[Leica] 90 APO Asph on M8

[henningw at archiphoto.com (Henning Wulff)]

At 1:44 PM +0800 5/23/09, Thein Onn Ming wrote:
>Have you tried that 2mm hex wrench tweak? There's a little bolt 
>inside the roller cam that can be easily adjusted for front/back 
>focus. After adjusting my 90 pre AA cron for infinity focus with the 
>cam (set the lens barrel to infinity, pick a really distant object 
>like a mountain range >20km away and adjust for overlap), everything 
>was a bit easier. My problem was that my eyes aren't quite good 
>enough to overlap the RF patch precisely if there isn't a sharp line 
>or two in the scene.
>
>Ming
>

I would advise against trying to adjust for the 90 AA in that way. 
Firstly, it could very well be the 90 that is the problem. Secondly, 
if you fiddle with the infinity setting for one lens, the close up 
performance with it, and all other lenses could suffer. The 
adjustment is quite unforgiving with the longer faster lenses, and my 
advice is to give it to someone who has experience and the equipment 
to do a full adjustment.

As Howard Cummer has mentioned, I had issues with my 90 and I 
considered sending it and a camera to get adjusted, but by that time 
I realized that I was shooting more with my 75's anyway. I did send 
off one camera and some fast lenses including the Noctilux to Solms 
last year along with some other lenses getting coded, and everything 
came back in fine adjustment. I can now focus the Noctilux accurately 
wide open on both cameras, as well as the 75/1.4. It was worth the 
effort and money (and the anxiety in sending all those many items off 
in a little parcel).

-- 

    *            Henning J. Wulff
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