Pre-sensitizing silver halide without TEA?

Colin Kaminski · Post by **Colin Kaminski** » Fri Mar 20, 2009 2:51 pm

BobH wrote:Lumicon used to sell a hydrogen hypersensitizing kit for astrophotography, if I remember correctly. Now there's a hobby deader than holography! Silver halide astrophotography. RIP! :whistle:

I got to shoot exposures on a hand guided Shmitt-Cass Camera in the 70s for a night. I think it was a 16". We were going after a nebula but I don't remember what one. I remember thinking designing a telescope with no EP was kind of silly but no where near as silly as hand guiding for 45 minutes.

Justin W · Post by **Justin W** » Sat Mar 21, 2009 2:23 pm

[quote="Ed Wesly"]It should be about 1/4 of the usual exposure. quote]

Get out of town!

You're saying an ammonia or hydrogen or possibly even water wash and drying before exposure could make the 46 second off-axis reflection shoot I'm setting up require only 11.5 seconds!?!?

Oh
My
God

That changes everything.
Hell, I could make an 11-second hologram in the back of a moving car

Noise!
Do hypersensitized emulsions ever make poor holograms?
Loss in resolution, other problems, etc?
Seems like such a significant gain in speed makes me wonder there must be reasons not to supercharge one's film...

BobH · Post by **BobH** » Sat Mar 21, 2009 2:50 pm

All of the reflection holograms I've made on Agfa or Ilford materials were hypersensitized in water or water with TEA in it. You just need to be able to get it to dry evenly after the treatment in safelight. That usually means squeegeeing, which isn't difficult when you get in the habbit. But I always work on glass plates, not film.