Re: [Leica] Rangefinder Terminology pt2

[John Collier <jbcollier@home.com>]

So we know that small apertures give us small circles of confusion which
makes the image seem to have great depth of focus, things both close and far
appear sharp. Larger apertures do the reverse where only a narrow area is
sharp in the image.

Now lets put it all together! The whole idea of the rangefinder is to place
the object you want focused in the image within the depth of focus of your
lens. It is much harder to do this with a large aperture lens, wide open, so
we use the longest based, highest magnification rangefinder we can. Simple!

Here is a website that explains it all with a little more technical jargon
but, to its credit, has a picture!

http://www.imx.nl/photosite/leica/m/bodies/rfaccuracy.html

and another picture off of the Leica homepage:

http://www.leica-camera.com/kultur/mythos/innovationen/messsucher/index_e.ht
ml

Now to your specific questions. The M3 has a higher magnification finder
(0.91x lifesize) than the M2 (0.72x lifesize) so focusing is easier. I like
the 0.72 finder as it has the best 35mm frame and that is my most used lens.
The high magnification finders have a 35mm frame that is hard to see or, in
the case of the M3, it does not have a 35mm frame at all. I also have
excellent eyesight so I do not need the extra magnification of the M3 or M6
0.85.

I hope this helps but I sure wish I could have included pictures! Please do
post any questions no matter how simple you think they are. That way you, I
and others, who are too shy, can learn more.

Your circularly and confused,

John Collier

> From: "Tony Salce" <NadinaTony@bigpond.com>
> 
> For someone reasonably new to rangefinders, could someone be so kind as to
> explain in simple english, what is meant by the following quote from Dick
> Gilcreast's article in the latest edition of Viewfinder, in respect of his
> preference of the M3 over the M2:
> 
> " In a rangefinder camera the RF needs to have enough base lenght in order
> for the indicated focus point to be WITHIN the rather narrow depth of field,
> so it made sense for Leitz to design their original M camera around these
> two lenses." (ie 50mm and 90 mm- this is my addition)
> 
> Could you also explain why the 0.72 magnification is not as good for the
> 50mm lens as compared with a 35mm lens ? I hope that question makes sense.
> 
> Actually I don't fully comprehend ( I am embarassed to admit) the
> distinction between the 0.92 magnification of say the M3 and the 0.72 of the
> M2.
>