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Edanylycha
27-Feb-2017, 06:19
Hello all,
I am very new to this style of photography, I've just finished building my own 8x10 wet plate collodion camera and have just begun mixing my first batch of chemicals. Seeing as this is all experimental for me I'm trying to keep it low budget. Has anyone had any experience with using LED lighting for studio wet plate photography? Any information will be greatly appreciated!
Many thanks,
Ethan

Jim Noel
27-Feb-2017, 09:38
I haven't tried it with wet plate, but if any LED's will work it will be those which put out in the UV spectrum. The "white light" ones may also work.

goamules
27-Feb-2017, 11:32
Mark will weigh in soon, but you need a LOT of light for wetplate. Compact florescents, blacklights, and all the rest have been used. But usually fail. They can create a weird skin tone, or the sitter has to be staring into 3 banks of light with as much candlepower as the sun. It's ISO 1 afterall. Mark uses strobes to good effect.

Edanylycha
27-Feb-2017, 16:35
I've read that lights in the 5500k range are correct for wet plate, Is this accurate?

Mark Sawyer
27-Feb-2017, 20:45
Mark will weigh in soon, but you need a LOT of light for wetplate. Compact florescents, blacklights, and all the rest have been used. But usually fail. They can create a weird skin tone, or the sitter has to be staring into 3 banks of light with as much candlepower as the sun. It's ISO 1 afterall. Mark uses strobes to good effect.

Oh yeah, drag me into it... :rolleyes:

I haven't played with LED's, so I can't comment other than the already stated need for UV and blue wavelengths. But I've used CFL's for still life, (yup, 5500k, Edanylycha) with good results. But for portraits, any hot lights will make the subject very uncomfortable, which generally has a very negative effect on the results. Go with strobes there.

DKirk
28-Feb-2017, 02:20
More for the printing side of things, but you could have a look at http://thewetprint.com/en/2016/09/16/exposure-unit-part-1-design/ to give you a rough idea for one way to use LEDs. Though if you're photographing people, I'd go with a mix of the UV he uses, blue and perhaps some of the white "daylight" (check the specs for the LEDs see which kick out the most towards the blue end of the spectrum)

seezee
1-Mar-2017, 09:47
The UV wavelengths needed to properly expose may be damaging to your subjects' eyes! Better have them sign a waiver if you plan to go that route.

Mark Sawyer
1-Mar-2017, 13:38
The UV wavelengths needed to properly expose may be damaging to your subjects' eyes! Better have them sign a waiver if you plan to go that route.

"The UV wavelengths needed to properly expose" are equivalent to standing in the sun for two seconds (about the normal exposure for an outdoor wet plate portrait). Unless you know something I don't?

seezee
1-Mar-2017, 18:11
"The UV wavelengths needed to properly expose" are equivalent to standing in the sun for two seconds (about the normal exposure for an outdoor wet plate portrait). Unless you know something I don't?

It's not the length of the exposure; it's the intensity of the lights themselves (https://www.aptechnologies.co.uk/uv-led-eye-safety/support/light-emitting-diodes/uv-led-eye-safety) that is problematic. I should have phrased that more precisely.

Mark Sawyer
1-Mar-2017, 18:28
I think it's not so much the intensity of the UV, which would be similar to or less than the sun's. It's the absence of white light to discourage one from staring directly into them. I'd agree with your original assessment, and stay away from LED's for just that reason.

seezee
2-Mar-2017, 17:21
I think it's not so much the intensity of the UV, which would be similar to or less than the sun's. It's the absence of white light to discourage one from staring directly into them. I'd agree with your original assessment, and stay away from LED's for just that reason.

I think you may be onto something. I probably confused the logic for avoiding them, but UV LEDs (and fluorescents) are potentially dangerous to one's health, hence the stern warnings from the manufacturers and the goggles issued at tanning salons.

photojeff3200
2-Mar-2017, 20:10
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.

Mark Sawyer
3-Mar-2017, 11:47
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.

knuf
13-Mar-2017, 14:43
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

chassis
14-Mar-2017, 17:17
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.

janosch simon
15-Mar-2017, 04:53
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

chassis
16-Mar-2017, 08:11
The interest in f/8 and f/11 exposure is more easily attained critical sharpness due to a bit more DOF.

janosch simon
17-Mar-2017, 01:51
hm to me thats the beauty of LF :-) that razor thin DOF :-)

Punker
11-Jun-2018, 15:40
I'm about to start my wet plate journey and have been looking into the LED light issue.

