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tom.w.bn

Behind the film - Inside the Ilford factory

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vor 1 Stunde schrieb adan:

Simple question - why would anyone want to use Pan F+ in sheet film sizes?

In 35mm, the fine grain makes a difference.

PanF+ has a special contrasty look, that's why most people use it, not because it's a super fine grain film.

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17 minutes ago, tom.w.bn said:

What conspiracy theories?

It was a light hearted comment, but I was referring to the various claims about keeping properties etc. People always try to read into things perceived hidden "facts". 

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On ‎7‎/‎12‎/‎2019 at 10:53 PM, pico said:

Interesting observation. Thanks. I wonder what that means to us as users. Does the film rapidly deteriorate? We should know.

No it doesn't rapidly deteriorate. I came across a roll of 120 Pan F that had been in a little used camera for over two years and it developed perfectly.

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22 minutes ago, tom.w.bn said:

In the PanF+ technical information, Ilford recommends to develop the film within 3 months after exposure.

Yes, it actually says as soon as practically possible and ideally within 3 months, which is a common sense approach but the film that I processed was also out of date. I am sure that if examined closely there would have been some deterioration but not enough to notice. Most slow speed films are more at risk from lengthy storage after exposure and normally a film should be processed within days in my view. I aim to process within that time frame anyway. However some time ago I processed a film that had been in a camera since the 1960s (not Pan F, it was Kodak Verichrome Pan) and the result was passable, just.

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When you expose film, you produce a latent image. Very approximately, the incoming light photons knock loose silver ions (pure silver) from the silver-halide crystals, and those then get trapped within the crystals to form "seeds" that development can amplify about 1 billion times.

Slower films, and/or finer grain, and/or cubic crystals (old-school, vs the T/Delta grains) apparently provide fewer or less-firm "traps" for those ions, thus the latent image is inherently a bit less stable - the ions (atoms minus or plus one electron) would really like to combine with some other atom to share electrons, and thus "disappear" as pure silver, over time.

That explains why Ilford is a bit more - definite - about post-exposure keeping times for Pan F. It may not be the best film to take on a 6-month trek through Africa before processing. But I'm not sure any film is ideal for that - Nat. Geo photographers on long projects generally shipped their film back weekly (by canoe, if needed) to avoid it sitting unprocessed too long. OTOH, we're all familiar with the "two Christmases on the same roll" phenomenon. Ultimately photography depends on quantum physics (Heisenberg, Schrödinger, "playing dice with the Universe," etc.), so you just never know.

As to Pan F's "special contrasty look" - actually I used it because it had a l-o-o-n-g tonal range, as well as grain below the threshold for "grain aliasing". Whites that went on forever. But I was shooting and processing for scanning, and using nice gentle Mandler lenses. Attached is Pan F exposed via M6 meter at EI 64-80, 21mm Elmarit pre-ASPH, and developed at 15% less than "box time" in Ilford DD-X. Scanned on Nikon Coolscan 2, 2003.

The underexposure and underdevelopment pulled the highlight densities down out of the stratosphere, while the scanner dug out every bit of shadow detail.

Edited by adan

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On ‎7‎/‎14‎/‎2019 at 2:22 AM, adan said:

Simple question - why would anyone want to use Pan F+ in sheet film sizes?

In 35mm, the fine grain makes a difference (I used it religiously in my Leica/scanned-film days 2001-2004) - but from 4x5, you'd have to make prints the size of billboards to see the difference (if any) between Pan F and Delta 100/Tmax 100. Which is why Kodak dropped their equivalent Panatomic-X decades ago (in all sizes) - Tmax 100 made it superfluous.

Given that 4x5 format has (and often needs, for DoF) lenses going to f/64 - I'd want that extra stop of speed.

Corollary question - if there aren't a lot of responses to that first question, how economical is it for Ilford to coat the separate, heavier, sheet-film stock with Pan F emulsion? Can they sell one batch of 4x5 (let us say, 10,000 boxes of 25 sheets each) in the 2-4 years before it expires? How much would this small company have to throw away?

I would love to use PanF+ in 4x5" size. Why? Because IMO this film has the best greyscale latitude of B&W films which I have tested so far. My second choice would be FP4+ but not Delta 100. Even TMax100 is a great film, too - but it is by far not the same as PanF+ from my experience. I don't care about the speed when using PanF+ film - most often I shoot on a tripod with longer exposure times anyway. 

You might not see a purpose of using PanF+  in sheets but this doesn't mean that other photographers think alike. What I was reading and watching on other related YouTube videos where this was discussed it is more of a technical issue why PanF+ doesn't exist as sheet film. But details of why exactly were never mentioned anywhere to my knowledge. 

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