"Never try to teach a pig to sing. It wastes your time and annoys the pig."
seezee at Mercury Photo Bureau
seezee on Flickr
seezee's day-job at Messenger Web Design
I just finished a project where I shot 140 wet plate portraits in the studio. I never shoot indoors, always out in the sun, so I wanted to invest the least amount of money in lights. I bought two high powered LED floodlights at 6500K. These lights illuminated half a block in the promotional images however when I set them up they really weak and I quickly realized I needed a lot more light. I then built two sets of 4 foot florescent lights with 6 bulbs on each side for a total of 12 additional lights. My exposure was still 6 seconds at 4.5.
The thing to understand about LED's is that they can emit a very pure, narrow wavelength. I have a bright cluster of 48 red LED's that I can shine into my silver bath at close range to inspect the plate as I pull it (watching for little floaties) without any fear of fogging because the wavelength emission is so narrow and pure. When working with high-power UV LED's, that means you can have a lot of intensity in the UV wavelength, which won't be very bright visually, yet could fry your eyes.
My original response to Seezee was based on the thought, "well, it's no more UV-intense than the sun, which we deal with every day". But imagine if the sun was visually so dim that we could comfortably stare directly into it for long periods, yet it was still putting out the same volume of eye-damaging UV light. That's what you're dealing with when you use those pure UV LED's...
All things considered, I'd stay away from the UV LED's.
"I love my Verito lens, but I always have to sharpen everything in Photoshop..."
1. UV portion is almost useless - won`t pass through glass below 350nm. you need massive blue portion instead
2. hybrid (custom wavelenghts) LED modules are best for this . I use hybrid aquarium LEDs with 5 channels (10000K+15000K+420nm+445nm+455nm) and can get to 1s@f5.6 with OWH
with such short exposure time it would be possible to add two UV-channels - 360nm / 380nm or 380nm/400nm in place of those two white channels. and still you can light up the channels individually - blue/whites for setting things up and then blue+UV for exposure
What kind of studio strobe power is needed for an f/8 or f/11 exposure at head and shoulders portrait distance? Would 3600 W-s do the trick?
I have never done wet plate.
hey there i have a Hensel 3000ws head and for head and shoulder portrait with powersetting of p7.5 of p10 with aero ektar at f2.5 i got a good exposure why you want to shoot portrait f8 or f11? with p10 setting of my flash you feel the head and its VERY bright :-)
cheers janosch
The interest in f/8 and f/11 exposure is more easily attained critical sharpness due to a bit more DOF.
hm to me thats the beauty of LF :-) that razor thin DOF :-)
I'm about to start my wet plate journey and have been looking into the LED light issue.
I saw this video on YouTube by Lund Photographics where he shows how much more useful light that blue LEDs put out. So then I started my search for at least a 300w equivalent LED light source and found this light. It's more daylight balanced, not blue, so I looked up the spectral output to see if it would work and it seems like it will.
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