[Leica] Rangefinder error on M9

[hlritter at bex.net (Howard Ritter)]

John, Howard, Geoff?

Thank you for the information and the affirmation.

I did look at the M9 forum and saw snooty implications of poor technique, 
claims that the problem arises from the greater resolution and intolerance 
of a high-pixel digital sensor as compared to film, and statements to the 
effect that the problem is due to fact that the sensor is flatter and 
thinner than film, as well as a reference to the rumor that the 90 AA has 
been withdrawn to address focus problems (I was not able to confirm this 
thru Google).

To this I say, Hah! I've been using Leica Ms for a right few years now, and 
the middle-range images with my 90 AA on my M9 are just plain OUT OF FOCUS. 
It's not technique and it's not the unprecedentedly wonderful resolution of 
the sensor (which I very much doubt is superior to that of K64 in any case). 
They reveal less detail, viewed at the same size on the screen, than 
(correctly focused) images made from the same distance with the 35! When I 
stop down or shift the lens's focus a little, I get, guess what, SHARP 
IMAGES! When I take photos of the same subject with several other lenses 
(24, 35, and 50), they are in focus at infinity AND at the 7m distance in 
question. There is clearly something about the 90 AA that does not interact 
properly with the RF mechanism of my M9, and it seems not to be unique to 
mine. What is puzzling to me is why this should be. If the height of the 
focus cam at any given rotational position of the barrel corresponds, per 
the cam follower, to the plane of focus at that barrel position, then the RF 
will show registration for objects in the plane of focus, and I can't fathom 
the reason why there should be a difference with different lenses. All 
that's required is that the shape of the cam be right! It's only competent 
engineering to make sure that happens in a consistent way with each model of 
lens. 

My $0.02, as a well-known expert (...in hematology and oncology).

As for that statement about K64, what would be interesting is a series of 
pictures of the same subject matter with everything held constant but the 
recording medium. Now that I have a FF digital M, a film M or two, a couple 
rolls of K64, and 7 weeks until Duane's done with K processing...  I'll see 
what I can do.

?howard


On Nov 6, 2010, at 6:26 PM, Howard Ritter wrote:

> 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.