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Light with orthochromatic emulsions

Yaeli

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Jun 2, 2021
Messages
173
Location
France
Format
35mm
Hello everyone,

So, I've decided to try using direct positive paper (and maybe later, if I feel comfortable enough and crazy enough, dry or wet plates). I understand that exposing such medium is a bit tricky because it mostly reacts to UV and blue light, and therefore a lightmeter is of little use (unless you do a test plate and check the EI to reuse that). I've seen plenty of videos where people just blast super powerful strobes in people's faces and blind them for an hour, but I'm not really interested in doing that. So I was wondering : isn't it possible to use UV lights instead and figure out a correct, reliable and easily "replicable" exposure for portraits, indoors or outdoors ? There are small, portable units or even bulbs that do UV light. Can't they be used and set up at a certain distance in order to obtain a "fixed" exposure that you can easily reuse anywhere ? Wouldn't that be simpler and more effective than powerful strobes ? And if so, why I have never seen anyone using that ?
Also, I was wondering : can you place a blue filter, like a 47B, or a dark blue filter on top of your lightmeter to cut out the red light and obtain a decent reading for orthochromatic emulsions ? I have never seen anyone doing that either, so I'm wondering if it's doable or not.

Thank you beforehand for your answers !
Sincerely,
Yael.
 
UV light can damage eyes if you aren't careful with the more intense sources.
And it will also cause sunburns too
 
MattKing said:
UV light can damage eyes if you aren't careful with the more intense sources.
And it will also cause sunburns too
Click to expand...

You're right, but I thought it would be ok if : 1) the light was higher than the eyes, and at an angle 2) the light was a 395nm and not 365nm (which are more dangerous, apparently) 3) there was some kind of diffusion on the light. Especially considering that it would only be for a few seconds for the exposure.
 
Yaeli said:
I understand that exposing such medium is a bit tricky because it mostly reacts to UV and blue light
Click to expand...

Which paper are we taking about? This is the spectral sensitivity for e.g. Harman Direct Positive:

As you can see, it's orthochromatic and even almost panchromatic with sensitivity extending to ca. 625nm (orange-red).
Sensitivity to UV is actually quite limited, so you're much better of exposing this paper with visible light.

Yaeli said:
isn't it possible to use UV lights instead and figure out a correct, reliable and easily "replicable" exposure for portraits, indoors or outdoors ?
Click to expand...
NOT a good idea. The problem with UV is that the tissues in the eye are indeed easily damaged by UV radiation, and as regards the retina and tissues immediately behind it, this problem is exacerbated by the pupil not responding to (invisible) UV light. Hence, more potentially damaging light is actually passed through the eye to the retina and its connective tissue. For the cornea it of course doesn't matter; this will be blasted anyway.

While longer UV wavelengths will indeed be less damaging than shorter ones, and incidental (as opposed to repeated) short duration exposures will likely not pose a significant threat, I don't see why you would go here.

For wet plate / collodion it's a little different since that really is virtually only sensitive to UV, so you basically have little choice but to rely on it, either in the form of strobes or in the form of sunlight. I'm not aware of anyone having tried blasting portrait subjects with intense UV radiation for that purpose, although I'm sure someone must have attempted it at some point. Still, I'd not recommend it.

In short, if you were to attempt something along these lines, it would probably not help all that much for what you're trying to accomplish, and it does carry risks although you'll likely get away with it. I wouldn't do it and just do the sensible thing: verify the spectral sensitivity of the paper and optimize for that.

Also, your portrait subjects may not like being photographed with only blue or UV light as it makes people look 'funny'. It's a bit of a trope, but it may work OK for the old man with the wrinkled face; many people still don't like to see themselves like this as it very strongly emphasizes blemishes on the skin etc.
 

Thank you so much for your very detailed answer !! I really, really appreciate it !
I don't know why I was under the impression that direct positive paper was mostly sensitive to UV and blue light... I must have confused with collodion and bunched the two together. You just spared me a ton of trouble ! Thank you so much !
Thank you for the details concerning UV light too, and the risks.
As for people looking "funny", those blemishes and redness of the skin would appear very prominent with collodion, wouldn't they ? It's part of the look, if I'm not mistaken. But you're right, I'm not ready for that yet anyway, so DPP is already plenty enough of a challenge for now
Again, I can't tell you how grateful I am. Thank you !
 
Yaeli said:
As for people looking "funny", those blemishes and redness of the skin would appear very prominent with collodion, wouldn't they ? It's part of the look, if I'm not mistaken.
Click to expand...
Yes, that's right; one more thing that tends to happen is if people wear regular glasses, they generally go dark as if they're dark sunglasses because of the UV coating on the glasses.

Collodion is fun; I've never shot DPP but have on rare occasions reversal processed regular film or paper. There's so much to explore! Don't forget to have fun!
 
koraks said:
Yes, that's right; one more thing that tends to happen is if people wear regular glasses, they generally go dark as if they're dark sunglasses because of the UV coating on the glasses.
Click to expand...

Many years ago I attended a meeting of the Northwest Alternative Photography group in Bellingham Washington where we enjoyed a demonstration by a wet plate photographer who worked out of a small, old style travel trailer.
The group portrait she took of all of us was funny - so many of us traditional process photography fans wore glasses, and therefore sported hidden eyes!
 

That's good to know, thank you !!

There is a lot to explore indeed ! I'm going to start with the Instax back, so I can see the results easily, and it doesn't cost me too much when I mess up (which I surely will). Then I'll move to DPP, which is still reasonable in terms of price. Then maybe B&W sheet film and contact printing. And then, if I have gone that far without turning insane or discouraged, I might try collodion... The road ahead is long and arduous
 
If cost is a factor, try regular paper negatives. Buy a box of Fomaspeed RC paper, cut it to fit into 4x5" holders and happily shoot away. Develop them as negatives and scan or even just photograph with your phone, and invert with e.g. Snapseed.
 
koraks said:
If cost is a factor, try regular paper negatives. Buy a box of Fomaspeed RC paper, cut it to fit into 4x5" holders and happily shoot away. Develop them as negatives and scan or even just photograph with your phone, and invert with e.g. Snapseed.
Click to expand...

That is indeed quite cheap, but I wanted to avoid a "digital step" in the middle. Which is why I went for direct positive paper. I also thought about using Foma 100 and Foma paper for contact prints, which brings the cost to around 1.3 euros per image, so significantly cheaper than direct positive paper.
 
koraks said:
You can contact print the paper negatives. All analog, very affordable, not very difficult and fun to do!


That works great as well.
Click to expand...

I had not thought about that ! Thank you
 
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