| Author |
Message |
    
Haig Hovaness
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, February 14, 2004 - 04:34 pm: | 
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The infinity focus of my Oly 35RC is not consistent between f2.8 and f5.6. Do I have a bad sample of the lens? Has anyone else encountered this problem? |
charlie stobbs
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, February 15, 2004 - 09:02 am: |
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I am not sure if you mean changing the f stop moves the rangefinder or if only the image on the film is out of focus. If the latter, possibly the rangefinder is off but the increased depth of field at f5.6 and beyond masks the problem. |
rick oleson
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, February 15, 2004 - 09:41 pm: |
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do you see the focus indication in the rangefinder shift as you change apertures? if this is the case, your lens/shutter might be loose.
if you're observing the difference in your photos, i think charlie's onto it. the lens should not shift focus between stops, and i doubt that olympus made any examples bad enough to do so. |
Haig Hovaness
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, February 15, 2004 - 11:40 pm: |
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I found this problem by using Tomosy's great little autocollimator. This 35RC definitely focuses to infinity (on the film) at different distances wide open vs. stopped down. I know the problem is not in the test instrument, because my other lenses (mostly Nikon) check out fine. I can see how this could have made it through Olympus QA if they only tested the lens at one aperture. I guess I just got a bad sample |
rick oleson
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, February 16, 2004 - 07:10 am: |
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wow, i'm surprised. off the top of my head a focus shift with aperture sounds like spherical aberration. does the lens seem to perform reasonably well, or is it weird? (these are usuallly quite sharp)
rick |
Winfried
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, February 16, 2004 - 11:36 am: |
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I don't know what is wrong with this lens but I have severe doubts that a modern lens - even if it is below the usual quality level - shows such a focus shift at different apertures. |
