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Archive 2012The new 25mm f2 Distagon ZF
p.25 #1The new 25mm f2 Distagon ZF
Samuli Vahonen wrote:
Actually I hoped the cast was due to different lightning conditions. I'm on market for ZE21 now so I\m suprised how cold D21 is. A new Z version of the lens is as cold as Contax ver, isn't it? If you know...21ZE and 100ZE images are colder than rest of the ZE, specially "simple" lenses Planar 50 & 85. You will notice it ONLY if you shoot exactly same subject with exactly same settings. Otherwise you can equalize the coldness with using 50-75K warmer WB in RAW processing. (Disclaimer: based on experience, not measurements)
Interesting. I believe that in a comparison between the D21 and the Nikkor G 24/1.4 from Wayne, the D21 really looked a LOT warmer. I guess it's all quite relative.
AlexDROP wrote
Toothwalker wrote
My D21/2.8 is just cold, something that I already noticed in the film days.Interesting. I believe that in a comparison between the D21 and the Nikkor G 24/1.4 from Wayne, the D21 really looked a LOT warmer. I guess it's all quite relative.
Apr 07, 2012 at 05:17 AM
p.25 #2The new 25mm f2 Distagon ZF
AlexDROP wrote:
Actually I hoped the cast was due to different lightning conditions. I'm on market for ZE21 now so I\m suprised how cold D21 is. A new Z version of the lens is as cold as Contax ver, isn't it? If you know...
I don't know, but one thing that is easy to adjust in the digital lightroom is the color balance.
In the past I owned several copies of some Contax lenses, and in three cases there were clear color differences between two copies of 'the same' lens. In all likelihood the same will happen to the ZE/ZF line, as lenses age and incremental improvements to coatings are being applied.
Toothwalker wrote
My D21/2.8 is just cold, something that I already noticed in the film days.I don't know, but one thing that is easy to adjust in the digital lightroom is the color balance.
In the past I owned several copies of some Contax lenses, and in three cases there were clear color differences between two copies of 'the same' lens. In all likelihood the same will happen to the ZE/ZF line, as lenses age and incremental improvements to coatings are being applied.
Apr 10, 2012 at 01:56 PM
p.25 #3The new 25mm f2 Distagon ZF
wayne seltzer wrote:
Ok, I understand you like the 25/2's excellent CA correction.
I forgot to add the corners are worse at wider apertures than the f8 ones.
Also, it will be even more noticeable on higher MP cameras like D800.
In my earlier posted midday landscape comparison shots I liked the warmer ZE 21 shots over the 25/2 which I found to have a more bluish cast on the grey grasses.
Maybe you could shoot a couple of color chart comparison shots with same light?
BTW, thanks for all your effort for the above test shots.
I have no color charts, but may find something similar.
Since the transition from sharp to blurred is rather abrupt, a camera like the D800 will not reveal much more blur. However, it may reveal, hopefully, how good it is in the central region.
The chart below shows the performance of two realizations of a given lens that result in the same price tag. It is hypothetical and simple, but not unrealistic. On an APS-size sensor, the red lens is a winner. On a full-frame sensor with a low resolution, blue might be the best choice. On a full-frame sensor with high resolution, the situation is less clear. Do you want to profit from the superior performance of the red lens over a large part of the frame, or do you want to avoid blurry corners? That is a matter of personal preference.
http://toothwalker.org/temp/fm/perf.jpg
Ok, I understand you like the 25/2's excellent CA correction.
I forgot to add the corners are worse at wider apertures than the f8 ones.
Also, it will be even more noticeable on higher MP cameras like D800.
In my earlier posted midday landscape comparison shots I liked the warmer ZE 21 shots over the 25/2 which I found to have a more bluish cast on the grey grasses.
Maybe you could shoot a couple of color chart comparison shots with same light?
BTW, thanks for all your effort for the above test shots.
I have no color charts, but may find something similar.
Since the transition from sharp to blurred is rather abrupt, a camera like the D800 will not reveal much more blur. However, it may reveal, hopefully, how good it is in the central region.
