Archived posting to the Leica Users Group, 2001/07/30

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Subject: Re: [Leica] M rangefinder focusing techniques
From: "Steve LeHuray" <icommag@toad.net>
Date: Mon, 30 Jul 2001 09:31:13 -0500

Anthony asks:


> I notice that when focusing my M6, I spend about thirty seconds checking and
> double-checking to make absolutely sure that the two little images in the
> rangefinder are perfectly aligned.

Well I do not spend nearly that much time focusing


> I'm pretty sure that this is overkill, but I
> don't know how much accuracy is really necessary.

When focusing I do not take DOF into consideration as far as the main object
I am focusing. I do often think about the focus in front & back and set the
aperture accordingly.

> I'd like to know from those
> who have much longer experience with the M body just what sort of technique
you
> use for focusing so that something is indeed in focus without having to spent
> two minutes verifying things.

I started my photo career as a motorsports photog with an SLR in the days
before auto-focus and motor drive so I had lots of practice on focusing
quickly. When I got my first M, about 15 uears ago, I used to practice 'dry
shooting' on moving or even still objects but with no film in the camera.

Eventually I got into driving a race car (Formula 2000) myself and what a
lot of race car drivers do before a race is close their eyes and visualize
the entire race, meaning that, visualize the race from the start line and
the entire course, shift points, braking points etc. You can do the same
thing with a camera.

> I presume that there is some point at which
> "close enough" is identical to "perfectly lined up," but how do I know
reliably
> where that is?

I have never practised that.

> Rules of thumb or similar suggestions for speeding up the
> process are most welcome.  I've tried checking the DOF indications, but that
> takes as long as my attempts to get things perfectly aligned, so that doesn't
> seem to work very well.

See above.
>
> For example, when focusing at something 200 feet away, I note that the focus
> point isn't really at infinity, but in fact is very, very slightly short of
> infinity, but I'm never quite sure if I should try to make the adjustment.

I would not worry about 200 feet away. Check your infinity alignment by
focusing on an object 2 miles away like clouds.
>
> It's different from an SLR, in which the image is as sharp as it looks.  In a
> rangefinder, the focusing is extraordinarily accurate for shorter focal
lengths,
> and apparently a large discrepancy in the rangefinder may correspond to a
> virtually infinitesimal difference in the actual focus plane of the lens.  Not
> knowing how close I _really_ am to acceptable focus gives me enough of a
complex
> that I miss some shots while I try to see if those two images are _perfectly_
> aligned.

SL
>