have, sharp or gentle?

As someone who stacks focus, I don’t stack focus at the same aperture that I use for taking a traditional single-shot photo. With a one-shot photo I tend to, of course, push the aperture higher (narrower) to get as much depth-of-field as I feel I need for a particular shot, which often is as much as I can get without degradation of the image through diffraction. Yet when I stack focus, I don’t worry about using a narrower aperture to get my depth of field, but rather I use focus stacking to create the apparent depth of field.

So, for focus stacking I want a single aperture on the lens-curve that marks the point of greatest resolution for that lens. In summary, I don’t try to stack with narrow apertures, but almost always with a single aperture for the lens that is considered its peak-resolution, what commonly is called “sharpness,” although that is a rather nebulous term. That way every increment of the stacked layers has maximum resolution and therefore the resulting stacked images shares that too.

Not to be confusing, but sometimes I stack not at the point (aperture) of greatest resolution, but just a little higher (narrower) if I am trying to create a little additional faux micro-contrast for that image. I take advantage of the greater depth-of-field obtained at a narrower aperture and record the additional depth-of-field as if it were greater acutance – micro-contrast. I am still undecided whether this actually helps, but it is a concept I am playing with. Normally I stack at the aperture that the testers (or my eyes) tell me has the most resolution for that lens and leave it go at that. The point here is that I come up with my own idea of what aperture curve will work for the job at hand, i.e. what I can get away with.

All photographs IMO are impressions, our own mental and psychological impressions of what we see out in the world, given the caveat that much of what we see, our impressions, come not from the outside, but from our own mind and approach. Because focus stacking is a form of lossy sampling, a stacked photo is almost an impression of an impression, so to speak. I don’t easily fall into believing that what I am photographing out there in the world has a reality greater than my own impressions and approach. Let’s take the recent Zeiss 135mm APO as an example, and the following are just my thoughts on how I use this lens for close-up photography.

The Zeiss 135mm is sharp wide-open, so I don’t have to add a couple of f/stops to achieve better resolution. With this lens wide-open, I get a depth-of-field (DOF) that is razor sharp. With that ultra-thin slice of DOF, I can literally paint focus, layer by layer, until I create what we could call a block of focus that represents what I want in that image to be sharp and in-focus. Because the lens is fast and wide open, whatever I don’t layer-paint is automatically blurred or part of the bokeh of the image. Note that this is the opposite of much traditional advice for focus stackers, i.e. that we push the lens as high as we can without suffering too much diffraction and then stack. I am going against tradition here because I like the results better. Now, back to the Zeiss APO 135mm lens.

With traditional one-shot photos, when I am not stacking, I find that from the Zeiss 135 APO I can get usable resolution and acutance all the way to up to something like f/13, which is a long way. Yes, by then I am recording diffraction that bothers me (and way before that), but I often can get by with it. If I don’t need peak sharpness for the particular subject, I can shoot at f/16 and inject some little bit of needed clarity or contrast in post. Beyond f/16 I am getting too much diffraction and image-degradation to venture there.

Since I am primarily a close-up photographer (rather than a macro photographer), much less a micro-photographer, the lack of extreme detail at f/16 with the Zeiss 135mm APO is often acceptable, diffraction and all. In fact, I have an ongoing battle going on within me whether to do a lot less stacking and a lot more taking single-shot traditional photos.

I am also experimenting with what I call “short-stacks,” where I take two or three shots that capture the particular areas in a photo I want to be in high-focus and stack that. I find that with these new Zeiss APO lenses do actually work much better than I would have guessed for short stacks. Years ago, when I was first starting out with focus-stacking, I did short stacks because I was lazy, and the results were that I had way too many artifacts in the final images.

But with, as I have mentioned in many articles now, these three new Zeiss APO lenses (135mm, 55mm, 85mm), this short-stack technique seems to work out very well indeed. And I don’t even stack them in the ordinary way. Yes, I use Zerene Stacker with short stacks, but when retouching I have a different approach. Ordinarily, I retouch artifacts only, but with the short-stack approach I tend to just paint in from each of the layers just the main part that layer has in perfect focus, kind of in a whole-cloth sort of way. Most of us used to this in Photoshop. I do have to pay attention to where these layers overlap, but I have been surprised how successful that has been.

