Archived posting to the Leica Users Group, 2000/01/04

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Subject: Re: [Leica] Technical Pan Sharpneness & Camera Vibration
From: Paul Roark <proark@silcom.com>
Date: Tue, 04 Jan 2000 10:31:43 -0800

I'm a Rollei medium format shooter who has been lurking here for a while.
I'd love to use 35 mm for pictorial shooting, but, so far, I've found the
results with 35 mm to be a bit disappointing -- not just due to film
sharpness but also due to the inherent vibration that focal plane shutters
seem to cause.  

As to TP sharpness, I find Tmax 100 actually is "sharper" -- in the sense
of fine detail relative contrast -- than TP up to about 90 lpm, depending
on developer and amount of adjacency effect.  Afgapan 25 is even more so.
In my view, TP is really more about fine grain than extreme sharpness.
However, its problems, including the difficulty of getting even
development, make it a difficult to use film.  In medium format, where the
development unevenness is much worse than 35 mm, the only developer I've
found that can give excellent results is Xtol 1:5.  However, you're looking
at an ISO of about 12 -- but with amazingly fine grain.  For medium format,
I find it hard to beat Tmax 100 for general, B&W pictorial work.

As a backpacker who likes to travel light,  I find the focal plane shutter
vibration issue to be a serious problem for 35 mm, and one where I'm
curious if the Leica M series' super smooth focal plane shutter makes a
noticeable difference.  With all of the non-Leica focal plane 35s I've
used, the focal plane shutters make it impossible to consistenly get top
resolution from a medium telephoto (about 85 mm) with a light tripod.  The
problems show up mostly where the direction of the shutter is such that the
mass of the tripod is not in line with the shutter movement (vertical
framing with most modern SLRs that have vertically traveling shutters), and
at speed between 1/4 and 1/60.   

In fact, I find that when one looks at total system weight, the Rollei GX
(medium format twin lens reflex) I use ends up being lighter than the 35 mm
system that would be needed to get equal sharpness -- even when enlarging
just the central portion of the 2 1/4 negative to get what is the
equivalent of a medium telephoto in 35 mm.  The GX's virtually
vibration-free leaf shutter is the difference.  It allows a very light
weight (e.g., Slik 800) tripod to give top resolution.

My question to the Leica experts (there must be a few sharpness freaks in
this group):  Is the Leica shutter smooth enough to give top resolution
with a 90 mm (or even 75) lens, shooting both horizontally and vertically,
on a light (less than 3 lb. total, including head) tripod, at all speeds?
I'd consider 90 lines per millimeter, in both the horizontal and vertical
sets of resolution lines on a test chart to be the minimum one should
expect at f 8 from a good lens with the camera on a tripod that is capable
of controlling the vibration from the system.  (If the answer is "no,"
those of you who like to shoot landscapes and travel light ought to take a
look at a good Rollei TLR.)

Paul Roark
http://www.silcom.com/~proark/photos.html