The chart below shows the performance of two realizations of a given lens that result in the same price tag. It is hypothetical and simple, but not unrealistic. On an APS-size sensor, the red lens is a winner. On a full-frame sensor with a low resolution, blue might be the best choice. On a full-frame sensor with high resolution, the situation is less clear. Do you want to profit from the superior performance of the red lens over a large part of the frame, or do you want to avoid blurry corners? That is a matter of personal preference.
http://toothwalker.org/temp/fm/perf.jpg
Apr 10, 2012 at 02:16 PM
p.25 #4The new 25mm f2 Distagon ZF
AhamB wrote:
Actually I hoped the cast was due to different lightning conditions. I'm on market for ZE21 now so I\m suprised how cold D21 is. A new Z version of the lens is as cold as Contax ver, isn't it? If you know...21ZE and 100ZE images are colder than rest of the ZE, specially "simple" lenses Planar 50 & 85. You will notice it ONLY if you shoot exactly same subject with exactly same settings. Otherwise you can equalize the coldness with using 50-75K warmer WB in RAW processing. (Disclaimer: based on experience, not measurements)Interesting. I believe that in a comparison between the D21 and the Nikkor G 24/1.4 from Wayne, the D21 really looked a LOT warmer. I guess it's all quite relative.
Yes the 21 is much warmer than the Nikon 24/1.4G, I've compared them.
Samuli Vahonen wrote
AlexDROP wrote
Toothwalker wrote
My D21/2.8 is just cold, something that I already noticed in the film days.Yes the 21 is much warmer than the Nikon 24/1.4G, I've compared them.
Apr 10, 2012 at 04:49 PM
p.25 #5The new 25mm f2 Distagon ZF
Toothwalker wrote:
I forgot to add the corners are worse at wider apertures than the f8 ones.
Also, it will be even more noticeable on higher MP cameras like D800.
In my earlier posted midday landscape comparison shots I liked the warmer ZE 21 shots over the 25/2 which I found to have a more bluish cast on the grey grasses.
Maybe you could shoot a couple of color chart comparison shots with same light?
BTW, thanks for all your effort for the above test shots.I have no color charts, but may find something similar.
Since the transition from sharp to blurred is rather abrupt, a camera like the D800 will not reveal much more blur. However, it may reveal, hopefully, how good it is in the central region.
The chart below shows the performance of two realizations of a given lens that result in the same price tag. It is hypothetical and simple, but not unrealistic. On an APS-size sensor, the red lens is a winner. On a full-frame sensor with a low resolution, blue might be the best choice. On a full-frame sensor with high...Show more →
I see your point. I want the red curve design but designed for a slightly larger image circle.
There is also the curve for the 40lp for the new 15 which takes a big drop in zone b and rebounds back in zone c.
wayne seltzer wrote
Ok, I understand you like the 25/2's excellent CA correction.I forgot to add the corners are worse at wider apertures than the f8 ones.
Also, it will be even more noticeable on higher MP cameras like D800.
In my earlier posted midday landscape comparison shots I liked the warmer ZE 21 shots over the 25/2 which I found to have a more bluish cast on the grey grasses.
Maybe you could shoot a couple of color chart comparison shots with same light?
BTW, thanks for all your effort for the above test shots.
Since the transition from sharp to blurred is rather abrupt, a camera like the D800 will not reveal much more blur. However, it may reveal, hopefully, how good it is in the central region.
The chart below shows the performance of two realizations of a given lens that result in the same price tag. It is hypothetical and simple, but not unrealistic. On an APS-size sensor, the red lens is a winner. On a full-frame sensor with a low resolution, blue might be the best choice. On a full-frame sensor with high...Show more →
I see your point. I want the red curve design but designed for a slightly larger image circle.
There is also the curve for the 40lp for the new 15 which takes a big drop in zone b and rebounds back in zone c.
Apr 10, 2012 at 06:09 PM
p.25 #6The new 25mm f2 Distagon ZF
'There is also the curve for the 40lp for the new 15 which takes a big drop in zone b and rebounds back in zone c.'
