All of a sudden... Problem with 21/4 Skopar

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bmoc

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Going through the negs from my last vacation, I notice that those photos taken with the 21/4 Skopar have severe uneven field illumination. I've had this lens for a year or two, and it doesn't show on any other negs. Any explanation? After looking at the first image, I assumed the uneven light was due to the light source; however, shots from several different angles taken within minutes of each other have light falloff in the same place of the frame (right side, more to the top of the frame). Is this something that can be adjusted by a tech?

Thanks,
Barry
 

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very strange. Look at the neg itself - does it look like this? Not the scanner, is it? And also look at the negs to see if you have even focus across a chosen DOF.
 
Definitely on the neg, and only with this lens. Might be a particular aperture--will have to look and see.
 
I was gonna say, looks like a shutter problem, but if only with this lens... Hmmm. Why would a particular aperture setting result in light fall off? Hope someone figures this one out.

My sympathies.

Ted
 
Does this show up on an evenly illuminated surface? 21 is pretty wide and a scene such as the one in the example pic can have a pretty wide range.
I've seen this with my 20mm Nikkor when strong light is coming from the side of the scene.

Peter
 
Yeah, but he said this is happening equally on a number of frames from different angles. .. or did i misread.
 
shutterflower said:
Yeah, but he said this is happening equally on a number of frames from different angles. .. or did i misread.
Click to expand...
You didn't misread.
If it was the shutter, I'd expect the problem to show with other lenses.
It's possible it's some kind of flare in the lens, but that's kinda remote.

Peter
 
This is almost identical to a thread that was started about a week ago:
http://www.rangefinderforum.com/forums/showthread.php?t=22091

Different lens, but the same sort of 'problem'.

My theory last time was polarization and I'm going to suggest the same this time. We've only got one image to go by here, but it does look like polarization to me. Some lenses do have a small natural polarizing effect due to different types of glass and coatings being used. This is often more noticable in wide angle lenses. So you don't need to use a polarizer in order to get the effect, especially in strong light with a clear blue sky, with the Sun at 90 degrees to the camera.

I think a shutter fault is unlikely, the Bessa shutter operates top to bottom rather than across, therefore a shutter fault would appear as a horizontal band rather than on the left or right. Unless of course, you're using some other camera with a shutter that operates left to right.

It could be an aperture fault, this is very easy to check... Just operate the aperture ring through all apertures and look for any odd movements in the blades.

A stray finger may also be a possibility. Flare is another, although this doesn't look very 'flare like' to me. The LH-1 lens hood would reduce the chances of both of these happening.
 
My ultra-wides tend to do that especially outdoors with blue skys. I'll guess that the right side of the structure is close to 90% from the sun, which is naturally the bluest part of the sky. That plus the vignetting that occurs with most ultra-wides will cause the corner to be even more dark. An ultra-wide like a 12, 15 or 20 + polarizer can turn part of the sky almost dark blue.
 
I have seen this happen when using a 24mm on my SLRs and it is worse if you use a polarizer. I think I would agree with Kin Lau about the causes. It is typical of a very/ultra wide lens with alot of sky in the photo from my experience.

Nikon Bob
 
Thanks for all your replies. I was using a Canon VT with a left-to-right shutter that was just adjusted--and yes, only happening with this lens and only on the right side toward the top of the frame (no matter the angle of the film plane relative to the sun). Using the small hood that came with the lens and no filter. Aperture blades look and seem to move as they should.

See second scan--a crummy one from a lesser scanner, so levels are much different, but same effect. This shot was taken from almost the opposite angle as the first picture.

Thanks again for your help.

Barry
 

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It was me who posted about this issue last week. After a running another test roll I found out it is really only with shots with bright sunny skys.

http://www.albumtown.com/showpic.php?aid=65159&uuid=16420&pid=985274

http://www.albumtown.com/showpic.ph...de_show=&slide_show_secs=0&preloadSlideShow=1

http://www.albumtown.com/showpic.ph...de_show=&slide_show_secs=0&preloadSlideShow=1

http://www.albumtown.com/showpic.ph...de_show=&slide_show_secs=0&preloadSlideShow=1

http://www.albumtown.com/showpic.ph...de_show=&slide_show_secs=0&preloadSlideShow=1


On all of my shots i have those 2 light and dark spots on the scan. They are not on the negitives. THANK YOU WALGREENS.
 
bmoc said:
Thanks for all your replies. I was using a Canon VT with a left-to-right shutter that was just adjusted--and yes, only happening with this lens and only on the right side toward the top of the frame (no matter the angle of the film plane relative to the sun). Using the small hood that came with the lens and no filter. Aperture blades look and seem to move as they should.

See second scan--a crummy one from a lesser scanner, so levels are much different, but same effect. This shot was taken from almost the opposite angle as the first picture.

Thanks again for your help.

Barry
Click to expand...

I was assuming you were using a Bessa in my previous post... I should know by now - Never assume anything!

Looking at this second image and noting what you said about the way your shutter operates, my guess is this is a shutter problem. The foreground is dark as well as the sky. You will probably find that it only occurs at one shutter speed, most likely the camera's fastest shutter speed. It looks as if the first curtain is delaying and the second one is catching it up. Its probably not the lens but you may have been using the fastest shutter speed with this lens and slower speeds with your other lenses.
 
I just noticed today, after seeing this thread, that one of Winogrand's famous pictures "Near Carmel" shows this pattern. the picture is in b/w, but it looks like it was taken on a very sunny day, and the sky occupies a significant portion of the frame.
 
No I have not. I am kinda new to the RF world and my camera and lens are both kind of new also. Is this an issue thats been around a while?
 
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