[Leica] Rangefinder error on M9

[cummer at netvigator.com (H&ECummer)]

> Date: Sat, 6 Nov 2010 18:26:18 -0400
> From: Howard Ritter <hlritter at bex.net>
> Subject: [Leica] Rangefinder error on M9
> To: Leica Users Group <lug at leica-users.org>, MUGers at yahoogroups.com
> 
> I have just discovered that the RF on my M9 does not bring the 90 ASPH to 
> focus in at least the middle range, specifically 7 meters, although it 
> does so, as far as I've been able to tell, at infinity. I have not tested 
> it thoroughly at closer range, but I'll do so tomorrow during daylight 
> when I can use a low ISO.
> 
> I had seen comments on LUG/MUG along these lines previously but not paid 
> attention because I didn't yet have an M9. I recall seeing something about 
> lenses needing modding in order to focus properly on the M8 or M9, but 
> can't recall details.
> 
> This is very counterintuitive and perplexing to me. Given that the 
> flange-to-sensor distance on digital Ms is the same as the flange-to-film 
> distance on analog Ms, how does the problem arise at all, and why does a 
> modification of the lens or adjustment of the RF mechanism to accomodate 
> one combination not affect the modified unit's performance with other 
> combinations?
> 
> Any insight or advice would be highly appreciated.
> 
> ?howard

Hi Howard,
I had my 90 Cron APO adjusted for my M8 by the local Leica dealer - it 
exhibiting the problem you describe (correct focus at infinity - back focus 
in the middle ranges) and the adjustment did not solve the problem. I took 
it back and was told the lens was "within tolerances". I then took it to a 
local repairman, former Leica techician, who tweaked the rangefinder roller 
in my M8. That helped a bit, but made my other lenses focus less accurately. 
I finally gave up and sold the lens and replaced it with the 90 Elmarit  
which focuses spot on at every distance. I believe a couple of other LUggers 
have had a similar experience with their 90 APOs as well.
Howard (in Hong Kong)