2/35mm asph corner sharpness?

[batmobile]

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If the first one is the cron asph then there is a likely a problem with that lens. It should be much sharper than that at middle apertures and not have the same rapid drop off in resolution in the corner. I have a Summarit-M and it is far better than that at 5.6. The second frame is what most lenses should deliver at 5.6 in the corners and what the ZM Biogon will deliver at 2.8 or so.

[schn€id€r]

Thank you all for your interest you took in this issue; I have to mention that I had the lens checked by Leica, Solms, before I made these pictures, and the technician did not find anything wrong; it was, he said, rather in the middle of tolerances.

 

And here is the solution of my little puzzle:

 

Both pictures were taken with the summicron 35mm asph., both focused at infinity, and both at f-stop 5.6. The only difference was: Picture (the relatively sharp one) has been taken with an orange filter on it (and, of course, a longer exposure time)!

 

This observation led me to the theory that it are the blue wave-lenghts of the light which are responsible for the softness in the corners - when they are blocked by an orange filter, the picture seems sharp.

 

I presented these pictures and findings to Leica, and they confirmed this observation and theory ("correctly identified by the customer"), saying that the downfall in the edges can be derived from the MTFs (which is quite true, just that I did not think that this would be visible in such an obvious way), ending with: "the lens is in order".

 

So all in all, it doesn't seem to be a fault, rather a feature. I'll have to live with it, I think. But I thought the orange-filter-issue might be of some interest to you.

 

Finally, I think I can exclude flatness problems, I really doublechecked this with other lenses and the negatives themselves. And if it was a scanner problem, I would not be able to produce corners such as these:

 

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This has been taken from a picture which can be found here:

 

http://www.l-camera-forum.com/leica-forum/landscape-travel/126312-mountain-river.html#post1335626.

 

So I would like to thank everybody for your interest and contributions, which I really appreciate!

 

Best wishes so far

 

Michael

[batmobile]

wow.... but I am still a bit baffled as I have never seen such a problem with my lenses, including Leica... but then again I always shoot with a yellow unless in poor light or indoors.

[01af]

It's a well-known fact that B/W images taken with a dark-yellow, orange, or light-red filter usually are sharper than without filter. Blocking blue (and part of green) helps with chromatic aberrations.

[sbelyaev]

Thank you all for your interest you took in this issue; I have to mention that I had the lens checked by Leica, Solms, before I made these pictures, and the technician did not find anything wrong; it was, he said, rather in the middle of tolerances.

 

And here is the solution of my little puzzle:

 

Both pictures were taken with the summicron 35mm asph., both focused at infinity, and both at f-stop 5.6. The only difference was: Picture (the relatively sharp one) has been taken with an orange filter on it (and, of course, a longer exposure time)!

 

This observation led me to the theory that it are the blue wave-lenghts of the light which are responsible for the softness in the corners - when they are blocked by an orange filter, the picture seems sharp.

 

I presented these pictures and findings to Leica, and they confirmed this observation and theory ("correctly identified by the customer"), saying that the downfall in the edges can be derived from the MTFs (which is quite true, just that I did not think that this would be visible in such an obvious way), ending with: "the lens is in order".

 

So all in all, it doesn't seem to be a fault, rather a feature. I'll have to live with it, I think. But I thought the orange-filter-issue might be of some interest to you.

 

Finally, I think I can exclude flatness problems, I really doublechecked this with other lenses and the negatives themselves. And if it was a scanner problem, I would not be able to produce corners such as these:

 

[ATTACH]203639[/ATTACH]

 

This has been taken from a picture which can be found here:

 

http://www.l-camera-forum.com/leica-forum/landscape-travel/126312-mountain-river.html#post1335626.

 

So I would like to thank everybody for your interest and contributions, which I really appreciate!

 

Best wishes so far

 

Michael

 

I had somewhat similar experience with summicron 35/2 asph. That is the reason why I prefer prior generation of that lens or summarit 35/2.5.

[Bruce Robbins]

Why not try Zeiss?

[Guest Ornello]

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My impression is that there is something amiss. The lens should be looked at by a service technician.

[Guest Ornello]

Thank you all for your interest you took in this issue; I have to mention that I had the lens checked by Leica, Solms, before I made these pictures, and the technician did not find anything wrong; it was, he said, rather in the middle of tolerances.

