[Leica] Newbie question about frame line accuracy

[mark at rabinergroup.com (Mark Rabiner)]

On 4/14/05 2:30 PM, "Henning Wulff" <henningw@archiphoto.com> typed:

> At 1:21 PM -0400 4/14/05, Scott McLoughlin wrote:
>> Why aren't the framelines in the M's (I have a TTL) very
>> accurate for framing?  Is there some special technical challenge
>> involved?
>> 
>> Scott
> 
> Rangefinders have two issues which make accurate framing close to
> impossible. One is parallax, 'cause you're viewing the subject from a
> different point than the lens sees it. Leicas, and most other RFs
> deal with this by moving the frame lines towards the lens as the lens
> is focussed closer. This is purely a function of the distance, so all
> frame lines can move the same amount.
> 
> The other is the fact that a lens, as it's moved away from the body
> sees a narrower angle of view. A 50mm lens moves some 4mm or so away
> from the body to focus at .7m. So instead of 51mm or so, it's now
> acting like a 55mm. I didn't do the math re: the extension, or look
> up the actual focal length of Leica lenses, but the ballpark is right.
> 
> Leica has designed the framelines so that at closest focussing
> distance, nothing gets cut off if you're shooting slides - the worst
> condition. So that defines the narrowest angle of view. If you shoot
> negatives at infinity that means that your viewfinder showed a lot
> more than you have on your negatives.
> 
> Since you have to move a longer focal length lens a lot more to focus
> at the same distance, the longer lenses have the greater error when
> shooting at infinity. 21mm lenses will be quite close; 135s have a
> _lot_ more on the neg at infinity.
> 
> The above means that medium format cameras, or any other larger
> format cameras have a lot more problems, as the 'standard' lens might
> be an 80 or 90, and therefore must extend a lot more for closer
> distances. That's why they sometimes have the feature that the
> framelines narrow and widen as you focus, to more accurately frame
> the picture. Cameras like the Koni-Omega had that. It does add
> complexity and sometimes caused problems as well as initial expense,
> but there were less framelines in those cameras compared with the
> Leicas as well. There were some 35's that had that feature as well.
> 
> Leicas of all vintages used the same criteria for frame lines. M3
> frame lines appear to be more accurate, but that was only because it
> was designed to focus to 1m (for lenses without eyes), and that meant
> that the extension of the lenses, and therefore the constriction of
> the angle of view was less.

I agree with Henning.
But/and there's for me one main thing.

When you look at your contact sheets on the light table with a loupe or
whatever you don't find yourself thinking:
"Wait a minute!? These are not my pictures! I didn't take these! I placed
the edge of the trash bin right at the edge of the frame! This has at least
one more inch showing past it! I want my money back!"

If your the kind of a guy who gets a Nikon F or Canon whatever which has
100% frame lines and line up an edge and print them full frame black border
then maybe you need a ground glass back for your Leica m.
Which they don't make. I don't think.

(100% frame lines  makes for slides in mounts which can ruin your day)

For me and most the whole thing turns out to be very viable.
It just works.
The non total accuracy of the frame lines have never affected my work.
And in the darkroom I almost always print full frame black border.


Mark Rabiner
Photography
Portland Oregon
http://rabinergroup.com/