View Full Version : UV content of lights for wet plate collodion-based processes.

22-Aug-2017, 14:34
I'm being seduced by ambrotypes but being able to use artificial light is a deal-breaker for me. I have old sledge hammer packs with enough joules in them to get me into the energy range people talk about for use with collodion. However, a couple of the heads need new tubes and the used market only has the UV-coated ones that are used in the fashion industry to prevent the dyes and brighteners in fabric from fluorescing. How much of a difference does it make to collodion using a strobe with a clear-glass tube vs one with anti-UV coating? I can't imagine that the uncoated tubes actually emit that much light or there would be warnings about using them without UV protection for your eyes. Beyond that, I don't know if collodion is primarily UV-sensitive or primarily blue-sensitive with a bit of response down into the UV (all I know is that it's red-blind).

So, those of you who actually do collodion-based processes, do you have any idea if clear-glass vs UV-coated strobe tubes is a deal breaker?

21-Sep-2017, 01:50
Contribution of UV portion to WPC exposure is negligible with common lenses.

"Well, some say combination of UV-rich light and vintage (uncoated) lens is fastest, but i would really doubt the UV transmittance of any glass. Looking at salted collodion spectral sensitivity, it starts at 500+nm, peaks at 450nm/420nm (bromide/iodide) and extends to UV.

But wikipedia says : "Most types of glass will allow longwave UV to pass, but absorb all the other UV wavelengths, usually from about 350 nm and below. For UV photography it is necessary to use specially developed lenses having elements made from fused quartz or quartz and fluorite."

So you still have only ~50nm of near-UV portion usable for exposure with common lenses and not this is not even in most sensitive region. "

Jason Greenberg Motamedi
21-Sep-2017, 07:19
I have used both (Speedotron) UV-coated and bare bulbs with wet plate and other color-blind processes and never noticed a difference in speed. So, I wouldn't worry about it.