Archived posting to the Leica Users Group, 2004/10/15

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Subject: [Leica] Digital "crop factor"
From: mark at rabinergroup.com (Mark Rabiner)
Date: Fri Oct 15 17:05:45 2004

On 10/15/04 5:54 AM, "Douglas M. Sharp" <DouglasMSharp@netscape.net> typed:

> 
> 
> Mark Rabiner schrieb:
> 
>> Which means you're not using the full 43.3mm diameter of the image circle
>> the lens is projecting. (24x36)
>> Your only using a 30.1 image circles worth. (aps-c)
>>  
>> 
> Taking this a little further Mark, Does this infer that any lens , known
> to have poorer resolution towards
> the edges when used for 35mm, could in fact be a "good lens" when
> attached to a DSLR, as only a part of the image circle is actually used?
> I've often heard that people use adapters to attach MF lenses to 35mil
> cameras for just this reason.
> Douglas
> 

Well the problem with most cheap lenses I've learned on the LUG and the HUG
in the past five years is not their performance in the center sweat spot
stopped down.

It's at the ragged edges wide open.

So I'd think this could make for a lot of glass which couldn't cut the
mustard for a certain person on her 24x36 film; but could cut the Dijon with
relish on the APS-c (1.5 X) format. With Gusto.

Wide open usability is the other issue which doesn't get fixed on this one.

Other than the issue of stopping down improving your edge results.
But a low contrast soft image is a low contrast soft image at any image
circle I'd think.

A higher end lens gives you you hope good results wide wide open.

I'm thinking of starting a camera club. Calling it:

THE INNER CIRCLE OF CONFUSION

ICOC?


Mark Rabiner
Photography
Portland Oregon
http://rabinergroup.com/





Replies: Reply from kididdoc at cox.net (Steve Barbour) ([Leica] Digital "crop factor")
In reply to: Message from DouglasMSharp at netscape.net (Douglas M. Sharp) ([Leica] Digital "crop factor")