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Re: [OM] ( DZ OM ) Value for money?

Subject: Re: [OM] ( DZ OM ) Value for money?
From: Chuck Norcutt <chucknorcutt@xxxxxxxxxxxxxxxx>
Date: Tue, 14 Jul 2009 12:00:52 -0400
Tech Pan had a resolution of 100 lpmm.  That's for low contrast subjects 
which is how the resolution is typically stated.  For high contrast 
subjects the resolution is 320 lpmm.  For most films the high contrast 
resolution is in the range of 2-3 times the low contrast resolution. 
But I don't recall what Modern used for test targets nor do I know how 
100 lpmm works out in a "system" computation with a typical lens of the 
1970s or 1980s.  But 50 lpmm is a typical test result number that I can 
agree with from memory.

But I don't think you should be concerned about the additional "steps" 
between exposure and evaluation.  Presumably the film was developed and 
directly  examined with a loupe.  There should have been nothing else to 
degrade the results other than the loupe and the eye of the examiner.

Chuck Norcutt


Dawid Loubser wrote:
> I have to disagree with the statement below, the films usually used to  
> test lenses
> (at least Pan F, typically the old defunct Tech Pan, and sometimes  
> even copy/microfilms,
> offer vastly more resolution than current DSLR sensors.
> 
> I think the 'process' was more at fault, there are many more image- 
> degrading steps
> involved in getting a film image to a state where one can make  
> observations about
> lens quality.
> 
> Am I wrong?
> 
> 
> On 14 Jul 2009, at 7:08 AM, C.H.Ling wrote:
> 
> <snip>
> 
>> while Modern Photography only seen 50 lines per mm with film, he  
>> believe the different is
>> limitation of film.
> 
> <snip>
> 
-- 
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