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Any film w/ no anti-halation backing? I need a clear film... tapetum lucidum

holmburgers

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Ok, what I'm looking for is a film that can let light thru it before processing. Most films look completely opaque to me, but are there any of the older style films, or perhaps the IR820 Aura that are more translucent before processing??

Oh yeah, you're probably wondering WHY I might want something like this. Well it's because I want to try out a theory....

First, the primer. So the 'tapetum lucidum' is the reflective layer behind the photoreceptors in many different mammals' eyes. It is what causes the eyes of cats, deer, lemurs, etcetera, to shine brightly when hit w/ your headlights for instance. It helps them see in the dark by bouncing the incoming light back into the rods/cones & thus giving it several chances of hitting a photoreceptor.

With this in mind I started thinking about how to apply this photographically, to increase the possibilities of low light picture taking. My idea is to swap the black pressure-plate with a mirror. IF some light could make it thru the film and bounce off the mirror back into the film then you would effectively raise the speed of your film/lens setup. It also might look really cool.

So basically, is there any film that would allow light (even a bit) to travel thru it? Or perhaps a film whose anti-halation backing can be removed? This is a consideration for some DIY autochromists, as seen here... (there was a url link here which no longer exists) *Talking about removing the anti-halation backing in an alkaline solution.

Thanks in advance for any help and insight, and no thanks in advance for anyone who thinks this idea is just plain stupid.
 
Well, to start with, an emulsion itself is rather opaque and has a color about like butter. In fact, a chunk of film emulsion is kind of like a pat of butter. Ortho sensitive emulsions are reddish yellow and pan emulsions are dark gray and just about as opaque. The emulsion has up to 3 dyes on it for light sensitivity, then it has acutance and trimmer dyes dissolved in it before coating. These adjust sharpness and speed. Behind the emulsion is the antihalation layer that is the part that mainly concerns you. It is there to prevent what you are trying.

If you allow this back reflection to take place, you get a very strange appearing photo. Some like it and some do not.

I have no help to give, but I hope this explains what you observe in film.

PE
 
So without the AH layer, there would be some translucence?

This is helpful, thanks very much!

C.H.
 
Yes, the film would be a milky gray or reddish orange depending on spectral sensitivity (pan or ortho).

PE
 
X-ray film has emulsion coated on both sides. It comes in sheets starting at 8x10. It is mucho cheap for experimenting. It's easily cut into 4x5 sheets making it even cheaper. It would be easy to place a reflective material like metalized mylar in a film holder for your experiment.
 
Wayne;

Ever see an X-Ray? It is blue or blue gray in color due to the dyes added to the support. In addition to that, the heavy emulsion layer makes it nearly opaque to visible light. The X-rays and the fluorescent screen behind it do the imaging.

PE
 
The AH layer is water soluble, and comes off in the presoak, turning the water blue (for common Kodak and Ilford sheet film). So just soak film & let dry before exposure. There will be noticeable 'hazing' surrounding pinpoint light sources & bright doorway boundaries and suchlike. Good for pictorialist imagery. A reflective pressure plate or holder would certainly boost this effect, I would imagine.

Whatever you do...do side-by-side test exposures with and without AH layer, and post the results!
 
If the emulsion is closest to the lens, the image will be less sharp due to the fact that the reflection of the image is farther away by twice the film backing's thickness. If you start with the emulsion next to a first surface mirror in place of the back plate, standing waves will be formed in the emulsion when the reflected image interacts with the incoming image. If the grain of the emulsion is fine enough to resolve these standing waves, you can get a reflective color image from the developed image. There are lots of ways this might not work, and only one way it might work, and that way causes a loss of film speed.
 
P.S.
many films, IIRC, have some small density in the base to prevent light piping. Fix and wash a short piece of unexposedd film and measure its density to find out. Remember that the image light passes through this base twice when you use a mirror for a backplate
 
Kodak Aero-duplicating film has no AH backing, is ULTRA fine, blue sensitive and extremely SLOW (iso .5?) Can sometimes be found on eBay.
 
read the data sheets for...

ILFORD delta 100 & 400 in 35mm only

ILFORD delta 3200 in 35mm and 120

ILFORD PAN F Plus in 35mm only

ILFORD FP4 Plus in 35mm only

ILFORD HP5 Plus in 35mm only

ILFORD XP2 SUPER in 35mm only

ILFORD SFX 200 35mm and 120, grey acetate base
gives good halation protection

these ILFORD FILMS do not specifically mention anti-halation backing

that wasn't so hard now, was it??

perhaps ask Simon R Galley
 
Denis R said:
these ILFORD FILMS do not specifically mention anti-halation backing
Click to expand...