Here is a little tableau I have put together. I will have to show a larger view at another time, but I am focusing on the two-dollar bill, but have included some burlap (pleated) so that it rises up and we can see how much depth-of-field is available at the higher apertures. Perhaps some of you reading this will have suggestions for what kinds of objects I could additionally include.

These shots are not about color, but about resolution, diffraction, and depth-of-field. I notice that I can get away with f/11 (see the copper tacks), but with f/16 it is more iffy (but often still usable) for close-up, but not for macro. Lately my internal mantra seems to be “I always seem to go for high resolution,” but am interested more in acuity (micro-contrast) in post. And I only do all of this with APO lenses, for the most part.

Your thoughts? Are these kind of images useful to anyone by myself?
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JohnBrew

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Re: The Zeiss 135mm API, f/2 and Depth-of-Field
« Reply #1 on: March 24, 2015, 07:45:17 am »

Thank you, Michael. Your experience with the 135 @ f16 replicates mine with the 55. The only difference is I do landscape, but very little close-up.

kers

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Re: The Zeiss 135mm API, f/2 and Depth-of-Field
« Reply #2 on: March 24, 2015, 08:49:04 am »

This Zeiss looks terrific wide open !
& a perfect flat field- beautiful
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Jack Hogan

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Re: The Zeiss 135mm API, f/2 and Depth-of-Field
« Reply #3 on: March 24, 2015, 10:30:15 am »

The Zeiss 135mm is sharp wide-open, so I don’t have to add a couple of f/stops to achieve better resolution.
...
With traditional one-shot photos, when I am not stacking, I find that from the Zeiss 135 APO I can get usable resolution and acutance all the way to up to something like f/13, which is a long way. Yes, by then I am recording diffraction that bothers me (and way before that), but I often can get by with it. If I don’t need peak sharpness for the particular subject, I can shoot at f/16 and inject some little bit of needed clarity or contrast in post. Beyond f/16 I am getting too much diffraction and image-degradation to venture there.
...
Your thoughts? Are these kind of images useful to anyone by myself?

Hi Michael,

I have enjoyed your recent post, great images.

As already mentioned, in order to give you meaningful feedback one would need to better understand what it is that you mean when you speak of micro-contrast.  Acuity as a term does not help because it includes psychovisual processing by the brain in its definition.  We can make acuity whatever we want with just a little rough sharpening but the result certainly wouldn't look pretty to the trained eye.  So I will assume that by micro-contrast you mean 'sharpness' in some part of the actual physical linear spatial resolution information captured by your raw files.

If so, the first thing to keep in mind is that it is very difficult to determine peak sharpness eyeballing the subject through the viewfinder.  In fact it is difficult to determine it by pixel peeping images at 100%.  The better way is to focus peak and measure it.  Lenstip.com is a site that does just that and they happen to have measured the Zeiss Apo Sonnar T*135f/2 on a D3X, which I believe you own.  Unfortunately they test lenses at around 30X focal length as I recall, which may not be the way you use them, so take the following camera dependent comments with a grain of salt.

Take a look at their Apo T*135 measurements: f/4 results in best middle-of-the-road captured 'sharpness', about 10% better than what can be accomplished wide open (or again at around f/7).  Although it is very difficult to see a difference of 5%, 10% would be definitely noticeable.  By f/11 you are more than 20% off the peak; and by f/16 almost 1/3 off the peak, giving up a ton of 'micro-contrast'.

So leaving DOF considerations aside for a moment, if you were satisfied with your kit's performance at f/2 you may want to try it at f/4 or even f/7 to see how it does there with your kind of setup.  If f/7 indeed proved as 'sharp' as f/2, it would most likely be preferable because it would sharpen up better in post, given the fewer aberrations and the better behaved PSF due in larger part to diffraction at that aperture.

Best,
Jack

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Michael Erlewine

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Re: The Zeiss 135mm API, f/2 and Depth-of-Field
« Reply #4 on: March 24, 2015, 11:23:08 am »

Thanks for commenting. I am not an expert in this testing, obviously. Here is what I understand, so please point out what I am missing.

