Richard Knoppow (dickburk@ix.netcom.com)
Tue, 19 Jan 1999 14:29:01 -0800
At 06:15 AM 1/19/99 -0800, you wrote:
>Greetings!
>
> What is the reading size of the densitometer?
>
> On the top of the arm there is a threaded female socket.
>What does this connect to and what is it's function?
>
> Yours,
>
> Rich Lahrson
> tripspud@hooked.net
>
>
On my analyser the hole measures about one millimeter. Since this
aperture is on the illuminating side the the scattering of light in the
emulsion probably makes the sampled area larger. On my Analyser the hole
is in the middle of a "cross hair" area which is illuminated. Its upper
surface is painted flat white. When the arm is raised a light attenuator
and diffuser is brought into place below this target so that the area of
the film being measured can be seen clearly. When the arm is pushed down
for making the measurement the diffuser is moved out of the light path.
My Analyser does not have a threaded socket on top of the arm.
The "S" switch lights a "Safelight" for the meter. The Analyser was
designed so that it could also be used as an illumination meter for
checking the brightness of enlargers and contact printers to determine
exposure. So the meter movement is equipped with a red lamp to act as a
safelight. This is why the meter has a foot-candle scale on it.
Originally these analysers came with a light attenuator for the
photo-cell so that readings could be made on contact printing machines, and
a circular slide rule for calculating gamma, etc. from the readings.
It is still a very useful tool for B&W work. The calibration will be
about right as long as the Selenium cell is OK. This should be checked
with a step wedge. Selenium cells become non-linear when they are damaged.
On the analyser this will show up as low densities reading too low compared
to high densities.
Its the same problem as found with Selenium cell exposure meters. Since
the meter has the foot-candle scale one could also check the cell by
comparing it to a known good light meter with an illumination scale on it
(most have one).
----
Richard Knoppow
Los Angeles,Ca.
dickburk@ix.netcom.com
This archive was generated by hypermail 2.0b3 on Sat Nov 06 1999 - 10:06:43