Re: [OM] OM wides (21/2, et al)

[Chuck Norcutt]

Good point but focusing error should hopefully be accommodated within 
the DoF since he used a flat target at 1:40 magnification.  That's 2.1 
meters for a 50mm.  Even at f/1.4 the DoF on either side of the target 
ranges from about 77mm in front to 84mm behind.  By f/16 it's more than 
1/2 meter in front to more than 1-1/2 meters behind.  Perhaps all part 
of the warning not to compare except across a full letter grade.

Chuck Norcutt


Wayne Harridge wrote:
>> Me thinks you guys are being overly severe.  I distinctly remember the
>> 200/4 having an apparently sympathetic vibration problem.  I haven't
>> checked all the lenses yet but I did look over a lot of them up to
>> 135mm
>> and don't see any significant problem there.  It's very difficult to
>> get
>> a true indication of the difference between mirror lock on the OM-1 and
>> mirror pre-fire on the 2s and up.  The problem is that most of the
>> tests
>> using different cameras also use different samples of the lenses.  In
>> most cases the differences don't amount to a full grade and, since they
>> aren't paired tests, it's not valid to evaluate one as better than
>> another.  Probably the biggest shock is not the effect of the diaphragm
>> slap but the performance difference of different lens samples.
>>
> 
> ...and what about focussing accuracy ?
> 
> ...Wayne
> 
> 
> 
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