What passes for “Sharpness” in common reference is not any kind of standard. On the contrary, it is made of several factors, perhaps more. There is sheer resolution, which the various test charts do a good job of defining. Then, as you mention, there is “acutance,” which has to do with the sharpening of edges, and this is what is sometimes called “micro-contrast.” Now, this term micro-contrast and by association acuity has, as you put it, “psychovisual processing,” with seems to be somewhat of a subjective term, personal to some degree. But so are we, subjective and personal beyond measuring.

So, there is resolution and acutance. Lastly, and something I am very interested in, is the degree of correction, what is called “apochromatic,” another term that has no standards such as resolution has. The above is what I understand, right or wrong.

We are used to assuming that peak “sharpness” is a couple stops up from wide-open, and this seems to be true for the new Zeiss APOs, but very much less than for most lenses. Then there are many industrial lenses (enlarge, scanners, etc.) that are best (and only best) wide open. Even though they have variable apertures, anything but wide open is degraded.

What I am trying to do is come up with a simple rule of thumb (I may have to write it down) for each lens that works for my close-up photography. I find that once I am satisfied that a lens is “sharp” enough and corrected well enough, then I set those considerations to the side and see what in general limits I can use the lens and not run into the kind of troubles we have with lenses in general.

In my case, after the technical stuff, I begin to consider composition and all of the more personal (and artistic) considerations. I find that I can often shoot f/16 (one-shot) with the Zeiss Otus 55mm and the images looks fine, at least good enough to bring out the “art” in the shot. I am not at all interested in forensics or copy-lenses, per se. All this technical stuff is just the base for artistic improvisation. That is why I do it, aside from (my wife would testify to this) that I just like fine lenses.

My particular take on close-up photography are shots like this, taken with one of the high-end Nikons bodies and the industrial CRT-Nikkor-O, a sharp, but not well-corrected lens that has quirks that I find creative. 
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Jack Hogan

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Re: The Zeiss 135mm API, f/2 and Depth-of-Field
« Reply #5 on: March 24, 2015, 02:21:12 pm »

Thanks for commenting. I am not an expert in this testing, obviously. Here is what I understand, so please point out what I am missing.

What passes for “Sharpness” in common reference is not any kind of standard. On the contrary, it is made of several factors, perhaps more. There is sheer resolution, which the various test charts do a good job of defining. Then, as you mention, there is “acutance,” which has to do with the sharpening of edges, and this is what is sometimes called “micro-contrast.” Now, this term micro-contrast and by association acuity has, as you put it, “psychovisual processing,” with seems to be somewhat of a subjective term, personal to some degree. But so are we, subjective and personal beyond measuring.

Not missing anything Michael.  I now understand that by micro-contrast you mean sharp edges, which relate to the highest spatial frequencies.

It may be helpful to separate the objective from the subjective in your endeavors, aka the hardware from the software.  The idea is to capture the best spatial resolution information possible in the raw data (and measure that) comfortable in the knowledge that with better objective ‘sharpness’ information to start with we are going to achieve better final results after subjective processing.

Alternatively you could start from pleasingly (to you) sharp processed images and work backwards, but that would give you much more arbitrary indications.

So, there is resolution and acutance. Lastly, and something I am very interested in, is the degree of correction, what is called “apochromatic,” another term that has no standards such as resolution has. The above is what I understand, right or wrong.

Sounds pretty good.  Another way to look at chromatic and spherical aberrations is that part of a scene's detail is out of focus.  This may result in color fringes and reduced contrast.  Measurements in the raw data will pick those up if present, resulting in lower performance than from an apochromat.

What I am trying to do is come up with a simple rule of thumb (I may have to write it down) for each lens that works for my close-up photography. I find that once I am satisfied that a lens is “sharp” enough and corrected well enough, then I set those considerations to the side and see what in general limits I can use the lens and not run into the kind of troubles we have with lenses in general.

The question is, how do you define 'sharp enough'?  Say it's at least a contrast of 30% at 60 lp/mm on the sensor.  You could measure contrast curves for every camera/lens combination of interest at various apertures and use that information to determine your ideal working range.

Lenstip.com did it for 50% contrast loss in the links above and the threshold there could have been, say, 45 lp/mm.  That would have suggested that you use the ApoT*135 between f/2 and f/7, so maybe that's too stringent a criterion.  Maybe it should be at 38 lp/mm, which would just include f/11.  You see where I am going with this.  You just need to customize the metric for your intended uses.