Not at f11, Wayne, and that 40 lpmm (tan drops away with increasing IH like some Contax Sonnars, but even so) stays around or above 60% at those unfashionable apertures of f8 and f11, right out into the far corners:
http://diglloyd.com/articles/ZeissZ/ZeissZ-15Distagon-NasseInterview-Performance.html
My Contax 21mm seems very well-balanced in terms of colour temp. Maybe the coatings wore out like cheap car window tint, lol.
Not at f11, Wayne, and that 40 lpmm (tan drops away with increasing IH like some Contax Sonnars, but even so) stays around or above 60% at those unfashionable apertures of f8 and f11, right out into the far corners:
http://diglloyd.com/articles/ZeissZ/ZeissZ-15Distagon-NasseInterview-Performance.html
My Contax 21mm seems very well-balanced in terms of colour temp. Maybe the coatings wore out like cheap car window tint, lol.
Apr 10, 2012 at 09:08 PM
p.25 #8The new 25mm f2 Distagon ZF
Toothwalker's comparison between the ZE 25 and the C/Y 21/2.8 is puzzling. Assuming that the MTF for the C/Y is the one seen on page 6 of this paper from Zeiss, it should be no better than the ZE25 anywhere but in the corners. Looking at the test shots, though, the C/Y looks anywhere from slightly to substantially sharper everywhere but the central 1/3 of the frame.
May 13, 2012 at 09:46 AM
p.25 #9The new 25mm f2 Distagon ZF
Dan1 wrote:
Toothwalker's comparison between the ZE 25 and the C/Y 21/2.8 is puzzling. Assuming that the MTF for the C/Y is the one seen on page 6 of this paper from Zeiss, it should be no better than the ZE25 anywhere but in the corners. Looking at the test shots, though, the C/Y looks anywhere from slightly to substantially sharper everywhere but the central 1/3 of the frame.
I wonder how you interpret these MTF charts. For instance, at f/4 and u' = 10 mm, the Y/C should be noticeably better in the rendering of fine detail.
On the other hand it is uncertain how well my focusing with live view matches the Zeiss MTF focus criterion, and somewhere in another thread it was concluded that there exist at least three different versions of the Y/C D21 MTF charts.
Toothwalker's comparison between the ZE 25 and the C/Y 21/2.8 is puzzling. Assuming that the MTF for the C/Y is the one seen on page 6 of this paper from Zeiss, it should be no better than the ZE25 anywhere but in the corners. Looking at the test shots, though, the C/Y looks anywhere from slightly to substantially sharper everywhere but the central 1/3 of the frame.
I wonder how you interpret these MTF charts. For instance, at f/4 and u' = 10 mm, the Y/C should be noticeably better in the rendering of fine detail.
On the other hand it is uncertain how well my focusing with live view matches the Zeiss MTF focus criterion, and somewhere in another thread it was concluded that there exist at least three different versions of the Y/C D21 MTF charts.
May 15, 2012 at 11:00 AM
p.25 #10The new 25mm f2 Distagon ZF
Toothwalker wrote:
On the other hand it is uncertain how well my focusing with live view matches the Zeiss MTF focus criterion, and somewhere in another thread it was concluded that there exist at least three different versions of the Y/C D21 MTF charts.
Are you suggesting that your 21 could be even better than this chart indicates? I do not have enough experience to be able to extrapolate, quantitatively, from what I see in a test image to chart curves.
On the other hand it is uncertain how well my focusing with live view matches the Zeiss MTF focus criterion, and somewhere in another thread it was concluded that there exist at least three different versions of the Y/C D21 MTF charts.
Are you suggesting that your 21 could be even better than this chart indicates? I do not have enough experience to be able to extrapolate, quantitatively, from what I see in a test image to chart curves.
May 15, 2012 at 12:38 PM
p.25 #11The new 25mm f2 Distagon ZF
Dan1 wrote:
Are you suggesting that your 21 could be even better than this chart indicates? I do not have enough experience to be able to extrapolate, quantitatively, from what I see in a test image to chart curves.
I am just suggesting that my 21 might be different from this chart. Since there are different charts in circulation for the same lens, they can't all be correct.