I saw this video on YouTube (https://www.youtube.com/watch?v=2Mc855sJtDA) 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 (https://www.homedepot.com/p/Feit-Electric-300W-Equivalent-Daylight-LED-High-Lumen-Utility-Light-Bulb-C4000-5K-LED/206677057). 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.

179297

cuypers1807
11-Jun-2018, 18:10
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.

3600ws with strobes at 4.5-5.6 is doable with brand new fast chemicals. An aged collodion or tired silver bath extends the exposure needed pretty dramatically. I shoot portraits outside whenever possible.

Joshua Dunn
11-Jun-2018, 19:28
It’s been a few years since I shot wet plate (I miss it) however when I first set up to do portraits in wet plate I bought two large LED lights and it was a pretty miserable experience. They simply don’t put out enough UV light for wet plate. I returned the lights and bought two large flurencent lights and it worked much better. I got my exposures below 20 seconds but it was a lot of light on my models. It was difficult for them to look natural and not squint.

Unfortunately the company that made the ones I bought, Fotodiox, stopped making the ones I bought. But you can see them on this link to Amazon (https://www.amazon.com/gp/product/B0095PO930/ref=oh_aui_search_detailpage?ie=UTF8&psc=1). Maybe that will give you an idea for one to build.

-Joshua

williaty
11-Jun-2018, 21:53
So this thread recapitulates the myth that collodion is primarily UV-sensitive. I think the myth probably is so tenacious because printing processes of the same time period, being mostly iron based, *are* nearly exclusively UV sensitive. I have only seen two rigorous investigations of the spectral sensitivity of collodion, both performed by Mr. Lund. The results varied slightly, most likely because collodion salted with different compounds was used in each test. In one, no meaningful UV sensitivity was observed. The collodion was primarily violet sensitive with some blue sensitivity extending into the low cyan. It was basically "blind" to UV. In the other test, the collodion was most sensitive to deep violet with a small amount of deep blue sensitivity and a meaningful amount of very, VERY near-UV sensitivity.

Taking that small amount of actual objective evidence, choosing a light source for UV is primarily about finding a source with immense output in the violet and very deep blue range. Something with an emission centered on 450nm would be the best compromise between the two different collodions Mr. Lund measured. Thankfully, 450nm extreme deep blue LEDs are easily available. Simply build a light panel, light strip, whatever, out of these specific LEDs and you'll get the shortest exposure times with the least discomfort to your subject of any continuous light source. Because you're only putting electricity towards making exactly the photons the collodion can see, you'll end up using tremendously less power than you would for a wide-spectrum lightsource like a fluorescent or HMI as well as having a lower perceived brightness even though your exposures are much shorter.

Randy Moe
12-Jun-2018, 03:42
Wonít cost much to find out.

I wonder if anybody will try this.

https://www.amazon.com/Led-World-Royal-445-450NM-Power/dp/B01CJM4K4I

williaty
12-Jun-2018, 09:05
Won’t cost much to find out.

I wonder if anybody will try this.

https://www.amazon.com/Led-World-Royal-445-450NM-Power/dp/B01CJM4K4I

On top of the cost of that, you need a hell of a heat sink, a fan to push air through the heat sink, and a power supply/driver. The amazon listing is just for the COB, not a workable system. I did find an eBay auction last night for someone selling all the bits to make a 100W light source at 450nm for around $50, but it's bare bones mad scientist looking stuff. I'd love for someone to spend the money to see if 50W of 450nm is enough to make a plate in a short amount of time.

Randy Moe
12-Jun-2018, 09:12
On top of the cost of that, you need a hell of a heat sink, a fan to push air through the heat sink, and a power supply/driver. The amazon listing is just for the COB, not a workable system. I did find an eBay auction last night for someone selling all the bits to make a 100W light source at 450nm for around $50, but it's bare bones mad scientist looking stuff. I'd love for someone to spend the money to see if 50W of 450nm is enough to make a plate in a short amount of time.

Most likely also need a white light to focus. 500 Watts of LED is overkill. 100 Watts might work.