My particular take on close-up photography are shots like this, taken with one of the high-end Nikons bodies and the industrial CRT-Nikkor-O, a sharp, but not well-corrected lens that has quirks that I find creative. 

Pretty!

Jack
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ErikKaffehr

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Re: The Zeiss 135mm API, f/2 and Depth-of-Field
« Reply #6 on: March 24, 2015, 02:54:54 pm »

Hi Jack,

Something that is often stated that some lenses are more tolerant of diffraction than others. The same has been said about multishot, which achieves higher resolution by moving the sensor half a pixel pitch.

I have not really seen any good explanation. My impression is that most lenses are pretty comparable when stopped down to some medium aperture, say f/8. All of my lenses peaked between 1/5.6 and 1/8. I have a busload of lenses, but they are mostly "middle class".

Axial chroma, that I think Michael mentions several times, is a major issue with older lenses, and also on newer ones at large apertures.

Now I plan on getting a 50 MP camera from Sony when and if it may arrive and I am looking for a nice short telephoto without axial chroma at full aperture, so those Zeiss lenses seem quite attractive.

Best regards
Erik


Not missing anything Michael.  I now understand that by micro-contrast you mean sharp edges, which relate to the highest spatial frequencies.

It may be helpful to separate the objective from the subjective in your endeavors, aka the hardware from the software.  The idea is to capture the best spatial resolution information possible in the raw data (and measure that) comfortable in the knowledge that with better objective ‘sharpness’ information to start with we are going to achieve better final results after subjective processing.

Alternatively you could start from pleasingly (to you) sharp processed images and work backwards, but that would give you much more arbitrary indications.

Sounds pretty good.  Another way to look at chromatic and spherical aberrations is that part of a scene's detail is out of focus.  This may result in color fringes and reduced contrast.  Measurements in the raw data will pick those up if present, resulting in lower performance than from an apochromat.

The question is, how do you define 'sharp enough'?  Say it's at least a contrast of 30% at 60 lp/mm on the sensor.  You could measure contrast curves for every camera/lens combination of interest at various apertures and use that information to determine your ideal working range.

Lenstip.com did it for 50% contrast loss in the links above and the threshold there could have been, say, 45 lp/mm.  That would have suggested that you use the ApoT*135 between f/2 and f/7, so maybe that's too stringent a criterion.  Maybe it should be at 38 lp/mm, which would just include f/11.  You see where I am going with this.  You just need to customize the metric for your intended uses.

Pretty!

Jack
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Michael Erlewine

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Re: The Zeiss 135mm API, f/2 and Depth-of-Field
« Reply #7 on: March 24, 2015, 04:02:36 pm »

Some comments to the last two posts.

As for defining “sharp enough,” that means sharp enough for my purposes. There are no set standards I am aware of, except for resolution. With APO lenses, we can ask for correction for Red, Green, Blue (and all other colors), and some, like the El Nikkor APO 105mm enlarger lens that is corrected in the near UV and Near IR spectrum.  

Lateral chroma is easier to fix in post than the axial variety.

Back to my original comments.

I have looked at about 4 score of lenses for close-up and macro work. Only with the advent of the new Zeiss APOs have I had any wiggle-room to experiment with not-stacking at all, due to their apparent (to me at least) high level of correction. These lenses open doors for me.

I am appreciative of those of you who are also experimenting with the new Zeiss APO. Please keep sharing what you are finding, especially any folks doing close-up work.
« Last Edit: March 25, 2015, 02:57:20 am by Michael Erlewine »
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Jack Hogan

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Re: The Zeiss 135mm API, f/2 and Depth-of-Field
« Reply #8 on: March 24, 2015, 05:50:09 pm »

Axial chroma is easier to fix in post than the lateral variety.

 ;)
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Jack Hogan

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Re: The Zeiss 135mm API, f/2 and Depth-of-Field
« Reply #9 on: March 24, 2015, 05:56:53 pm »

Something that is often stated that some lenses are more tolerant of diffraction than others. The same has been said about multishot, which achieves higher resolution by moving the sensor half a pixel pitch.
I have not really seen any good explanation.

There are none ;) , leaving multiscan/oversampling for a different discussion.  Perhaps the more 'tolerant' lenses are simply those where diffraction, which is relatively easy to partly correct, dominates.