To appreciate the remark about the focus criterion one only needs to look at the two graphs on page 27 of this document. A small difference in focus can lead to a quite different MTF picture even at f/4.
Toothwalker wrote
On the other hand it is uncertain how well my focusing with live view matches the Zeiss MTF focus criterion, and somewhere in another thread it was concluded that there exist at least three different versions of the Y/C D21 MTF charts.I am just suggesting that my 21 might be different from this chart. Since there are different charts in circulation for the same lens, they can't all be correct.
To appreciate the remark about the focus criterion one only needs to look at the two graphs on page 27 of this document. A small difference in focus can lead to a quite different MTF picture even at f/4.
May 15, 2012 at 02:01 PM
p.25 #12The new 25mm f2 Distagon ZF
Toothwalker wrote:
Are you suggesting that your 21 could be even better than this chart indicates? I do not have enough experience to be able to extrapolate, quantitatively, from what I see in a test image to chart curves.I am just suggesting that my 21 might be different from this chart. Since there are different charts in circulation for the same lens, they can't all be correct.
To appreciate the remark about the focus criterion one only needs to look at the two graphs on page 27 of this document. A small difference in focus can lead to a quite different MTF picture even at f/4.
I see what you mean. I had assumed that all MTF charts were made while focusing for the center of the field. However, since the charts for both lenses in question reach peak contrast values in the center, wouldn't this indicate that they were focusing for there?
Edit: just looked at both charts again and saw that they peak at 5mm image height.
Dan1 wrote
Toothwalker wrote
On the other hand it is uncertain how well my focusing with live view matches the Zeiss MTF focus criterion, and somewhere in another thread it was concluded that there exist at least three different versions of the Y/C D21 MTF charts.To appreciate the remark about the focus criterion one only needs to look at the two graphs on page 27 of this document. A small difference in focus can lead to a quite different MTF picture even at f/4.
I see what you mean. I had assumed that all MTF charts were made while focusing for the center of the field. However, since the charts for both lenses in question reach peak contrast values in the center, wouldn't this indicate that they were focusing for there?
Edit: just looked at both charts again and saw that they peak at 5mm image height.
May 15, 2012 at 03:58 PM
p.25 #13The new 25mm f2 Distagon ZF
Dan1 wrote:
I see what you mean. I had assumed that all MTF charts were made while focusing for the center of the field. However, since the charts for both lenses in question reach peak contrast values in the center, wouldn't this indicate that they were focusing for there?
Edit: just looked at both charts again and saw that they peak at 5mm image height.
Zeiss MTF is optimized for 20 lp/mm, in the image center, and at full aperture. There is no refocusing for reduced apertures, so that peak contrast values may shift away from the center in the presence of residual spherical aberration and field curvature.
I see what you mean. I had assumed that all MTF charts were made while focusing for the center of the field. However, since the charts for both lenses in question reach peak contrast values in the center, wouldn't this indicate that they were focusing for there?
Edit: just looked at both charts again and saw that they peak at 5mm image height.
Zeiss MTF is optimized for 20 lp/mm, in the image center, and at full aperture. There is no refocusing for reduced apertures, so that peak contrast values may shift away from the center in the presence of residual spherical aberration and field curvature.
May 16, 2012 at 09:25 AM
p.25 #14The new 25mm f2 Distagon ZF
Toothwalker wrote:
Zeiss MTF is optimized for 20 lp/mm, in the image center, and at full aperture. There is no refocusing for reduced apertures, so that peak contrast values may shift away from the center in the presence of residual spherical aberration and field curvature.
Is this not, in effect, how you would have focused the lens?
Zeiss MTF is optimized for 20 lp/mm, in the image center, and at full aperture. There is no refocusing for reduced apertures, so that peak contrast values may shift away from the center in the presence of residual spherical aberration and field curvature.
Is this not, in effect, how you would have focused the lens?
May 17, 2012 at 07:14 AM
p.25 #15The new 25mm f2 Distagon ZF
Dan1 wrote:
Is this not, in effect, how you would have focused the lens?