Everybody here is a Mad Scientist.

goamules
12-Jun-2018, 18:11
Simple wetplate lighting solution: walk outside, set up tripod. (Worked in 1860, works today)

Punker
12-Jun-2018, 18:14
Heheh. True. But not if I want to shoot a still life after work when the sun has gone down.

williaty
12-Jun-2018, 18:25
Simple wetplate lighting solution: walk outside, set up tripod. (Worked in 1860, works today)

Unless it's cloudy

or the model can't show up when the sun is in the right place

or the client asked for a clothing level that might result in a call to the police by the neighbors

or it's cold

or the client wants a background that you can't pull off outdoors


Be serious, there's a reason photo studios exist and why artificial lights exist.

Randy Moe
12-Jun-2018, 18:51
Iím glad you can walk. I like studio work and I can do it even though my body is failing.
I was walking recently, now barely. Iím not overweight, eat right but this last year has been one medical thing after another.

I hope to regain my walk.

Maybe I need a mule!

Iíll check code here. 😜


Simple wetplate lighting solution: walk outside, set up tripod. (Worked in 1860, works today)

cuypers1807
12-Jun-2018, 19:17
Heheh. True. But not if I want to shoot a still life after work when the sun has gone down.
For still life you can just pop a strobe a few times to get exposure. No need for anything fancy.

Punker
13-Jun-2018, 17:59
For still life you can just pop a strobe a few times to get exposure. No need for anything fancy.

I was under the impression you need 3,600+ watt seconds of strobe power. I don't own any proper strobes yet (especially ones that powerful); just hot tungsten movie lights which are poor sources of blue light. Doesn't a speedlight have less than 100ws?

It appears quartz halogen lights have a good spike at the right point in the spectrum too. Still, I think I'll try my hand with a bright cool-white LED which has an almost identical spectral output to deep blue, but is more natural and easy to focus with.

williaty
13-Jun-2018, 18:35
I was under the impression you need 3,600+ watt seconds of strobe power. I don't own any proper strobes yet (especially ones that powerful); just hot tungsten movie lights which are poor sources of blue light. Doesn't a speedlight have less than 100ws?

It appears quartz halogen lights have a good spike at the right point in the spectrum too. Still, I think I'll try my hand with a bright cool-white LED which has an almost identical spectral output to deep blue, but is more natural and easy to focus with.

No, the bright cool white isn't nearly equivalent to 450nm blue. You're wasting a TON of electrons producing photons that the collodion can't seen. Who knows what the ratio is but you could easily be spending 90% of your electrons producing light the collodion can't see. Broad-spectrum LEDs both produce photons the collodion can't see and also have significantly lower luminous efficiencies than monochromatic LEDs do. Both of these hurt you.

FWIW, my friend who got me into this just bought one of the 50W 450nm LED+lens+heatsink kits off eBay. We'll let you know how it goes when it gets here


On the topics of strobes, a lot of people say you need 10kJ to make this work. For whatever reason, I'm doing half-length portraits with just 400J.

Randy Moe
13-Jun-2018, 18:50
Cool! I await results.




No, the bright cool white isn't nearly equivalent to 450nm blue. You're wasting a TON of electrons producing photons that the collodion can't seen. Who knows what the ratio is but you could easily be spending 90% of your electrons producing light the collodion can't see. Broad-spectrum LEDs both produce photons the collodion can't see and also have significantly lower luminous efficiencies than monochromatic LEDs do. Both of these hurt you.

FWIW, my friend who got me into this just bought one of the 50W 450nm LED+lens+heatsink kits off eBay. We'll let you know how it goes when it gets here


On the topics of strobes, a lot of people say you need 10kJ to make this work. For whatever reason, I'm doing half-length portraits with just 400J.

cuypers1807
13-Jun-2018, 20:40
I was under the impression you need 3,600+ watt seconds of strobe power.
3600+ for a one pop exposure. If you are shooting still life you can pop it over and over until you get an exposure built up on the plate. That obviously is not an ideal situation but doable if that is all you have/can afford.

williaty
13-Jun-2018, 22:08
Keep in mind that "pops" are sub-additive. They have reciprocity failure just like any other way of building total exposure. 1 pop is what the meter says. 2 pops is pretty damned close to a full stop above 1 pop. To get the next stop, you typically need 5 pops, not 4. It gets exponentially worse from there. By the time you calculate you need 12 pops... just forget about it.

