lights for wetplates

[Jbuck]

what would be a good starters set for lights with lightformers ( softbox ) that would be strong enough for making wetplates?

probably the 250w modelling lights from a (lets say) bowens 500 gemni set are far from being strong enough.

thanks!

[StoneNYC]

Wet plate responds to UV light best so you want something that produces a lot of UV power, you're probably going to want something more like 48000ws or more.

This is why many choose natural light as the sun has a lot more UV than most strobes.

I am NOT a WP photographer yet, but this is what I have surmised thus far from reading a lot of people with the same issue as you have.

[anton orlov]

I prefer natural light any time for WP. But when I work inside I use flash and haven't used continuous (so can't weigh in there). Stone is right there - most people use over 4000ws WITH soft boxes or other diffusion. I use 2400ws with no diffusion. And of course everything will depend on how fast your collodion is and how fast your lens is. Find an f1 lens and mix your collodion fresh and you can probably get away with a Sylvania flash bulb

[Mark Sawyer]

Wet plate is an area where one always seems to need as much light as one can get. Modifiers like a soft box or umbrella reflector steal away at least half the light...

[vinny]

Wet plate is an area where one always seems to need as much light as one can get. Modifiers like a soft box or umbrella reflector steal away at least half the light...

That's one of the reasons most wet playe work shot with lights looks like garbage. Small, Bare sources.

[andy]

I have a friend who rigged up a number of compact florescent bulbs on light stands--probably 7-10 on each stand for a simple, inexpensive, and effect continuous light source for tintypes.

[AlexGard]

Continuous 65 to 85w cfl bulbs 5500k

A bank of five 65w's and then one or two single 85w's for other secondary light (rim etc) does the trick for me. 5 seconds rated at Iso 1 with pushed development

[knuf]

Hi, i`m currently building two lights for wetplates :

1. made of 24 panels with 48 5630 cold white LEDs each - 1152 LEDs total from 40cm*20cm surface. It should give around 20k lumens at lower end of 5630 specs, 30k lumens somewhere in the middle and i hope being able to push it for short exposure periods to 40k lumens using adjustable power source (still not at max value). almost done - it weighs about 5kg (LEDs, cables, heatsink) so i consider buying cheap stand for PA speakers (tens of kg of weight capacity) instead of bothering with cheap studio lights tripod (4kg capacity).

2. made of 4 high power LED chips (90W each) made for aquarium lights. These are hybrid leds with 5 separate channels consisting of chips designed in blue part of the spectrum but with slightly different wavelengths resulting in broader blue spectrum (opposed to 20-30nm width for single wavelength emmiters) :

Channel 1) 10S x 2P 10000K 30-36VDC 700MA
Channel 2) 10S x 2P 455nm 30-36VDC 700MA
Channel 3) 10S x 420nm 30-36VDC 350MA
Channel 4) 10S x 2P 445nm 30-36VDC 700MA
Channel 5) 10S x 2P 15000K 30-36VDC 700MA

[StoneNYC]

Hi, i`m currently building two lights for wetplates :

1. made of 24 panels with 48 5630 cold white LEDs each - 1152 LEDs total from 40cm*20cm surface. It should give around 20k lumens at lower end of 5630 specs, 30k lumens somewhere in the middle and i hope being able to push it for short exposure periods to 40k lumens using adjustable power source (still not at max value). almost done - it weighs about 5kg (LEDs, cables, heatsink) so i consider buying cheap stand for PA speakers (tens of kg of weight capacity) instead of bothering with cheap studio lights tripod (4kg capacity).

2. made of 4 high power LED chips (90W each) made for aquarium lights. These are hybrid leds with 5 separate channels consisting of chips designed in blue part of the spectrum but with slightly different wavelengths resulting in broader blue spectrum (opposed to 20-30nm width for single wavelength emmiters) :

Channel 1) 10S x 2P 10000K 30-36VDC 700MA
Channel 2) 10S x 2P 455nm 30-36VDC 700MA
Channel 3) 10S x 420nm 30-36VDC 350MA
Channel 4) 10S x 2P 445nm 30-36VDC 700MA
Channel 5) 10S x 2P 15000K 30-36VDC 700MA

I thought wet plate relied on UV light? Do they make LED's that emit high UV now?

[knuf]

I thought wet plate relied on UV light? Do they make LED's that emit high UV now?

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. Next thing is that conventional UV-rich light sources as mercury vapor lamps or MH should be really considered as "hot", uncomfortable or even dangerous for sitter.

That`s why i think that in searching for ideal wetplates light, it would be better to find source which is rich in 400-500nm band and hybrid LEDs seem ideal in this. Broad blue light should be more comfortable as eye sensitivity is lower in blue (opposed to collodion) and LEDs can be switched on/off immediately and repeatedly or diminished (opposed to gas discharge lamps) saving the sitter from unnecessary exposure to near-UV/blue light (see UV / blue light hazard).

And the best thing : Those hybrid aquarium LEDs were designed by/for different community. Some manufacturers offer customized LEDs - you can have any combination of chips with wavelengths from 350nm to 800nm easily. So we could have a 90w LED with channels in 360nm,380nm,400nm,420nm,450nm.