 

And here is the solution of my little puzzle:

 

Both pictures were taken with the summicron 35mm asph., both focused at infinity, and both at f-stop 5.6. The only difference was: Picture (the relatively sharp one) has been taken with an orange filter on it (and, of course, a longer exposure time)!

 

This observation led me to the theory that it are the blue wave-lenghts of the light which are responsible for the softness in the corners - when they are blocked by an orange filter, the picture seems sharp.

 

I presented these pictures and findings to Leica, and they confirmed this observation and theory ("correctly identified by the customer"), saying that the downfall in the edges can be derived from the MTFs (which is quite true, just that I did not think that this would be visible in such an obvious way), ending with: "the lens is in order".

 

So all in all, it doesn't seem to be a fault, rather a feature. I'll have to live with it, I think. But I thought the orange-filter-issue might be of some interest to you.

 

Finally, I think I can exclude flatness problems, I really doublechecked this with other lenses and the negatives themselves. And if it was a scanner problem, I would not be able to produce corners such as these:

 

[ATTACH]203639[/ATTACH]

 

This has been taken from a picture which can be found here:

 

http://www.l-camera-forum.com/leica-forum/landscape-travel/126312-mountain-river.html#post1335626.

 

So I would like to thank everybody for your interest and contributions, which I really appreciate!

 

Best wishes so far

 

Michael

 

I find that hard to believe. It seems that there is something wrong with the lens.

[andybarton]

This is a TWO year old thread. I'm sure it's been resolved by now.

[Guest Ornello]

This is a TWO year old thread. I'm sure it's been resolved by now.

 

Oh? well some one else revived it, not me!

[Bruce Robbins]

You would certainly hope that Leitz would have fixed a defective lens by now but what if the OP is still struggling with an unsharp corner? That's a hell of an affliction to leave anyone with, especially since he probably paid a lot of money for the lens and has a right to expect better.

[250swb]

You would certainly hope that Leitz would have fixed a defective lens by now but what if the OP is still struggling with an unsharp corner? That's a hell of an affliction to leave anyone with, especially since he probably paid a lot of money for the lens and has a right to expect better.

 

Nobody knows the OP's workflow, sharpening strategy, nor anything at all about the images other than the lens is being blamed. And who are 'Leitz'?

 

Steve

[LotharZhou]

Exactly, one of the reason I got rid of my cron35 and bought the ZM Biogon instead,

extreme sharp from corner to corner.

 

Why not try Zeiss?

[Guest Ornello]

Exactly, one of the reason I got rid of my cron35 and bought the ZM Biogon instead,

extreme sharp from corner to corner.

 

 

Here is a test by Ken Rockwell (for what that's worth) of several generations of 35mm Summicrons:

 

LEICA 35mm SUMMICRON Sharpness Comparison

 

The results shown here (on this thread) do not agree with his test results. Even though I regard Rockwell as a bit of a light-weight, I do think the tests appear to be sound.

 

I suggest a tech look at it, after a more suitable test is performed.

[LeicaPassion]

Years ago LFI published an article on lens tests. It stated that a lens cannot be fully evaluated by one or two tests, for instance, shooting a test target to determine sharpness. About 35 ( if my memory is correct) different aspects need to examined under controlled conditions.

[Guest Ornello]

Years ago LFI published an article on lens tests. It stated that a lens cannot be fully evaluated by one or two tests, for instance, shooting a test target to determine sharpness. About 35 ( if my memory is correct) different aspects need to examined under controlled conditions.

 

I agree, but Ken Rockwell's tests are of four 35mm Summicrons compared against each other under the same conditions and at various apertures. The photos in this thread do not seem consistent with a 35mm Summicron ASPH lens in good working order. Ken's tests show progressively better corner performance with each generation of the 35mm Summicron, which confirms that Leica was actually steadily improving the design at each generation (the first, 8-element lens though, is somewhat of an anomaly, but its overall contrast was lower). The corner performance of the 35mm Summicron ASPH in Ken's tests looks very good to me, nothing like what the poster shows in his B&W images.

[Bruce Robbins]

Nobody knows the OP's workflow, sharpening strategy, nor anything at all about the images other than the lens is being blamed. And who are 'Leitz'?

 

Steve

 

I thought it was self-evident from what the OP said and the examples he posted that it was the lens that was at fault. The last time I saw that sort of corner performance from a lens was with a Komura 24-35 zoom. Sorry about the Leitz reference. Old habits die hard. I'm off to load up my camera with some 100 ASA film...