[pure-silver] Re: The Quest
- From: Ken Sinclair <photo1@xxxxxxxxxxxxxxx>
- To: pure-silver@xxxxxxxxxxxxx
- Date: Thu, 14 Dec 2006 09:46:56 -0700
Adrienne,
"He also dabbles in darkroom cuisine, cooking up his negatives with
an enlarger designed for an electron microscope to achieve a degree
of image sharpness and contrast impossible to get with traditional
photographic equipment." (What kind of enlarger is that, I wonder??)
I have spent many hundreds of hours printing electron micrographs.
To achieve the remarkable sharpness from the negatives of
transmission electon micrographs, the enlarger system (Durst 138S)
use a rather expensive point source lamp... accompanied by a set of
"coated" condensers. The lens, if my memory serves me well enough was
a Rodenstock 150mm. the exposure to the paper must be made with the
lens wide open... ie. not stopped down the usual two stops down, and
the voltage to the 24v bulb controlled by a Variac. The interesting
thing that amazed me. was the ability to focus on the silver grains
WITHIN the thickness of the emulsion.
Unfortunately, every time there is to be a change in the print
magnification (from the negative) one has to "reset" the position of
lamp distance /condenser/lens system more carefully.
The point-source enlarger is also a wonderful.. and superior means of
making up to about 10:1 enlargements from ultra-microtome stained
tissue sections. The slide is placed in the enlarger and the image
projected directly to 4x5 (or larger) film in a film holder,
producing a superior quality of image that one will get using a 4 to
16x plan-apo objective on a microscope and the usual 35 mm film.
Ken
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