Rollei Pan 25 as Neg and Pos at same time

[Tim Povlick]

I just shot some Rollei Pan 25 and developed as follows:

5 minute pre-soak
12 minutes in 1 + 4 Rollei RLS developer
30 sec wash in water
2 minutes Kodak Rapid Fixer
Water wash

The negatives are a bit thin / low contrast but probably scan-able. When viewed via a back light they look like a negative. When the viewing light is overhead, over the shoulder say, the film now looks like a darned good positive. Is this the way Pan 25 behaves.

Can one use other developers such as TFX2 / HC-110 / Pyro with this film? I tried TFX2 and got a nice clear piece of Mylar for my troubles.

Thanks,


_ .. --
Tim

[Arne Croell]

That effect is not specific for Rolleipan 25, although more common with low sensitivity film. The type of illumination where you see it as a positive is essentially a "Dark Field" (DF) illumination (common in microscopy) and happens when the negatives are too thin (underdeveloped and underexposed). The positive image is due to the silver crystals reflecting/scattering light back to your eyes, and can be enhanced when viewed against a black background (black velvet) with oblique lighting from the sides. This used to be the only way to salvage negatives that were too thin to be intensified, by rephotography in a a DF illumination setup.

[mcfactor]

Yes, it is. For some reason, with this film, at certain angles it looks positive. I have used rodinal 1:100, Beutlers 1:1:10, and pyrocat-HD 1:1:100 and they have all given me excellent results.

[domaz]

All my underexposed (or even slightly thin) Pyrocat negatives have that effect. All meaning FP4 and Delta 100 mainly.

[Tim Povlick]

Very interesting as I had not noticed this before. I'll have to dig out some other thin negs and see if the effect is present. Thanks Arne for explaining the science behind it, so to speak :-)

For a challenge I'll try scanning some and see what happens. The problem is why did this occur, but I will try to work that out.

Thanks Mcfactor for the information on other developers. This really helps as I am out of RLS and don't want to buy more. Will try the Pyro-HD.

Thanks Arne, Domaz and McFactor for your time and expertise.

Best Regards,

Tim

[Jim Noel]

During WWII when the only 35 mm film I could get was DuPont Superior No. 2, Weston Speed 50, most of my negatives had this capability.
I loved it. I could judge an image by looking at the positive prior to printing. They printed beautifully, and I still have some of them.

[mcfactor]

No problem, I just started to use Pyrocat-hd and I am very impressed with the results. The negs dont necessarily look sharper than with the other developers I listed, but it looks like there is more detail (it is hard to describe).

[Tim Povlick]

During WWII when the only 35 mm film I could get was DuPont Superior No. 2, Weston Speed 50, most of my negatives had this capability.
I loved it. I could judge an image by looking at the positive prior to printing. They printed beautifully, and I still have some of them.

Hi Jim,

Well I think the 40's and 50's were the golden years for photography (minus WW-II years or course) although I was a young pup and missed it, hit the 60's instead. I didn't even know DuPont made film.

I sure agree that the positives look great. I am trying to think of a way to front light them with LED's or something like that to make use of this property.

I'll give them a try with contact printing then.

Thanks & Regards,

Tim

[Tim Povlick]

No problem, I just started to use Pyrocat-hd and I am very impressed with the results. The negs dont necessarily look sharper than with the other developers I listed, but it looks like there is more detail (it is hard to describe).

I have used it several times now and echo your sentiments. Maybe more "tonality" and better 3-D effect is a way to describe it.

Best Regards,

Tim