Punker
14-Jun-2018, 18:00
Found these (https://www.amazon.com/Aquarium-HIGROW-450-460nm-Indoor-Growing/dp/B075RYNP18/ref=sr_1_4?ie=UTF8&qid=1529024261&sr=8-4&keywords=450nm+led&dpID=61p1-9FXghL&preST=_SY300_QL70_&dpSrc=srch) 36-watt 450-60nm blue LED lights. seems promising.

williaty
14-Jun-2018, 18:29
Yeah, those seem like they'd work. No idea how many you'd need though. The only real difference to what I found on ebay is form factor. The eBay light is super industrial/mad hatter while what you found on Amazon is a finished product. You pay slightly more per photon for the nicer product.

Randy Moe
14-Jun-2018, 18:43
I don't shoot wet plate yet! Never say never...

But I found X-Ray film to work without reciprocity failure with 10 additive pops from my Einstein strobes. The math says to use 8 and I give it 2 more. ~20%. Obviously dead life photography.


Keep in mind that "pops" are sub-additive. They have reciprocity failure just like any other way of building total exposure. 1 pop is what the meter says. 2 pops is pretty damned close to a full stop above 1 pop. To get the next stop, you typically need 5 pops, not 4. It gets exponentially worse from there. By the time you calculate you need 12 pops... just forget about it.

williaty
14-Jun-2018, 18:44
Those extra 2 pops are your reciprocity failure. It just means that the x-ray film you're working with has good reciprocity characteristics for strobe bursts. I wonder if that's a trait of all x-ray film?

seezee
15-Jun-2018, 17:21
I don't shoot wet plate yet! Never say never...

But I found X-Ray film to work without reciprocity failure with 10 additive pops from my Einstein strobes. The math says to use 8 and I give it 2 more. ~20%. Obviously dead life photography.

I use Einsteins with x-ray too; they put out plenty of power with a single pop. Why are you using additive pops? I'm confused.

Randy Moe
15-Jun-2018, 17:37
I use Einsteins with x-ray too; they put out plenty of power with a single pop. Why are you using additive pops? I'm confused.

It was 11X14 1-1 Macro still life and that's what my meter told me to do. 610 mm Nikor stopped way down. Maybe all the way. It was years ago and I lose notes.

goamules
15-Jun-2018, 17:44
Unless it's cloudy

or the model can't show up when the sun is in the right place

or the client asked for a clothing level that might result in a call to the police by the neighbors

or it's cold

or the client wants a background that you can't pull off outdoors


Be serious, there's a reason photo studios exist and why artificial lights exist.

Do you shoot wetplate? Do you realize in 1860 photo studios were basically a room with a big skylight. Talk is cheap....shoot some and get back to me and we'll talk.

williaty
15-Jun-2018, 18:02
Do you shoot wetplate? Do you realize in 1860 photo studios were basically a room with a big skylight. Talk is cheap....shoot some and get back to me and we'll talk.

Why are so many people who shoot wet plate arrogant jerks who assume that not one else actually shoots?

Yes, I actually shoot wet plate. I will admit that I can only afford to do it one day a week at this point, but that still means I'm making a couple dozen plates a month. I also realize that daylight studios exist. I don't happen to own one. Nor, in this part of Ohio, would it be a guaranteed success as we have full sun just 67 days a year. High overcast would be fine as well but unfortunately we have a ton of days where the direct sunlight (well, through the clouds, I just mean not in the shade) exposure has gone as long as 45 seconds at f/2.8 for me. That's crap for shooting people.

paulbarden
15-Jun-2018, 19:12
Do you shoot wetplate? Do you realize in 1860 photo studios were basically a room with a big skylight. Talk is cheap....shoot some and get back to me and we'll talk.

