[Leica] image quality and format/ 35 v. 120

[Paul Roark <proark@silcom.com>]

On Sun, 19 Mar 2000 Austin Franklin wrote in part:

>>>Perhaps you could share the resolution tests that showed this [film
flatness problem] phenomenon 
with us?<<<

Here is a series I recorded for a Rollei F.  I'd heard that the film
flatness of this design was better than the SL66 -- and I believe it is,
though my SL66 tests are too long ago for me to find.  The Rollei (3.5) was
shot at f11, which is what I generally use for landscapes and tripod shooting.

Film (Agfapan 25) wound to frame 1 and left for 14 hours: center resolution
85 lp/mm, edge 40.

Film wound to frame 2 and left to "relax" 20 minutes: center 50, edge 40.

Film wound to frame 3 and left to relax 4 minutes:  center 65, edge 38.
...
Film left on frame 6 for 2 hours.

Film wound to frame 7 and left to relax 5 minutes:  center 36, edge 48.

Note that when I have tested MF cameras in shooting quick series of shots,
there is no problem with film flatness.  As such, a person shooting a
wedding or some event where the film is not going to sit for a while really
doesn't need to worry about this.   Also, once the resolution is above 50,
it's not likely to be noticed much in most instances.  However, the ability
to enlarge the center section of a frame would certainly be affected.
Moreover, in my landscape shooting, the film often sits for an hour or more. 

>> [Paul Roark wrote] (Moreover, that Fuji GA645 Zi zoom is, in some ways, 
>>better than my Zeiss glass -- amazing.)
 > [Austin Franklin wrote] I have that camera, and I do not concur. It IS
>nice, but hardly a match 
>for my Zeiss Hasselblad lenses, ...

My resolution tests on Tmax 100, using the same test conditions:

SL66 Planar HFT at f11: center 75, edge 69; Zi at 90: center 80, edge 60.

SL66 Distagon 50 at f11: center 90, edge 42; Zi at 55: center 90, edge 70.

These results are really not that surprising.  The newest high end, low
ratio zooms are getting very good, especially at the wide end.  On the
other hand, retrofocus wide angles are usually second rate.  Note, however,
that the floating element 50 for the Hasselblad could well be the best of
the bunch.  Sadly, it is not available for the SL66.
________________

On Sun, 19 Mar 2000 Doc <CapsTeeth@aol.com> wrote, in part: 

>>>Has anyone ever mounted a Hasselblad lens on a 35mm adaptor ...<<<

I did an interesting but largely irrelevant test of the 150 Sonnar on 35
mm.  I adapted a bellows to be a mount for my SL66 lenses to fit onto a
Canon FD, complete with tilts, etc.  The test I remember, because it was
rather amazing, was with the 150 Sonnar at f 4.  It produced 100 lp/mm
center and "edge" -- a performance that was considerably better than any
lens I'd tested.  However, the test is not "fair" or comparable to a 35 mm
lens because I was able to focus the 150 on both the center and edge that I
measured due to the tilt capability of the mount.  I didn't measure the
other edge, and I assume it was terrible.  The vast majority of lenses I've
tested show some degree of curvature of field that decreases edge sharpness
in a normal test where the film plane and target are parallel and one
focuses on the center.  

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