Edited by Michael Carter, 06 August 2018 - 09:17 PM.
7222 contact print on PF2
Posted 06 August 2018 - 09:16 PM
Posted 07 August 2018 - 05:50 AM
Edited by Michael Carter, 07 August 2018 - 06:00 AM.
Posted 07 August 2018 - 12:58 PM
You’re doing the right thing, Michael, train your eye and brain on negatives and positives. Not many people are alive who can give you a match. I once met and worked together with a grader, back in the eighties, and he was able to combine Wratten gelatin filters off snippets of a colour negative over a light well. He would look at the image, one hand on the filter drawer, and say 0.025 minus blue, 0.05 minus green. He would then pick a log 0.025 yellow and a log 0.05 magenta filter, punch a compensating circular hole in the Leatheroid band used with an ARRI step printer, and staple the filters over the hole. Whole films were corrected like that.
You might want to make scales, perhaps with a camera. Expose in regular increments, either in intensity or in time, no lens, flashlight onto a white wall. Orwo PF 2 reacts like most other print films with a relative linear response to time differences but towards very short times you will have an ever increasing fall-off. When printing on Orwo TF 12 you will have linear response down to 1/100,000 second and great densities at the same time. I can sell you contact strips of a grey wedge from log 3.0 to 0, one foot long, 35 and 16. Short wedges from log 4.0 to 0.1 are possible in 16.
If you want to upgrade your equipment, let me know about. I sell the most modern film printer light control, Memochrome. With that system you can run up to 32,000 frames at 50 steps per primary colour (RGB), freely programmable. Middle setting is 25-25-25. At 0-0-0 no exposure takes place. As far as I know you have a continuous Uhler. They made step printers also. Some projectors can relatively easily be adapted to printing purposes. I like and appreciate your activity. Do keep going on.
Posted 07 August 2018 - 02:07 PM
Posted 08 August 2018 - 03:46 AM
A grey wedge is a piece of film of continuously varying density. It would take the place of your OOF sky, which of course would only be a single reference point. You would splice it into each printer run and know what density range you were achieving. But you would need a densitometer to get the most out of it.
Edited by Mark Dunn, 08 August 2018 - 03:47 AM.
Posted 10 August 2018 - 12:42 PM
If I can explain something that is complicated as simple as possible, let me try.
The entire calculation of contrast, density, veil, shadows and highlight details, graininess, and whatnot begins with a matte white surface in the dark. Assuming a gain or albedo of 0.9 we have the starting point. From here we go backwards through all conditions right up to camera (shutter open angle, frame rate, film speed, lens aperture (to be quite correct: figure of transmission), filters, and the light on a scene.
Black-and-white positive print film has a gamma of around 2.8 when processed after the recommended formulae and a max. density of around log 3. In other words contrasts up to 1,000 to 1 are transmitted by the print. We want an overall contrast or gamma of 1.5 to 1.6 in the projector which leads us to a negative contrast of 1.55/2.8 = 0.55. The print gamma higher than 1 has to do with the Callier effect of the illumination system of the projector combined with the reflections within the lens. Its value generally lies at around 1.2. Arc lamps are more powerful than incandescent bulbs, 16mm prints therefore are slightly different from 35mm ones. The screen gain influences overall density.
Camera negatives are often developed somewhat harsher than to the 0.55 mentioned above. In turn the prints need to be made a little softer. We can reckon with negative gamma between 0.65 and 0.75. Denser or lighter negatives were religious subjects in the golden age of cinema before the advent of colours. Tastes differ but we can out ourselves as technicians capable of reproducing an image of a scene on a cinema screen at the contrast factor of 1.
Posted 10 August 2018 - 03:29 PM
Posted 14 August 2018 - 01:13 PM
Why not make a WordPress and blog on it. Free and easy. I'd like to see what you have done.
Edited by Daniel D. Teoli Jr., 14 August 2018 - 01:14 PM.