Immages from the 790 f:5,4 Meniscus Lens

[Reinhold Schable]

Photos taken with the 790mm f:5.4 Wollaston Meniscus lens...

I made two paper negatives: one shot almost wide open, and one at f:22 to give you some idea of the range of soft/sharp image formation of this lens.

The lens was pre-mounted on a 8.5" square board and clamped to the front posts of my KB Canham 8x20" camera. The Gazebo was 75' (23 meters) away in late morning sunlight. Focusing wide open was very fast on the sunlit vertical fence, no re-focusing was done for each aperture card. I let the inherent depth of focus for this lens express itself at each aperture without tweaking it each time. (I felt it was "right on" at each f:stop).

The Paper Negatives are on 8x20" PhotoWarehouse VC RC paper, (pre flashed 3 seconds @f:32)
Exposures were ±1.5 seconds @ f:6.7, and 6 seconds @ f:22 (using a cardboard version of Ansel's hat)
Developed 7.5 & 14 minutes in old, used Ansco 130, diluted 1+15.
The central 8x12" area was scanned (Epson V700); levels adjusted a bit , but NO sharpening.

I'd love to try the same test with portraits, but my bellows draw is wayyyy too short...

Some lens details here:
http://www.apug.org/forums/forum379/...available.html

Reinhold

As usual, ignore my spelling (Immages)...

[Andrew O'Neill]

Very interesting. Where did you source the meniscus from, Reinhold?

[sanking]

Very interesting. Where did you source the meniscus from, Reinhold?

Andrew,

A good source for positive meniscus lenses is http://www.surplusshed.com/

There is a lens finder service that allows you to find the type lens and focal length desired.

Sandy