Re: Start time for contact sheet

"Justin F. Knotzke" <[EMAIL PROTECTED]> wrote
> I've decided to create the [contact] sheet in my bathroom. I have a
> light which hangs from the ceiling directly over the [work area].
> [approximately] how long should I expose the paper ?

Nobody knows, tiddly pom, nobody knows ...

Usually folks in the darkroom try to adjust the light source for about
a 10 second exposure: it's not too long to wait; and it's not too 
short to time easily and accurately.

I'd start with a 15 watt bulb in the fixture.

Now, make a test strip:

 o Get a piece of cardboard or such

 o Cut a strip of paper about 2x10", lay the negatives
   on the paper and cover with glass

 o Make a 2 second exposure

 o Lay the cardboard on the glass, covering about 2"
   of the negative & paper

 o Expose again for 2 seconds

 o Again move the cardboard up 2 inches

 o Expose for 4 seconds

 o Repeat the process, exposing for 8 and then 16 seconds

 o Develop etc.

You will have a strip that shows exposures of 2, 4, 8, 16 & 32
seconds.  Pick or interpolate the time for the best exposure.
The paper only responds meaningfully for halving or doubling
the exposure, just like a 1 stop bracket when taking a picture.

If 2 seconds is too dark then use a lower wattage bulb.  If it's
as low as you can go then cover the tip of the bulb with masking
tape to cut down the light.  Make sure the attenuated light is
even across the exposing area.

If 32 seconds is too light then use a higher wattage bulb.

Remember the exposure sequence is 2, 2, 4, 8, 16 -- easy to
keep in your head if you are a -real- computer geek.

--
Nicholas O. Lindan, Cleveland, Ohio [EMAIL PROTECTED]
Consulting Engineer:  Electronics; Informatics; Photonics.