Solar Enlarger revisited

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From: filmpro (filmpro@mac.com)
Date: 07/13/02-08:27:36 PM Z


Greetings!

i remember a while ago discussion of an enlarger powerful enough to
expose alt photo emulsions. i have a project to print Cyanotypes in the
24-36" wide range. The substrate will not be perfectly flat so I'm
thinking contact printing may not be optimal for sharpness.

I live in So. Cal so we have alot of sun. My idea would be to construct
an enlarger (similar to a Polaroid Daylab, where I could enlarge a 120
negative 6x6 to 6x17mm.

I was thinking about one of those large surplus military lenses? Don't
know where to start with that.

I could use some advice on the exposure math. For instance, if a contact
negative requires 20min to get a full exposure, how can I interpolate
that into what exposure would be required for an enlarger? I's been a
long time since i studied large format photography and bellow extension
compensation.

Would i be correct, that a mere lightmeter reading would not be
sufficent. IE If the light exposing the contact frame is EV 22. And my
Enlarger is projecting EV 2, that still would not account for the actual
UV transmission?

The second choice would be artificial light, but I know that area is
expensive. Getting an old plate burner.

Thanks for any input.

Max


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