A few days ago John Thurston announced his suc-
cess with adapting the 55mm fl lenses to his
TL-120 camera.

Mike Davis was able to check out several of the
test slides.

Mike indicated the slides were acceptably sharp,
(at f/22), from 4 1/4 ft to infinity, and were
spectacularly sharp, from 5ft to infinity.

Mike does have, extremely, high standards, regard-
ing sharpness.

About 1 1/2 years ago, Oleg V. discussed Viewer
Discomfort. He mentioned the theory, that MAOFD
could be determined, by dividing the focal length
of the viewer lenses by 30, (FL/30).

Mike Davis could provide a test of this allegation
by shooting some test slides with his pair of 43mm
lensed Mamiya 7 cameras.

With the lenses spaced about 125mm apart, he could
shoot infinity scenes, with the near points at 5ft,
6ft, 7ft, 8ft, and 10ft.

The near points should be verticals that cross
infinity.

The resulting OFDs' will be, approximately:

5ft = 3.5mm, OFD
6ft = 3.0mm, OFD
7ft = 2.6mm, OFD
8ft = 2.2mm, OFD
10ft = 1.8mm, OFD.

DoF should not be a problem with the 43mm fl lenses,
at f/22.

The resulting slides could be sent around in a MF folio.

The MF members could, on their own, decide what their OFD
limits are. At the same time, the validity of the, (FL/30),
theory could be tested.

In the case of using a Saturn, (with 78mm fl lenses), the
MAOFD should be, according to the FL/30 theory, about 2.6mm.


Just a suggestion,

DON