I may have already discussed this, somewhere here a long time ago but after reading an article about Stanley Kubrick's cinematographer, John Alcott, and his shooting of Barry Lyndon, I did this very same thing. According to the article, apart from designing and building a new type of lens to shoot the film under candle light, they removed the anti-halation layer from the film prior to shooting. They then used the reflective pressure plate to achieve halo effects from the candle lit scenes. I did something similar after reading this article and had a pressure plate from a no-longer-used Fujica ST901 silver plated and shot a whole series landscapes and night street shots this way on 35mm B & W stock. I must say in hindsight it did in fact work a treat, but it did not really give me an effective increase in film speed, only an interesting "look." It reminded me of primitive old time lenses and early photographic look from the pastoralists. I must admit that while it was an interesting thing to do I much preferred the sharp "straight" look of a modern lens for my night street photography. FWIW Cheers!
Thanks for the comment Sam!
Never knew that fact about the cinematography of BL. Very interesting.
Would you happen to remember in what publication you read the article, and what number/date? American Cinematographer?
I too have experimented with washing off the AH dye.
In my case Aviphot for IR shooting. And even, in a primitive crude way, tried putting some squares of tinfoil between the backing paper and film to see the effect.
I can only say it achieved exactly what I thought it would.
IE a marked increase in speed. A little under one stop for just washing (my guess as I don’t have a good way of measuring density). And perhaps a little under two stops for both.
So going from a speed of about EI 12 to being able to get at good image a little shy of EI 50.
And of course some haloing. Though surprisingly discreet in 645 format.
One nice benefit with Aviphot is that it lowers contrast markedly. Much like flashing.
Washing off AH dye is not that hard if you have a darkroom.
Just be very careful to not touch the film recording area, and dry it completely and evenly before rolling it up again.
A quick post wash with alcohol can help.
The big difference with the above Patent is of course that it aims at refocusing the image back on the film from the back.
A simple mirror will always get a lot of halos and blooming because the reflection is not direct or colaminated and the emulsion doesn’t touch completely or evenly all over.
A retro reflector very close to the emulsion might be better, but will AFAIK always have grain.
The best solution would be an aspherical mirror.
For ultimate resolution no back reflection will always be preferable. But for a lot of scenarios this could actually be a good compromise.