I don't know whether I optimize for 20 lp/mm with live view. I suppose it is close, but even live view is not as accurate as the optical bench.
Toothwalker wrote
Zeiss MTF is optimized for 20 lp/mm, in the image center, and at full aperture. There is no refocusing for reduced apertures, so that peak contrast values may shift away from the center in the presence of residual spherical aberration and field curvature.I don't know whether I optimize for 20 lp/mm with live view. I suppose it is close, but even live view is not as accurate as the optical bench.
May 17, 2012 at 07:32 AM
p.25 #16The new 25mm f2 Distagon ZF
I had assumed that the optimal point for all spatial frequencies would be the same. Can you direct me to an explanation of how this works? I am not questioning your word, but curious.
Getting back to the lens in question: I am considering purchasing this as my primary wide for both infinity and closer work on the D800, so I would appreciate any comments you can offer on its performance relative to other wides that can be had at this price point. If something like the ZF 21 will produce better results then I am not opposed to going that route while also picking up a longer wide to fill the gap in speed and FOV.
Edit: I see from the MTFs and comments other have made that the 25 has lower contrast than the 21 at 40 lp/mm and at the frame edge for apertures below f/5.6. My biggest question is in regards to f/8, where the examples shown have been contradictory to each other.
Getting back to the lens in question: I am considering purchasing this as my primary wide for both infinity and closer work on the D800, so I would appreciate any comments you can offer on its performance relative to other wides that can be had at this price point. If something like the ZF 21 will produce better results then I am not opposed to going that route while also picking up a longer wide to fill the gap in speed and FOV.
Edit: I see from the MTFs and comments other have made that the 25 has lower contrast than the 21 at 40 lp/mm and at the frame edge for apertures below f/5.6. My biggest question is in regards to f/8, where the examples shown have been contradictory to each other.
May 17, 2012 at 09:50 AM
p.25 #17The new 25mm f2 Distagon ZF
Dan1 wrote:
I had assumed that the optimal point for all spatial frequencies would be the same. Can you direct me to an explanation of how this works? I am not questioning your word, but curious.
Take a look at page 24 (and beyond) of the document that I linked to before.
Getting back to the lens in question: I am considering purchasing this as my primary wide for both infinity and closer work on the D800, so I would appreciate any comments you can offer on its performance relative to other wides that can be had at this price point. If something like the ZF 21 will produce better results then I am not opposed to going that route while also picking up a longer wide to fill the gap in speed and FOV.
Edit: I see from the MTFs and comments other have made that the 25 has lower contrast than the...Show more →
I haven't had much shooting time yet with the 25/2, but would not hesitate to use it for any kind of close-focus application. Its implementation of variable air spaces is simply excellent. For landscapes I would pick the 21/2.8 if it happens to be in the bag. If it is not in the bag, I will happily use the 25/2 because the soft extreme corners (even at f/8) don't bother me much.
I had assumed that the optimal point for all spatial frequencies would be the same. Can you direct me to an explanation of how this works? I am not questioning your word, but curious.
Take a look at page 24 (and beyond) of the document that I linked to before.
Getting back to the lens in question: I am considering purchasing this as my primary wide for both infinity and closer work on the D800, so I would appreciate any comments you can offer on its performance relative to other wides that can be had at this price point. If something like the ZF 21 will produce better results then I am not opposed to going that route while also picking up a longer wide to fill the gap in speed and FOV.
Edit: I see from the MTFs and comments other have made that the 25 has lower contrast than the...Show more →
I haven't had much shooting time yet with the 25/2, but would not hesitate to use it for any kind of close-focus application. Its implementation of variable air spaces is simply excellent. For landscapes I would pick the 21/2.8 if it happens to be in the bag. If it is not in the bag, I will happily use the 25/2 because the soft extreme corners (even at f/8) don't bother me much.
May 17, 2012 at 05:11 PM
p.25 #18The new 25mm f2 Distagon ZF
Thank you. I have seen in G. Pierre's cathedral shots how very far out into the corner the sharpness begins to degrade at f/8; not a problem in my opinion. I see this lens in my future.
May 17, 2012 at 07:02 PM