Archived posting to the Leica Users Group, 2001/02/20

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Subject: Re: [Leica] Leica 90mm Lens suggestions
From: "Dante A. Stella" <dante@umich.edu>
Date: Tue, 20 Feb 2001 22:46:13 -0500
References: <B6B89D13.5F95%howard.390@osu.edu>

Interesting, but what is the focusing screen he is comparing it to?  If it's a
split-image, the BL is going to be very, very short (like 18mm), and it's a slam
dunk for the RF in accuracy.

BUT if you have a low-contrast subject that does not include an eye or a nose or
some other frame of reference, both will fail.

Does he compare it to a microprism *spot*?  That's something that can be focused
rather easily without having straight lines.  I have been testing this for a while
on an M3 and an old Autoreflex T with center microprism spot only.  The SLR
generally seems to win with the 85 (vs 90), unless there is something to "lock
onto" with the rangefinder, in which case the RF wins.

Martin Howard wrote:

> Dante A. Stella jotted down the following:
>
> > There is no inherent rangefinder lens superiority for the 90mm length:
> > retrofocus is not an issue, compactness is not really an issue, and realworld
> > focusing is less accurate.  When you start talking about 85s and 90s, the SLR
> > world provides very stiff optical competition.
>
> Not quite true.  I don't have my copy here, but if I remember Günter
> Osterloh correctly from his M book, he delves into this somewhat at length,
> comparing the M6 (I believe) to a "typical" SLR (probably an R7) in terms of
> focussing accuracy.  The rangefinder was still more accurate at 90mm focal
> length, and I think about equal or maybe a tad less at 135mm.  Perhaps
> someone with the book at hand could look up the details.
>
> M.
>
> --
> Martin Howard                     |
> Visiting Scholar, CSEL, OSU       |   Even permanence is transitional.
> email: howard.390@osu.edu         |
> www: http://mvhoward.i.am/        +---------------------------------------

In reply to: Message from Martin Howard <howard.390@osu.edu> (Re: [Leica] Leica 90mm Lens suggestions)