Blue/UV Light for Studio

I'm looking for some relatively affordable, easy to set up, won't-flip-breakers-or-burn-the-house-down lighting options that I can use in a studio for exposing dry plates. I've been playing around with the Rockland Colloid Tintype Parlor kit, and I feel like I'm getting some good results. But I've been outdoors and will want to bring the show indoors soon.

Anything that gives a rich source of blue light is what's needed here. Their website suggest the following: "high-wattage halogen bulb, mercury vapor lamp, sunlamp, arc light, blue photofloods, daylight fluorescents or UV fluorescents."

Lots of options here, but I'm looking to cut to the chase and would appreciate some informed advice. I'm exposing the plates at ISO 3. Outdoors, even in overcast light or shade, I can manage to keep exposures less than a second (I'm using a Crown Graphic, wide open of course). It would be nice to do the same indoors. These will be for portraits.

Thanks.

I would suggest a strobe, as they are often the most-compact and most-efficient way of getting lots of light. Some strobes have tubes (glass) that absorb UV, some have quartz tubes let it through and can therefore pose a bit of a sunburn hazard. That's kind of what you want in this case...

Mercury vapour HID lamps are cheap and bright (I have a couple of 250W ones that I use for lighting outdoor areas), but they're hard to look at because they're so bright. And because they're continuous (they usually can't be turned on/off at will, most only ignite when cold), you kind of need the UV-blocking layer otherwise you WILL burn your subject from the continuous exposure to all that UV. Oh, and they're an explosion hazard unless behind a toughened-glass fitting which will definitely eat all your UV.

Perhaps, then, a physics lesson is in order for me. Or just more research. I had been reading about artificial/studio lighting for wet plate, thinking that same would also apply to dry plate. Apparently, wet plate is blue sensitive, while dry plate is blue-green sensitive (orthochromatic). The Rockland documents don't make that very clear (or I just missed it).

So how does that change the equation? I hadn't considered strobes, based on my reading about wet plate. But perhaps it's more doable for dry plates?

In any case, I was considering the likes of this:
Dead Link Removed

If the emulsion can see blue+green, then it's not a big problem. You just need a really big bright light. Strobes are still the most efficient way to get that, but continuous lighting (including fluorescent and LED) can produce plenty of blue/green light.

If you want continuous light like that fotodiox thing, I would expect you'd be better off with a couple of 130W photoflood bulbs rather than a whole pile of little 30W bulbs packed in tightly that are mostly illuminating each other instead of your subject. They're also sold as grow bulbs. You could get one with high colour temp (6500K?) and low CRI and it would probably be more efficient for dry plate but unusable for colour photography.

Okay, you got me thinking about strobes again. Something like this has a 4800ws payload: http://www.speedotron.com/products/details/black_line/black_light_units/195

Is it overkill? Again, I'm looking at exposing ISO 3 orthochromatic material (dry plates and lith) at wide-openish apertures. This will be for 4x5 and 8x10.

The Speedotron you linked to requires a power pack to operate. That's a few grand more.

I've been looking at dry plates as well. My thoughts would be a bank of fluro tubes, but that is just my uneducated guess.

I'm curious to see how you go with this.

I'm not sure how one defines ISO speed points for ortho films so I'll just ignore the spectral difference; I'm pretty sure it doesn't matter because IIRC ISO is defined wrt white light. But I have a 1000W-s Bowens monolight that I can easily get (ISO100) f/45 from with a big softbox. ISO3 is 5 stops less, so I would expect you could budget for about f/8 from a single pop at 1000W-s through a softbox. A bit more if you use a silver umbrella (they're more efficient than softboxes), and heaps more if you directly illuminate. Lose 1 or 2 more stops to bellows factor and you probably need a lens that can do f/4 or a bigger light.

To illustrate just how much light you get from a strobe and how hard it is to get the same power from continuous light:
- a 1000W-s strobe produces about 40,000 lm-s of photons
- fluorescent and LED sources are about 80 lm/W
- that's 0.5s of exposure using a 1000W fluorescent fitting to get the same light as one flash pop
- 1000W of fluorescent grow-lamps is about $500 plus the cost of the fixture, and it acts as a 1kW room-heater
- you can't really put a 1kW heater in a softbox and expect it not to catch fire
- do you really want half second exposures instead of 1/250? for about the same price as buying a flash?

Since you're in the land of super-cheap secondhand photo gear, I expect you could get an old 4800W-s flash system for about what the continuous-light system costs, and it will perform far, far better.

IF you go down the Speedotron route, there are several things to keep in mind - Speedotron packs basically last forever, so no real need to buy one new unless you are planning to use it day in and day out 8+ hours a day. You can save thousands of dollars getting a used one. Also be aware the actual output for the 4800 w/s pack is only nominally higher than the 2400 w/s pack - I don't know why, but double-check the Speedotron specifications and you'll see. I have a Bowens/Calumet 2400 w/s pack that can use non-uv-blocking glass safety domes and non-uv-blocking flash tubes. They're worth looking into.

I saw on Ebay not long ago a large 660w fluorescent fixture that takes something like 8 or 12 fluorescent bulbs - that would be a good option especially if your wiring can't handle the draw of charging a 2400 or 4800 w/s pack.

Take a look at this video.
http://vimeo.com/41710130

polyglot said:

I'm not sure how one defines ISO speed points for ortho films so I'll just ignore the spectral difference; I'm pretty sure it doesn't matter because IIRC ISO is defined wrt white light. But I have a 1000W-s Bowens monolight that I can easily get (ISO100) f/45 from with a big softbox. ISO3 is 5 stops less, so I would expect you could budget for about f/8 from a single pop at 1000W-s through a softbox. A bit more if you use a silver umbrella (they're more efficient than softboxes), and heaps more if you directly illuminate. Lose 1 or 2 more stops to bellows factor and you probably need a lens that can do f/4 or a bigger light.

