UV Film setting experience

[dabateman]

Being initially inspired by this work here:

 

https://www.ultravio...__fromsearch__1

 

And OlDoinyo questions to get below 300 nm first posted here:

 

https://www.ultravio...ch__1#entry5404

 

I was able to figure out a way to adapt my 85mm UAT lens to my Pentacon 6 film camera. Using a macro reverse mount to 67mm, then 67mm to 52 step ring and a 52mm to M42 adapter I can mount the lens. The focus is macro only but works with 6 inch working distance from the front of the lens. Interesting with a M42 to C-mount adapter I was also able to mount the 60mm KSS lens and get a 3 inches of working distance from the front of the lens.

 

But now the hard part. What are the recommended settings and films for UV? As This is shooting blind, and waiting a week to develop it, if I have time.

 

In searching the web and forensics sites it seems people recommend Kodak Tmax 400 as the best film. And what I have found is they say its runs at ISO 10. In a report by Dr. Robin Williams and Gigi Williams entitled "Ultraviolet, Infrared, and fluorescent photography" reprinted from “Medical and Scientific Photography” - An Online Resource For Doctors, Scientists and Students. I was able to find the following spectrum for Tmax 400:

 

They also tested a whole bunch of BW films, from I don't know when (possibly the 1980's) and found that Ilford HP5+ was the fastest, being 4x the speed of TMax 400. However it was not as sharp as TMax and TMax can be pushed. However, I don't believe everything in this study as their plot for available UV from the Sun shows significant amount at 200nm, which isn't true. Unless there was more UVC back in the 1970's and 1980's and recent pollution has blocked it (I am being sarcastic).

 

I do believe this Kodak plot for TMax 400 from 2016:

 

But it cuts off too early to know how good it would be in deep UV.

 

The Ilford HP5plus from 2018 does not look too promising for deep UV imaging:

 

However, most of the film I own is December 2009, expired Kodak Portra NC 160. Its plot from the New formulation (I can't find my NC or VC plots anywhere now) from 2016 is not very encouraging:

 

 

I do have 2 rolls of Kodak TMax 400 Expired August 2010 and two rolls of my favorite black and white film (BW400CN) which is fake BW as you develop it using C-41 chemistry.

But that is not enough for testing and photographing with.

 

So I think I will try to shoot 254nm, 313nm and 365nm Using the 160 Portra. And see how it turns out. I will be at F8 most likely,

 

So does anyone from the old film days recommend what an approximate shutter speed they used to see was?

As in "I would shout outside and it was almost always a second".

 

I did see this Night time thread with B&W shot for 5 minutes:

http://www.ultraviol...oting-at-night/

 

And this discussion on using only Tungsten film, which sadly I don't have:

https://www.ultravio...__fromsearch__1

 

But I don't see any shutter speeds indicated in the last one.

 

I just want to know what to expect to bracket around. I have 13 rolls of the 160 Portra, so shooting a roll with 12 exposures to figure out the exposure is ok. I don't have that ability with my only 2 rolls of Tmax.

 

I am hoping I can see something at 254nm, as that is what the UAT was used with back in the day. But I have been reading that newer films use a UV blocking layer. So that will hurt moving forward.

 

Curious about any suggestions for starting out.

[OlDoinyo]

I will attempt to help as much as I can, but shooting below 300 is a vastly different game than shooting in the 340-400 range, due both to a relative dearth of photons down there and to poorer sensitivity of almost every sensing medium (film or digital.) Also, there is a phenomenon known as skin effect, whereby the shortest wavelengths have trouble penetrating and exposing the full thickness of the emulsion layer, resulting in image attenuation. Moreover, many lenses that are adequate for UVA are utterly useless for the deeper UV, due to sharp cutoffs in the 320-350 range. I myself don't own a single lens that I could use for this purpose, other than my pinhole optic; even the glassless Makowski reflector optic (inexplicably) runs into problems. Thus, my experience may be of limited use to you. I have been thinking along these lines myself, but equipment issues have stymied me. Some general observations, however:

 

-Visible sensitivities of films do not correlate 1:1 with UV sensitivities. The sensitizers in panchromatic film are targeted at the visible spectrum, not the UV; and a "fast" film is only a bit faster than a "slow" film even in UVA.

 

-Don't worry about the tungsten film. It and almost all of the color slide films still made tend to be overcoated, which means that even their UVA performance is horrible. I think tungsten film was mentioned at one point because this type of slide film was one of the last slide films to be marketed without overcoating in the past, but that changed years ago. (Aerochrome 1443 was also never overcoated, because it had no need to be--a #12 filter does not pass UV.) In addition, there are only a handful of places in the US that will still process slide film (I have used Denver Digital recently.)

 

-Color negative films have less of a tendency to be overcoated, but their UV image is a yellow monochrome, which can make the negative hard to eyeball--scanning and pulling the blue channel usually brings it out. Their sensitivity is comparable to that of traditional b&w films. C-41 processing was easy to find up to about 7-8 years ago when all the local drug stores and Wal-Marts junked their film processing departments. Now it is a bit more challenging, but such film gives you the option of mixing regular color and UV on the same roll.

 

 

This was taken handheld with the Olympus 35RD (whose lens transmits down to about 360 nm,) Portra 160VC and a 403 filter. I don't have exact exposure, but it was something like 1/125 second at f/8 or f/11.

 

-Traditional b&w films are not overcoated because serious users of them have almost always used various colored filters, none of which transmit UV; thus, they are one of the more convenient options if you can process them yourself (finding professional labs who will still do this is becoming a losing battle.) In the UVA, they are more sensitive than many digital cameras and allow handheld photography easily as well as photography of moving subject matter. The latest generation of digital cameras operating at gains of 12800 and higher may be starting to challenge them on this front, however. Push-processing is an available trick to gain additional speed, at the price of poorer image resolution and dynamic range.

 

 

This was taken panning, 1/50 second at f/11, on Ilford Delta 3200 through a #403 filter. The camera was a Minolta Autocord whose lens transmits down to approximately 350 nm.

 

 

Same camera and film, with a Baader U2 filter and I think 1/100 second at f/11.

 

 

Olympus 35RD, #403 filter, Tmax 100, 1/125 second at approximately f/11. On the snow at 12,000+ feet for extra UV.

 

You may find it useful to develop a version of "working ISO" or "metering ISO" as a tool to help you if you use daylight as a source. The one relates sensitivity to visible brightness of a scene, whereas the other relates it to a light meter reading through your lens/filter combination.

 

Good luck, and I am curious what filter you intend to try and what subject matter you choose. I have wondered whether lightning or other electrical arcs (from Tesla coils, van de Graff generators, etc.) might emit in this range.

[Stefano]

The cool thing about film is that you usually don’t need a IR-blocking filter. Just a Hoya U-360, for example, is enough.

[dabateman]

OlDoinyo,

Thank you. Much faster shutter speeds than I was imagining. I may just blow 2 rolls and test the full camera range.

For this to be useful for me I want to test 254nm. I can easily image 300nm and up with my Olympus Em1.

So will have to figure out the best subject, that will fit the frame. I will be using my quartz UAT 85mm lens. As I have previously tested all my pentacon six lenses, and none of them transmit down into the UV. Even my single coated 50mm f4 has same response as my multi coated 50mm f4.

 

I have the chemicals to process C41 my self. But haven't in years and to eliminate that variable I found a local professional development place. I thought they were all gone. But living in Washington DC area has that perk, I guess.

 

I have two good filters for 254nm, and will use my 15W 254 ozone free lamps. So should be pushing lots of photons out.

I will post results in the future.