Axial chroma, that I think Michael mentions several times, is a major issue with older lenses, and also on newer ones at large apertures.

Hence their lower MTF values.

Cheers,
Jack
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Bart_van_der_Wolf

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Re: The Zeiss 135mm API, f/2 and Depth-of-Field
« Reply #10 on: March 24, 2015, 07:56:00 pm »

However, what I really want to know is about what kind of curve the particular lens creates from its widest to its narrowest aperture and how does that curve affect my particular work. That’s the curve I actually use. In other words, is it “sharp” wide-open or does that sharpness start a couple of stops later, and how long is that sharpness maintained? What kind of curve do we have, sharp or gentle?

Hi Michael,

It's a gentle/smooth curve, with usually improving resolution from wide open towards one to two stops from wide open, and then it gets progressively worse due to diffraction as one stops down further. See attached chart for my EF 100mm f/2.8L Macro IS. The metric I used is the Blur radius, and thus also the Sharpening radius that's required for Capture sharpening.

The blur caused by defocus, or Depth of Field, is somewhat similar, but obviously different for each aperture, and for the focus distance. The quality of defocus blur (AKA Bokeh) also depends on the lens corrections, and usually differs between front defocus and rear defocus. I've also attached a chart of that for a different lens at its optimal aperture.

Cheers,
Bart
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ErikKaffehr

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Re: The Zeiss 135mm API, f/2 and Depth-of-Field
« Reply #11 on: March 25, 2015, 02:14:42 am »

Hi Jack,

I thought the main aberration reducing sharpness in the focusing plane on fast lenses used to be spherical aberration. I don't really know how axial chroma affects resolution but it gives a very bad bokeh, even with most modern lenses and I happen to be sensitive for that.

The colour bokeh and my inability to achieve exact focus made me loose interest in large aperture work, but now we have a few lenses with very good correction of all aberrations, including axial chroma, mostly due to new optical glass but also by going for complex construction. Then new Zeiss lenses are example of this.

My Minolta 80-200/2.8 APO lens is pretty sharp at 80mm but suffers from a lot of axial chroma. At longer lengths it also has lateral chroma but that handled well by most raw converters, and is therefore not a great problem normally.


The lens is very sharp at 80mm when stopped down to f/8. At 200 mm the tangential and sagittal lines split, and this is probably caused by lateral chromatic aberration.

There is a definition of apochromatic correction, the lens would be corrected for three wave lengths, but in practice it may mean that secondary spectral aberrations are kept low, or just a marketing term.

Best regards
Erik


There are none ;) , leaving multiscan/oversampling for a different discussion.  Perhaps the more 'tolerant' lenses are simply those where diffraction, which is relatively easy to partly correct, dominates.

Hence their lower MTF values.

Cheers,
Jack

« Last Edit: March 25, 2015, 02:16:27 am by ErikKaffehr »
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Michael Erlewine

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Re: The Zeiss 135mm API, f/2 and Depth-of-Field
« Reply #12 on: March 25, 2015, 03:05:08 am »

I am looking (hoping) that the next great lens in the Zeiss Otus line will be a highly-corrected wide-angle lens, somewhere around 21mm-24mm or so. This would be a very difficult lens to produce I am told, but one that I very much could use.

Of course, I have written to the Zeiss lens designers a number of times asking for a very highly-corrected macro lens in the Otus line, but have been told that they would have to sell 10,000 of them to make any money. Perhaps the success of the Otus line will change their view. If I have an Otus wide-angle and macro lens, that is all I need. I don’t do much telephoto photo work. I could sell off scores of lenses sitting around here getting no use.

Since I that the tree Zeiss APOs, they (and the Voigtlander 125mm f/2/5 APO-Lanthar) are all I use, except for some lenses for family portraits.
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Jack Hogan

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Re: The Zeiss 135mm API, f/2 and Depth-of-Field
« Reply #13 on: March 25, 2015, 03:45:01 am »

Hi Jack,

I thought the main aberration reducing sharpness in the focusing plane on fast lenses used to be spherical aberration. I don't really know how axial chroma affects resolution but it gives a very bad bokeh, even with most modern lenses and I happen to be sensitive for that.

