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[OM] Re: The 5D and manual focus OM lenses

Subject: [OM] Re: The 5D and manual focus OM lenses
From: Chuck Norcutt <chucknorcutt@xxxxxxxxxxx>
Date: Mon, 19 Jun 2006 06:34:32 -0400
I think you're probably correct which is why I parenthetically said 
"perhaps".  What I actually discovered was that my eyesight is so bad 
that I couldn't have proved this point one way or the other.

If I get back to testing I may try readjusting the diopter and using my 
reading glasses which are corrected for my astigmatism.  It will be 
interesting to see if it makes any difference given that the screen is 
not optimized for manual focus.

One thought I haven't addressed before is that I have no knowledge of 
whether or not I can focus my OM-2s with 2-13 screen any more accurately 
than I'm doing with the 5D.  Blowing up a 5D image in order to do 1:1 
pixel peeping may be a such a stringent focusing test that maybe I can't 
do it with the OM either.

Chuck Norcutt

Tim Hughes wrote:

> I have not been following this thread so maybe this is redundant.
> 
> Chuck wrote:
> 
>>>Before futzing around with focusing screen shims to reposition the 
> 
> screen I decided that I should be able to accomplish the same thing 
> (perhaps) by deliberately misadjusting the diopter control. 
> <<
> Chuck in general , I would guess you can't adjust the diopter and hope to 
> help a misplaced screen.
> The diopter is to help your eyes focus correctly to the distance of the 
> screen (output side). If
> the image on the input side "ground glass" is not correctly placed on intput 
> side, it should not
> help to misfocus the outpout on the already unsharp image at what would be 
> the true focus point. 
> Maybe there could be some effect if the screen is so clear it does not form a 
> true conjugate image
> plane at the screen location?  Does not seem likely.
> 
> I think the issue in general if everything is correctly adjusted, is the 
> focus screens chosen in
> auto-focus DSLRS, do not have designs suitable for manual focus anyway, with 
> the correct
> coraseness of structure or focus aids like split prism etc. 
> 
> Tim Hughes
> 
> 
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