Interesting patent: Camera with reflective film backing plate

[Helge]

Thought someone here might find this as interesting as I did.
https://patents.google.com/patent/US2698561

Had my doubts about the correct forum, but settled on this one.

One way to do a quick hobo version of this involved idea, would be to put some retro reflective material on the pressure plate.
Or paint backing paper with retro reflective paint.
The reflected light would be quite grainy, but would be somewhat compensated for by the initial light.
You could approximately double the real sensitivity of any film where the anti halation is removable (cine film and most black and white film).
And of course get a wonderful HIE aura effect.

 

[AgX]

A reflective pressure plate we disccussed here in the past.

The important point with this idea is that in effect a concave mirror of apt focal length is applied.

 

[AgX]

And not only apt, but even adaptable.

 

[Helge]

A reflective pressure plate we disccussed here in the past.

The important point with this idea is that in effect a concave mirror of apt focal length is applied.

I know. Hence the “hobo”.

 

[AgX]

Maybe we should start a forum "Failed Patents".

 

[Helge]

Maybe we should start a forum "Failed Patents".

That’s actually a great idea.
Could be called “Half baked ideas and forgotten patents”.

That, as well as a book sub-forum.
Both for photo books, technical and “other”.

WRT the original idea here, you’d really need to also follow the focus, for the optimal result, and not just focal length (since focus is just minuscule changes in focal length).
Would be very doable today with a Mylar or other flexible plastic mirror.

Also, since this technique roughly doubles the speed, you could also do dichroic colour separation on B&W with little loss in speed.

 

[samcomet]

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!

 

[Helge]

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.

 

[gone]

Stanley Kubrick was a once in a lifetime genius. He did what others only dreamed about.

On 20001: A Space Odyssey, he wanted the best background photos he could get for the sunset shots, so he dispatched several teams to countries and filmed things at sunset and sunrise w/ 8x10 cameras and slide film. After a few months they returned, and he had to build his own projector to use the huge slides, and also had to design and build a cooling system because the high heat from the lamps were melting the slides.

That worked OK, but then he was having trouble getting enough light to photograph both the actors in front of the projected image, and the projected images too. So he went to N.A.S.A and found some, literally, space age Mylar type of film that had amazing reflective properties. Unfortunately, the camera was picking up the seams where they had to join the reflective material, so he had the crew tear all the Mylar into tiny pieces, then glue them back together in random patterns. After that, the camera didn't "see" the seams.

What he didn't know about light and photography, didn't exist.

 

[Helge]

Stanley Kubrick was a once in a lifetime genius. He did what others only dreamed about.

On 20001: A Space Odyssey, he wanted the best background photos he could get for the sunset shots, so he dispatched several teams to countries and filmed things at sunset and sunrise w/ 8x10 cameras and slide film. After a few months they returned, and he had to build his own projector to use the huge slides, and also had to design and build a cooling system because the high heat from the lamps were melting the slides.

That worked OK, but then he was having trouble getting enough light to photograph both the actors in front of the projected image, and the projected images too. So he went to N.A.S.A and found some, literally, space age Mylar type of film that had amazing reflective properties. Unfortunately, the camera was picking up the seams where they had to join the reflective material, so he had the crew tear all the Mylar into tiny pieces, then glue them back together in random patterns. After that, the camera didn't "see" the seams.

What he didn't know about light and photography, didn't exist.

The Mylar was 3M RR material.
Interesting story about the Dawn of Man sequence.
Regular patterns is never a good idea. The human visual system is extremely good at picking up on them.

Look at the leopard in one of the scenes in the sequence. It’s eyes have retro reflection too from the projected image.

The pinnacle of retro reflective front projection was the Zoptic system first used in Superman the Movie. It actually shares some ideas with the idea discussed in the patent.

 

[Bill Burk]

Not a failed idea at all.

The reflective backside is how Polaroid achieved 1000 speed film. Since you were making a positive, the back didn’t matter. Since you weren’t enlarging, the problem of grain and sharpness weren’t a deal breaker.

 

[samcomet]

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?
[trimmed]
G'day Helge,

It certainly was American Cinematographer but as I remember, those stories about "....how I shot [insert film name]..." usually came out within a few months of the theatrical release date, so to find the article it may very well be an easy net search for the date and then head to an archive or library. Being retired now from the film industry I also "retired" all my AC magazines to a local library. Best of luck & cheers! Sam

 

[AgX]

Not a failed idea at all.

The reflective backside is how Polaroid achieved 1000 speed film. Since you were making a positive, the back didn’t matter. Since you weren’t enlarging, the problem of grain and sharpness weren’t a deal breaker.

Never a concave mirror was employed for backlighting a film.

 

[Helge]

Thank you Sam!

Not a failed idea at all.

The reflective backside is how Polaroid achieved 1000 speed film. Since you were making a positive, the back didn’t matter. Since you weren’t enlarging, the problem of grain and sharpness weren’t a deal breaker.

Never a concave mirror was employed for backlighting a film.

No, but the film was exposed from the back with a folded optical line, involving a mirror.

Never new about the mirror back on the 1000 film.
Makes me wonder if it would be possible to replace anti halation dye on the back of at least B&W film with a something reflective and easily removable with a pre wash. Might give us very high speed film for little RnD investment.