Summicron 90mm/2 aperture problem

[KG1962]

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Hello,

 

A bit of help/advice please, I recently purchased a used Summicron 90mm/f2 lens (1993) for my Leica M.

 

I am having trouble getting sharp images, I have noticed that the aperture ring turns completely 360 degrees and clicks

at the different apertures and is free the rest of the way. When I download the images to lightroom the corresponding

aperture settings are wrong and are usually quoting roughly half of what I had set, stating F2 for when I had set F4 for example.....

 

I think I may have a faulty lens.......although I am a Leica newbie from Canon DSLR's (but in complete love with Leica) so go easy on me !!

 

Brgds

Kevin

+

[microview]

I don't think the aperture ring is supposed to rotate a full 360° and I am sure that my copy of that lens didn't do that (I now have the APO-Summicron); but the Lightroom program I understand can only approximate to the actual f-stop used for a shot. It's a topic often mentioned in the forum.

[lct]

[...] I have noticed that the aperture ring turns completely 360 degrees and clicks at the different apertures and is free the rest of the way.[...]

 

It should do that in no way. The aperture ring should stop turning at f/2 and f/16. Beware that 90/2 lenses are at the limit of RF accuracy at full aperture and that many legacy lenses need some digital calibration. Was the case for my 90/2 from 1995.  

[KG1962]

Thanks for your replies.... Lens couriered back to Leica dealer!!