Yes but they all have antihalation layer, like all usable films have. The "anti-halation" name suggests why.

I happen to have a roll of some EFKE 25 that doesn't seem to have proper antihalo layer. It's quite translucent.

And yes I believe that some photographic speed can be obtained by using white paper or a mirror behind the film if it doesn't have any antihalo layer, but there is a huge trade-off in sharpness and of course the halo effect. Maybe you can get an extra stop?
 
It sounds like you could do with a material like a photochromic (reactolite) lens that stays permenantly darkened when exposed to light. Don't the nuclear industry IIRC use crystals that do something similar under bombardment from radiation?
 
As hrst indicated there are several means to conquer halation:
-) reduction of base thickness (glass to film)
-) AH backing layer
-) tinted base
-) AH sublayer
 
Anyone who's ever loaded a sheet of film into a holder backwards will be able to tell you that while the film may appear completely opaque, it's not. I've done this in error more than once or twice with a couple of different films. Even without something highly reflective behind the film, I did get an image. Sharpness suffered, and the negatives were underexposed by at least a full stop; but it's obvious that some light got through. So yeah, I'd say give it a shot. What have you got to loose? I think a piece of undeveloped and fixed out piece of glossy RC paper might make a good enough reflective backing for what you want to do. If you're looking for normal sharpness and resolution, well, that's not going to happen. Could be an interesting look with the right subject though.
 
All the antihalo stuff in any decent film will drop more than one stop, maybe 2-3, some sources mention 5 stops. The light also has to pass two times through the layers (this is not true when accidentally exposing thru the base), so even if it was only one stop, you could only obtain max 1/3 stop speed increase in the best case. If the drop is 2 stops, you get 1/12 stop in the best case. That's the idea of antihalo. I'm sorry to say this but I believe that the emulsion has to be coated on reflective surface, or you have to find a film completely without any antihalation layers, base dyes or backings. And I didn't even include the light loss in the emulsion layer itself in the previous figures.
 
Efke IR 820C Aura shot unfiltered as a 100-speed film is what I would suggest. Treated this way, it will act like a standard b/w film. The drawback is that it is rather expensive at ten bucks a roll, and also rather damage and defect prone IME. Also, the finish work on the base material always seems to be of low quality. I always have regular patterns in my base material (swirls). Same with all Efke films. I really love the emulsions they use, but their quality is just crap IME. I had a 35mm cassette pop open on me when I dropped it one time. Worst, most crummy, jaggedy-edged, cheaply-felted, held-together-by-spit-and-a-prayer 35mm cassettes I have ever seen. I have had an Ilford cassete tumble 50 feet down a concrete embankment and be totally fine, but I drop an Efke cassette onto the bathroom sink, and the roll is ruined. The only reason I use these films is for their uniqueness. I wish they would get their quality together. I ALWAYS make SEVERAL backup (duplicate, not bracketed) exposures when shooting Efke films, guided by these bad experiences. This usually saves my ass by giving me at least one undamaged, printable neg, but makes shooting the film even more exorbitantly expensive.
 
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I don't know for sure, but rumor hath it that PolyPan F has no AH backing. Said to be so because it's primary use is a movie print film. Just mention it.
Price is right too - comes in 90 m rolls.
Murray
 
Murray Kelly said:
I don't know for sure, but rumor hath it that PolyPan F has no AH backing. Said to be so because it's primary use is a movie print film. Just mention it.
Price is right too - comes in 90 m rolls.
Murray
Click to expand...

If it is a usable movie print film, it definitely has AH dye layer, because sharpness is crucial in movie prints. At least color print films have.
 
hrst, that was what made me reply on Murray. But he has it about AH backing. And you don't find that cine print films. So I deleted my reply...
 
Yeah, but for intended use it's an equal problem.
 
It might be enlightening to temporarily place a second sheet of of regular film between your target film stock and the pressure plate and and develop both sheets as a diagnostic to see how much light is getting through your target film stock (i.e. the film stock you intend to use with a mirror).

Your project sounds interesting, if for no other reason than to see what effect you end up with.

Denis K
 
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