I have linked to a PDF document that outlines information in relation to the Schneider-Kreuznach XENOPLAN 1.7/17mm.
Could someone translate the relevant technical aspects with regard to photomacrographic application?
http://www.subtechnique.com/schneider/P ... _17_17.pdf
Just noticed there is also a PDF for the 1.9/25mm
http://www.subtechnique.com/schneider/P ... _19_25.pdf
Craig
Schneider-Kreuznach XENOPLAN 1.7/17mm
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augusthouse
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Schneider-Kreuznach XENOPLAN 1.7/17mm
To use a classic quote from 'Antz' - "I almost know exactly what I'm doing!"
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rjlittlefield
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I assume you're talking about reversing the lens and using it for high magnification. In that case, these specifications are not very relevant.
Note at the top of page 2 that MTF curves are given only for 10, 20, and 30 cycles/mm, over a nominal area of 6.6 x 8.8 mm. The three lines of the page are for different magnifications, with the bottom line corresponding to 0.1X onto the sensor with the lens in its ordinary non-reversed configuration. That line of the page corresponds to 10X if you reverse the lens, but then you also have to interpret the 10, 20, and 30 cycles/mm in terms of the subject, not the sensor. If you're using a 15 x 22 mm sensor, then at 10X, you have a 1.5 x 2.2 mm subject frame, so even 30 cycles/mm is only 66 cycles per subject width! This spatial frequency is much too low to care about. To be very meaningful for this application, the curves would have to quote MTF at much higher numbers. See HERE for further discussion.
It is interesting that the PDF shows central MTF at 30 cycles/mm to be lower at f/4.0 than at either f/1.7 or f/5.6. Why would contrast drop and then rise again as you stop down? One answer may be provided by the note at bottom of page, that the lens was focused for maximum MTF at f/1.7. I speculate that this lens exhibits significant focus shift over the first couple of f/stops, so that f/4.0 represents a point where the test plane has gone slightly out of focus, while f/5.6 has no further focus shift and picks up increased contrast because the larger DOF at f/5.6 then encompasses the test plane.
But none of this matters anyway if you are stacking. All that really counts is the maximum frequency at which MTF drops too low to be useful, and these charts do not extend into that range.
Sorry!
--Rik
Note at the top of page 2 that MTF curves are given only for 10, 20, and 30 cycles/mm, over a nominal area of 6.6 x 8.8 mm. The three lines of the page are for different magnifications, with the bottom line corresponding to 0.1X onto the sensor with the lens in its ordinary non-reversed configuration. That line of the page corresponds to 10X if you reverse the lens, but then you also have to interpret the 10, 20, and 30 cycles/mm in terms of the subject, not the sensor. If you're using a 15 x 22 mm sensor, then at 10X, you have a 1.5 x 2.2 mm subject frame, so even 30 cycles/mm is only 66 cycles per subject width! This spatial frequency is much too low to care about. To be very meaningful for this application, the curves would have to quote MTF at much higher numbers. See HERE for further discussion.
It is interesting that the PDF shows central MTF at 30 cycles/mm to be lower at f/4.0 than at either f/1.7 or f/5.6. Why would contrast drop and then rise again as you stop down? One answer may be provided by the note at bottom of page, that the lens was focused for maximum MTF at f/1.7. I speculate that this lens exhibits significant focus shift over the first couple of f/stops, so that f/4.0 represents a point where the test plane has gone slightly out of focus, while f/5.6 has no further focus shift and picks up increased contrast because the larger DOF at f/5.6 then encompasses the test plane.
But none of this matters anyway if you are stacking. All that really counts is the maximum frequency at which MTF drops too low to be useful, and these charts do not extend into that range.
Sorry!
--Rik
Betty has some images taken with the Schneider Xenoplan 1.9/25mm
HERE on page 2
appears to be an excellent macro lens
HERE on page 2
appears to be an excellent macro lens
NU.
student of entomology
Quote – Holmes on ‘Entomology’
” I suppose you are an entomologist ? “
” Not quite so ambitious as that, sir. I should like to put my eyes on the individual entitled to that name.
No man can be truly called an entomologist,
sir; the subject is too vast for any single human intelligence to grasp.”
Oliver Wendell Holmes, Sr
The Poet at the Breakfast Table.
Nikon camera, lenses and objectives
Olympus microscope and objectives
student of entomology
Quote – Holmes on ‘Entomology’
” I suppose you are an entomologist ? “
” Not quite so ambitious as that, sir. I should like to put my eyes on the individual entitled to that name.
No man can be truly called an entomologist,
sir; the subject is too vast for any single human intelligence to grasp.”
Oliver Wendell Holmes, Sr
The Poet at the Breakfast Table.
Nikon camera, lenses and objectives
Olympus microscope and objectives
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augusthouse
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Regarding the Schneider Xenoplan 1.7/17mm (f1.7 to f16).
Basically, it appears the lens must be reverse mounted otherwise an image cannot be formed on the sensor.
It likes f4; but even @f/4 the resulting image (initial observation) is lacking in qualities that would be present if an appropriate Nikon 10x CF non-infinity corrected (finite) microscope objective or OM Zuiko Macro 20mm had been used instead.
However, the Xenoplan 1.7/17mm does have certain, consistent qualities. There is a dreamy, mysterious aspect to the 'softness' @f/1.7 and f/2.
Working distance is a challenge. Stacking result (initial observation) is the Xenoplan 1.7/17mm did not provide any "larger aperture" advantage over comparable, alternative lenses when used for macro on a bellows.
Aperture opening is square/rectangular.
Focus ring works (adjusts focus) when the lens is reversed.
I reverse-mounted this particular lens using the following step rings: 30.5 (male thread) to 37mm (female thread), then a 37mm (male thread) to 52mm (female thread) which attaches to the 52mm male thread of a Nikon BR2A.
** later note @f/1.7
Here are a couple of single frame images taken using the Xenoplan 1.7/17mm. These were taken with the lens wide open at f/1.7. Bellows extension was 210mm. Nikon D100.
The first image is a crop of a frame from a focus stack sequence. The second image is a separate, uncropped image from the same sequence.
Here is another single image. This one was taken @ f/4. Extension 160mm.
Craig
Basically, it appears the lens must be reverse mounted otherwise an image cannot be formed on the sensor.
It likes f4; but even @f/4 the resulting image (initial observation) is lacking in qualities that would be present if an appropriate Nikon 10x CF non-infinity corrected (finite) microscope objective or OM Zuiko Macro 20mm had been used instead.
However, the Xenoplan 1.7/17mm does have certain, consistent qualities. There is a dreamy, mysterious aspect to the 'softness' @f/1.7 and f/2.
Working distance is a challenge. Stacking result (initial observation) is the Xenoplan 1.7/17mm did not provide any "larger aperture" advantage over comparable, alternative lenses when used for macro on a bellows.
Aperture opening is square/rectangular.
Focus ring works (adjusts focus) when the lens is reversed.
I reverse-mounted this particular lens using the following step rings: 30.5 (male thread) to 37mm (female thread), then a 37mm (male thread) to 52mm (female thread) which attaches to the 52mm male thread of a Nikon BR2A.
** later note @f/1.7
Here are a couple of single frame images taken using the Xenoplan 1.7/17mm. These were taken with the lens wide open at f/1.7. Bellows extension was 210mm. Nikon D100.
The first image is a crop of a frame from a focus stack sequence. The second image is a separate, uncropped image from the same sequence.
Here is another single image. This one was taken @ f/4. Extension 160mm.
Craig
To use a classic quote from 'Antz' - "I almost know exactly what I'm doing!"