Archived posting to the Leica Users Group, 2010/05/26

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Subject: [Leica] Fwd: Shattered M8 sensor glass update (780 Euros) + soft focus confusion
From: red735i at earthlink.net (red735i at earthlink.net)
Date: Wed, 26 May 2010 21:29:18 -0700 (GMT-07:00)

Peter...you understand correctly my words.  I test at infinity and some 
other close distance, usually around 5 feet.  I evaluate with a loupe.  I do 
make one difference from your test, in that I use a broom stick as my focus 
target up close.  With the tape measure as the way I tell if it is out in 
front of or behind the focal plane.  How much it is out does not concern me, 
as it is either right or not.  If not, it must go in for service.  The 
brooom stick gives me something pretty easy to focus on.  BTW, sometimes I 
use a brick wall for infinity.... you can be sure to find problems with this 
kind of target.

Your test using a flat bed scanner ( I also have a VT 700) is subject to 
film flatness of the plastic holder.  film can be distorted along its width 
and more so along its length ( 36mm direction to be clear.)


I looked a a few images, and could not ID the focal plane, and I am usually 
pretty good at it.  Could be the 72ppi of the display.  What did you find?

I had forgotten that you were doing this test at different distances..... 
but I do not understand the test..... the focus cam is linear.  If it is 
out, it is out at infinity or at closest distance or both.  This can be 
determined by testing at closest distance and again at infinity.... ( like a 
1/2 mile away power line).  In between these 2 points, the focus may be out 
or not, but it really gives no more info for body repair.  ( might tell you 
the lens is whacked out, but I would need to think about that some more....) 
 As I understand the body tweaks, it is inifninty or closest focus only.  
The focus cam makes the in between points pretty much hard wired.  I have 
heard of regrinding the lens focus cam, but that was really rare.

But back to brass tacks...  what did you find?