The colour bokeh and my inability to achieve exact focus made me loose interest in large aperture work, but now we have a few lenses with very good correction of all aberrations, including axial chroma, mostly due to new optical glass but also by going for complex construction. Then new Zeiss lenses are example of this.

My Minolta 80-200/2.8 APO lens is pretty sharp at 80mm but suffers from a lot of axial chroma. At longer lengths it also has lateral chroma but that handled well by most raw converters, and is therefore not a great problem normally.  The lens is very sharp at 80mm when stopped down to f/8. At 200 mm the tangential and sagittal lines split, and this is probably caused by lateral chromatic aberration.

There is a definition of apochromatic correction, the lens would be corrected for three wave lengths, but in practice it may mean that secondary spectral aberrations are kept low, or just a marketing term.

Best regards
Erik

Excellent, thank you Erik.
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Re: The Zeiss 135mm API, f/2 and Depth-of-Field
« Reply #14 on: March 25, 2015, 03:57:08 am »

It's a gentle/smooth curve, with usually improving resolution from wide open towards one to two stops from wide open, and then it gets progressively worse due to diffraction as one stops down further. See attached chart for my EF 100mm f/2.8L Macro IS. The metric I used is the Blur radius, and thus also the Sharpening radius that's required for Capture sharpening.

Nice chart, Bart.  May I ask how you determined the blur radius readings?  And did you do it off a raw single channel or demosaiced data?

The blur caused by defocus, or Depth of Field, is somewhat similar, but obviously different for each aperture, and for the focus distance.

Right.  The main difference in my mind being that in theory one cannot undo defocus (= also axial spherical and chromatic aberrations in this context) in post while, always in theory, one can undo diffraction.  Hence if one does not need the shallower DOF one would most likely be better off shooting the D3X+ApoT*135 at around f/7 and your 1DsIII+EF100 at f/8 instead of wide open: same linear spatial resolution, fewer aberrations, most likely 'sharper' result once properly rendered.

Jack
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Re: The Zeiss 135mm API, f/2 and Depth-of-Field
« Reply #15 on: March 25, 2015, 07:27:39 am »

There is a definition of apochromatic correction, the lens would be corrected for three wave lengths, but in practice it may mean that secondary spectral aberrations are kept low, or just a marketing term.

Quite true. The usual definition of apochromatic is that correction of longitudinal chromatic aberration is performed for three colors and spherical aberration is corrected for two colors, as discussed in this Zeiss article for color correction.

However, the apochromat designation is often used for lenses that do not meet this designation, but merely keep secondary color "low", and the meaning of "low" is not defined.

The Zeiss article states, "In most cases, the third zero is not required in practice, but it is sufficient to reduce the secondary spectrum to meet the respective requirements. If this is successful, such a lens could be termed 'Apo lens'"

Sigma uses the Apo designation for many relatively inexpensive lenses, and I think this is mainly a marketing ploy. Acceptably low secondary color is subjective. Nikon uses what they call ED glass to help control chromatic aberration, but they do not designate these lenses as Apo.

Cheers,

Bill
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Re: The Zeiss 135mm API, f/2 and Depth-of-Field
« Reply #16 on: March 25, 2015, 10:33:39 am »

On an artistic note, I really like the blur and colors in Michael's plant (name of which escapes me) with the water drop a few posts above.
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Re: The Zeiss 135mm API, f/2 and Depth-of-Field
« Reply #17 on: March 25, 2015, 10:45:40 am »

Yes!


On an artistic note, I really like the blur and colors in Michael's plant (name of which escapes me) with the water drop a few posts above.
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Erik Kaffehr
 

Michael Erlewine

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Re: The Zeiss 135mm API, f/2 and Depth-of-Field
« Reply #18 on: March 25, 2015, 11:12:26 am »

It is just a standard Calla Lily. Here is another taken with the same lens, the industrial CRT Nikkor-O.
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MichaelErlewine.smugmug.com. Founder MacroStop.com, MichaelErlewine.com, YouTube.com/user/merlewine

Larry451

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Re: The Zeiss 135mm API, f/2 and Depth-of-Field
« Reply #19 on: March 25, 2015, 02:43:19 pm »

your second lily shot is beautiful
it might even qualify for Michael's erotica

regards
Larry.
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