Archived posting to the Leica Users Group, 2001/06/21

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Subject: Re: [Leica] Lens Not sharp @ f16
From: Doug Herr <telyt@earthlink.net>
Date: 21 Jun 2001 11:20:59 -0700

On Thu, 21 June 2001, "Edward Mortimer" wrote:

> 
> 
> 
> Hi Folks,
>         As you may know I have owned a Leica M6 'classic' for about a month 
> now. My first results have been really good and I have been impressed by it 
> sharpness. But recently I have noticed that when shooting at F16 the 
> resulting image isnt sharp, infact its almost blurry. Even when focusing on 
> infinity, subjects at the horizon seem quite fuzzy. Its baffling me because 
> at other F#s the images are clean and v sharp. Might it be marks on the 
> lens, that arent normally a problem at other F#s, but are degrading the 
> image when shooting at a v small aperture? What do you think? The lens is 
> G'teed so Ill probably take it back, I just wondered what the hell it was!
> Many Regards
> 
> Edd
> 

Edd,

Any lens' performance degrades at small apertures because of the greater influence of diffraction as the light passes the aperture blades vs. the normal image-forming light waves.  I can't say from here whether the degree of degradation in your lens is normal or not but in general don't use the smallest apertures on ANY lens unless you have to.

Doug Herr
Birdman of Sacramento
http://www.wildlightphoto.com
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