[UVC SAFETY WARNING] How about trying to record UV-C on film?

[lukaszgryglicki]

[UV SAFETY] UV-C Light Is Dangerous

 

NEVER look at a UV-C light.

NEVER let UV-C light hit your skin or eyes directly or by reflection.

UV-C light can cause:

• severe burns of the eyes and the skin, and
• DNA damage from broken chromosomes.

When working with UV-C illumination, you MUST:

• cover up completely, 
• wear head & eye protection, and
• have strong ventilation.

---

 

While discussing in anothe rthread this idea come to me.

Is it possible to record UV-C on film? Anybody tried?

I mean:

- Nikon F4 + B/W or color or slide film.

- UV-Nikkor.

- 4 x 25W low pressure mercury bulbs (those unprotected generating O3).

- Problem with filtering, I can use Edmund 39319 "FILTER BP 254NM X 10NM UV OD4 50MM" but this is dichroic and very angle dependent - I can see world outside with my own eye, I think it is designed for lasers...

 

My biggest concern would be to guess the exposure needed...

 

[Wayne Harridge]

From what I have read it is best to use b&w film for UV, evidently the dyes in colour film absorb a lot of UV and stop it getting to the silver halide.  I'm not sure how well this will work with UV-C.  Exposure is not really a problem, just use the TTL metering as a first guess and bracket a LOT, then you can work out an effective ISO for whatever film you choose.  I have been thinking of playing with this myself but probably only in UV-A.  I'd be really interested in how you go with this idea.

 

[dabateman]

Yes you can record UVC with film. I even used Kodak porta 400 for a test. But mostly the best signal was all yellow.  So not great. Black and white film would be better.

You can also use Fuji instax, but its all blue if you use color,  so again Black and white is better. Exposure time was in the minutes (10 to 15 minutes).

 

For Portra 400 I needed about 2 to 8 seconds with two 15W UVC bulbs, and UAT lens at F8. 

You could try that to start and bracket around it.

[lukaszgryglicki]

Ok I even have some bw rolls in my fridge.

Thanks!

 

[Wayne Harridge]

23 hours ago, Wayne Harridge said:

From what I have read it is best to use b&w film for UV, evidently the dyes in colour film absorb a lot of UV and stop it getting to the silver halide.  I'm not sure how well this will work with UV-C.  Exposure is not really a problem, just use the TTL metering as a first guess and bracket a LOT, then you can work out an effective ISO for whatever film you choose.  I have been thinking of playing with this myself but probably only in UV-A.  I'd be really interested in how you go with this idea.

 

 

I'm pretty sure this is the article I read:

https://www.medicalphotography.com.au/Article_01/08.html 

 

 

[lukaszgryglicki]

From that articla I see that curves go to log 0 at around 250nm - I'm suspecting that I will record mostly longer mercury lines, not 253.7nm one...

[dabateman]

I don't know where those curves come from. There is no reference.  Kodak only provides data to 350nm.

I am not really a believer in them as I know in a research lab T-max 400 was once used to record x-rays. 

[lukaszgryglicki]

I guess I just need to try and probably ignore most articles, even those focusing on UV - as they are usually only interested in UV-A or at max a bit of UV-B (down to 300nm), everything below 300 seems to be a speculation or interpolation.

 

[OlDoinyo]

Even UVA will give an all-yellow image with Portra. UV does not penetrate to the lower emulsion layers well.

[dabateman]

9 hours ago, OlDoinyo said:

Even UVA will give an all-yellow image with Portra. UV does not penetrate to the lower emulsion layers well.

When I tested it, the UV does go through to even the bottom emulsion.  But they are around two stops different per layer. So you blow out yellow, to get to the lower layers. Which wasn't too bad as you don't easily see yellow. 

But not really worth it,  easily to shot BW or just digital.  Deveping is a pain or expensive.  But one day I might shoot all my film, thats all expired now and develop it in a single shot.

Still just taking up space in my -20C freezer. 

[OlDoinyo]

What gets recorded in the lower layers may not really be UV but rather residual visible leakage, unless your filter stack is very good at excluding that.

 

You can recover a yellow-dye image by scanning and only preserving the blue channel as a monochrome image, or you can just eyeball it through a blue filter if that is too much bother.

[lukaszgryglicki]

Hmm I think using B&W film would be the best option anyway...