Archived posting to the Leica Users Group, 1999/09/30

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Subject: Re: [Leica] Which one is the Leica?
From: Alexey Merz <alexey@webcom.com>
Date: Thu, 30 Sep 1999 09:12:24 -0400

Anthony Atieleski wrote:

>> As an engineer you should be able to figure out the
>> obvious. So here's a beginning for dumb engineers:
>> same distance from film plane, same aperture, same
>> shutter time, same lighting, same object in frame, same
>> camera support.

>As an engineer, I know that it is impossible for everything to 
>be the same. Therefore it is necessary to specify the acceptable 
>tolerances for "sameness."

As a scientist who uses high-end Zeiss, Leica, and Nikon microscopes 
nearly every working day, *I* know from experience that in microscopes 
and cameras, optical differences between lenses *do* make real world 
differences in one's results. I also know that when you compare two 
pieces of equipment, it is wise to hold all other variables as
constant 
as possible. 

Otherwise, you don't know whether the differences that you see (or do
not see) are due to differences in the things being compared or due
to noise (i.e., the things not controlled). You SAY that it is necessary
to "specify the acceptable tolerances for 'sameness'". But you did no
such thing; instead you posted two photos taken HANDHELD at different 
times of day - with different lighting, different subject contrasts 
(etc., etc.).

So the MOST you can say is that when shot sloppily, the two cameras
produce similar results. But that is really quite meaningless, because
when you're sloppy there will be a range of results produced. Sometimes
your hands will shake more than others. Thus under those conditions, for
a valid comparison, you'd need a SAMPLE of PAIRED images, or a much 
LARGER sample of UNPAIRED images to say anything meaningful about whether
one lens is better. 

What IS clear is that YOU do not care about technique or the (technical)
quality of your results enough that you will see "meaningful"
differences 
between the two lenses. So stop prattling about whether there are differences
between the lenses, and take some pictures that you like!

I shan't comment further on this.

- -Alexey