Speed difference between Acros II, TMX, and Delta 100 at same CI?

[Stephen Benskin]

Process promptly?

I have several studies that show significant speed differences between fresh exposure and film that has sat for several months between exposure and processing.

The test is straightforward. I put a sensitometric exposure on every other roll of film I roll as I load the cassette.

Then before processing I pull a strip of film from the loader and put a fresh sensitometric exposure on it.

Process in the same tank for the same time, I get two completely different contrast indexes and speeds.

The obvious lesson is: Process promptly.

Then you get the most speed and contrast.

The corollary is: give greater exposure and process to higher contrast index if you feel like you might delay processing.

It's part of latent image keeping. ISO 6 has it in 5.4.1 Conditioning of specimens. "The processing shall be completed in not less than 5 days and not more than 10 days after exposure for general purpose films, and not less than 4 hours and not more than 7 days after exposure for professional films." The old standard had a hold time longer than 2 hours as the effect tends to plateau after a few hours. The standard also stipulates the samples be kept at 23oC +- 2oC at a relative humidity of (50 +- 5)%.

 

[Keith Tapscott.]

Makes sense, Perceptol typically loses a stop in speed, give or take.

He may have gone over to digital imaging now.
I think he used a mamiya rb 67 and a Sinar F 4x5.
The latter he used FP4 Plus at a low ISO rating of around E.I.32-40, again he used diluted Perceptol.

 

[DREW WILEY]

Pan F was designed to accommodate about the same luminance range as color slide film. Yeah, you can tweak the contrast a little during development, but it does best when you seek out subject matter of limited brightness range, or else artificially illuminate it in that manner.

The best developer for Pan F I've used is a special tweak of PMK pyro, rating the film at 25. It's not a particularly versatile film, so I seldom shoot it. But I do have a good number of superb prints made from Pan F 120. It has its own special look.

Acros is quite different, even in spectral sensitivity. Too bad it's no longer available in sheets.

 

[Milpool]

Pan F was designed to accommodate about the same luminance range as color slide film. Yeah, you can tweak the contrast a little during development, but it does best when you seek out subject matter of limited brightness range, or else artificially illuminate it in that manner.

The best developer for Pan F I've used is a special tweak of PMK pyro, rating the film at 25. It's not a particularly versatile film, so I seldom shoot it. But I do have a good number of superb prints made from Pan F 120. It has its own special look.

Acros is quite different, even in spectral sensitivity. Too bad it's no longer available in sheets.

What's your PMK tweak?

I agree Acros sheet film would be a nice option - although I imagine at this point it would be even more expensive than Kodak so perhaps not. For some reason when original Acros was around I never got around to trying it in 4x5. Too bad I missed out. I wonder if the Quickloads worked well.

 

[Stephen Benskin]

Curve shape is also dependent on development. For example, Pan F in Seasoned Xtol, Refrema Dip & Dunk.

Comparing Fan F and Plus-X, CI 0.60. Seasoned Xtol, Refrema. Pan F was shifted to match up the curves at 0.10.

 

[Sal Santamaura]

Reports of Pan F Plus' curve's S-shape and limited luminance range are, in my experience, exaggerated. The below trial (horizontal is Zone, vertical is gross density) was exposed at EI 25, resulted in fb-f of 0.25, EI 25, CI=.50 and Dmax on the fully exposed leader of 1.77. It's got a very shallow toe and shoulder. Extrapolating using the Dmax, it probably wouldn't have run out of steam (while retaining some separation) until near Zone 14, although I only exposed through Zone 10. It's got a very straight line from Zones 3 through 8. I am very pleased with this combination's sharpness and, given how warm our ambient and tap water get here during summer, usability at elevated development temperatures. My results using 120 Pan F Plus in a Mamiya 7 are the same as this trial in a Nikon F6 with confirmed accurate shutter speeds. Both times my Pentax digital spotmeter, recently calibrated by Richard Ritter, agreed perfectly with the in-camera exposure readings.