Re: [Leica] Leica-Users List Digest V3 #72

[Summicron1 <Summicron1@aol.com>]

someone wrote:Subject: [Leica] M-nightmares

You guys are killing me with all this talk about how the M6 focusses better

than R with wides and standard lenses.  Jim is this true?  I have had a few

screw-ups with soft images, but I just chalked them up to poor depth of

field.  Could it be that I wasn't focussed properly?  I'd hate to think so!

 Also no one doubts the focussing capacity of the M-series, but what about

the CL?



Thanks,



James 

My response: Comparing the focusing of wide angle lenses on an R and an M is
comparing apples and oranges. The R is a ground glass focusing, with a little
teensy-tiny "rangefinder" split image system stuck in the middle. The M, on
the other hand, is a true rangefinder, with a couple of inches of separation
between the two range finder imaging mirrors.

So, for wide angle lenses the focus of an R is going to be more difficult if
you wish to be precise -- the image on the ground glass can be actually out of
focus slightly and still look sharp (depending on how fine the grindings on
the glass are, which can not possibly be as fine as the resolution of the
lens.) The wider angle the lens, the less value is the little teensy-tiny
rangefinder spot as well -- there just isn't enough separation there to work
with.

An M, on the other hand really shines with wide angle lenses because its
rangefinder has no idea what sort of lens it is working with. It is as precise
as the machining on the focusing cam of the lens, but with any lens it tells
you that something is in focus on that plane by positive coincidence of two
images. 

On the other hand, a rangefinder gives you no visual idea of depth of field,
and with very long lenses (longer than 135) the separation is not enough,
while a ground glass focusing camera comes into its own.

So, buy two camera systems: R for long lenses, M for short. 

As to the CL, a moment's thought will tell you that, fine a machine though it
is, its rangefinder is not as good as an M because the base is shorter. That's
why the owner's manual says not to use a 90 2.8 or wider on it..

charlie trentelman
ogden, utah