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That gets to the heart of the matter for me. It's the same math I've been doing, and it makes sense. So for all the reading I've been doing about, for example, wet plate shooters using two 4800 w/s pops to light their subject, it makes me think I'm missing something fundamental. Maybe they're rating their plates in fractions -- or spectral sensitivity does play into the equation. Or maybe it's just bravado.

Anyway, I like the idea of a 1000 w/s moonlight if it's up to the job. I'd rather not mess with power packs or rewiring the house.

Scott, thanks for the tip about the Speedotrons, and the light bank. These are still options, but if I can by with a lower powered moonlight, that would be ideal.

I'll look at the video later. Can't view it at work.

You can get a used Speedotron Black Line 2400ws kit (pack and a single head) for well under $1K if you shop carefully. A 1000ws moonlight will run you between $500-$1K depending on the outfit. There are two ranges of 240x packs from Speedotron - the older ones (2401/2403 IIRC) have different outlets for different power outputs - to reduce/increase power, you plug the head into a different socket in a different channel. If that's not enough, then plug in an extra head to the same channel to bleed off more power, and point that head at the floor or a far wall or something so it isn't putting light on the scene. The newer 2405cx pack allows you to adjust power to each channel without having to add additional heads, and you can split it asymmetrically. The old ones are also really big and really heavy.

If you're looking at working with wet/dry plates around ISO 3, you're going to want a LOT of power - this is one case where having too much isn't possible. I was doing some wet plate with strobe, and 2400 w/s was getting me f4.5 to maybe f5.6 at around 2 feet. And that was at ISO 1 or equivalent. You can always dial the power down if it's too much, but if you're not photographing still life subjects, extra pops of the flash aren't going to do you much good. Also, you get into calculating reciprocity failure for multiple flash pops - if one pop gets you f5.6, and two get you f8, it might be five or six to get f11 instead of four, and 14 or 15 to get f16.

Mainecoonmaniac said:

Take a look at this video.
http://vimeo.com/41710130

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That was very interesting. Is he using a ring light?!

Looks like it to me

bvy said:

That was very interesting. Is he using a ring light?!

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I think the camera lens is inside the ring light. Also, my guess from the catch light is there's a kicker light below the subject and another light top and left also.

bvy said:

That gets to the heart of the matter for me. It's the same math I've been doing, and it makes sense. So for all the reading I've been doing about, for example, wet plate shooters using two 4800 w/s pops to light their subject, it makes me think I'm missing something fundamental. Maybe they're rating their plates in fractions -- or spectral sensitivity does play into the equation. Or maybe it's just bravado.

Anyway, I like the idea of a 1000 w/s moonlight if it's up to the job. I'd rather not mess with power packs or rewiring the house.

Scott, thanks for the tip about the Speedotrons, and the light bank. These are still options, but if I can by with a lower powered moonlight, that would be ideal.

I'll look at the video later. Can't view it at work.

Click to expand...

Well, the modifier you use and how far it is from the subject both have a HUGE influence. If you move the box from 1m to 2m away, you're going to lose about 2 stops. If you use a larger, smoother or otherwise less-efficient softbox, drop another stop again.

IMHO, 1000W-s is (note that it's watt-seconds, i.e. Joules, not watt/second (watts per second, which is a nonsensical unit for photography)) is probably sufficient for your purposes if you're willing to get the light up close to the subject and not expect to light a large subject softly. If you want to have uniform lighting across a group of people, which requires the light to be further away, it will not cut it. If you want to use diffusion scrims, smaller apertures, etc, etc, it will not cut it. And IIRC wet plate is even slower than your dry plate, so that would explain the need for much more power there.

As TFC notes, you can get a pack+heads setup with about 1 stop more (electrical) power for about the same price as a monolight. If it's a fairly modern pack then that's a good deal but if it's an ancient Norman or something then it's not, because flash tube efficiencies have improved markedly since the 1970s. My modern 1000W-s monolight produces as much light as an ancient 2400W-s pack despite providing less than half the electrical energy to the tube. If you mortgage the house and buy a new Profoto 2400W-s pack, it will get 1.5 stops more than my monolight, as expected from the difference in electrical-energy rating.

In terms of "oh, my wiring", it shouldn't be that bad unless you buy a really old or fast-recycling pack. Ignore the flash energy rating for now and see if you can google the actual input power consumption, you should find that it's not more than about 1kW for even the largest modern flashes. Less if you configure them as modeling-lights-off while recycling, since the modeling lights are hugely power-hungry. Putting in CFL modeling lights (they're typically 250W-500W halogens) will save a lot of heat and power.

Oh how I wish flashes were rates in lm-s not W-s. Damn manufacturers and their proxy metrics.

Thank you everyone, polyglot especially. I have a better understanding of all this now. I think when the time comes, I'll go down the Speedotron route. I hear they are workhorses, and they appear to sell for a song on the second-hand market.

I'm going to take this off topic for a sec.

Bvy, do you have any examples of your dry plate work online to view? I'm actually finding it hard to see good examples of what can be achieved with the Rockland kits.

Cheers

hoffy said:

Bvy, do you have any examples of your dry plate work online to view? I'm actually finding it hard to see good examples of what can be achieved with the Rockland kits.

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There are a few recent things in my gallery, but I haven't shared a whole at this point, as I'm still fine tuning my workflow and results. For someone who's using the kit consistently, professionally, and getting good results, check out Sean McCormick's site: Dead Link Removed