Wow, why so rude?

goamules
16-Jun-2018, 05:01
Having a bad day, sorry. But don't like people telling me to 'be serious', when I was being serious. It was offensive, so I came back at him.

koraks
28-Jun-2018, 02:06
3600+ for a one pop exposure. If you are shooting still life you can pop it over and over until you get an exposure built up on the plate. That obviously is not an ideal situation but doable if that is all you have/can afford.
Roughly 4000-4800Ws (additive exposure from 2x200Ws strobes, so possibly limited through reciprocity failure) is what I use for close-lit (1-3ft.) still life collodion negatives at around f/8-f/11 - so with roughly 1 stop loss in bellows extension. Note that negatives require ca. 2 stops more exposure for pleasant tonality than positives. For positives and half-body portraiture, I get away with about 2x200Ws (so two separate strobes) @ f/4.5, strobes at about 3ft, with very little loss in bellows extension (<0.5 stop).

With strobes, things get complicated if (1) you want to stop down to f/8-f/11 or (2) you want to use light modifiers (e.g. softbox) or (3) you want to shoot negatives (like I do) instead of positives. Under these constraints, there's no life below 2000Ws I find.

When working with models, a continuous light source will in my opinion always be problematic when doing wet plate. Best case scenario (LOTS!! of light) you may get your exposures down to a second, which is still long. I'll settle with strobes.

Btw: I checked the spectral sensitivity thing; I took the band gap data of AgBr and AgI (the halides present in a sensitized collodion emulsion) and calculated to which cutoff frequencies they correspond, which are 477nm (AgBr) and 517nm (AgI). This means that a collodion emulsion will not have any sensitivity beyond 517nm (which is in the blue part of the spectrum), corresponding quite nicely with the Lund spectral sensitivity charts available online (specifically this one here (http://www.bordinphotographic.it/spectral-sensitivity-of-collodion/)). The peak sensitivity around 475nm is also explained by these band gaps, as at that point, both AgI and AgBr are responsive.

Now, one might expect that below 475nm the sensitvity should remain high - after all, smaller wavelength photons have higher energies and therefore UV photons should be able to excite AgX grains as well as ones around the optimal wavelength. However, some problems emerge at the lower wavelengths: firstly, energy efficiency decreases - while close to the band gap, essentially all photon energy is used effectively, while at smaller wavelengths, part of the energy of each photon is wasted - excitation of an AgX kernel is essentially a binary thing. Secondly, the smaller the wavelength, the higher the attenuation in a medium. Lund used a prism to create the spectrum used in his test and since a prism is quite a hefty chunk of glass, particularly the lower UV wavelengths will be significantly attenuated before they reach the collodion plate (the same is true for the glass of the lens used). Even window glass (which is only a few mm thick) will block 90% of the radiation below 300nm; a thicker chunk of glass (prism and/or lens) will already significantly attenuate light around 350nm. Additionally, since Lund used a solar spectrum, attenuation of UV by the atmosphere plays a role as well, as much of the UV is blocked, the extent to which depending on atmospheric conditions. This implies that the Lund test is not entirely linear and the response curve is biased by the measurement method.

In conclusion, maximum photon efficiency is achieved around 475nm, which is a deep blue. Sensitivity below this wavelength is essentially the same given the same overall photon flux, but attenuation reduces efficiency as the wavelength gets lower. It would be interesting to test a monochromatic light source around 475nm and one around 400nm (at the edge of UV), both with the same photon flux. The sensitivity should in fact be comparable, as there is no reason to suspect that the sensitivity of collodion would be limited at lower wavelengths. However, there is also no benefit to be expected in using UV vs. deep blue light and overall energy efficiency will in fact be lower.

For practical purposes, this means that for continuous/'hot' lights, a light monochromatic light source of 475nm would be an ideal compromise: it's efficient, doesn't carry the risk of UV damage to subjects/sitters, its light quality can be judged visually and availability of high-power LEDs at this wavelength is good.
For strobes, the situation is a little different, as strobes are of course not monochromatic (discounting pulsed laser); a Xenon flash (unfiltered!) can output a significant part of its energy in the UV spectrum, depending on the power at which is driven and glass envelopes/filtration used (particularly relevant for the sub-350nm spectrum). This means that in a flash exposure on collodion, a significant part of the image is actually formed by UV in addition to the blue light exposure. Due to the short distance, atmospheric attenuation doesn't play an important role as is the case with a solar exposure. The implication is that the quality/nature of the light will be different from a pure blue exposure (as in blue LEDs), and it will also be more unpredictable due to our inability to directly see UV.

TL;DR: blue light at 475nm is ideal, but UV is not wasted on collodion.