Would this post from David Allen be the one you were thinking of?
Zone System - Find EI and dev time without resorting to sensitometry
Use 2/3 stop less than rated speed. So for 100 film, select 64 Exposure Index on your meter. For 400 film, select 250 EI.
If you want to waste film, take two photographs of a plain surface... one at meter reading and one that's 2 stops greater exposure.
Develop for the time recommended. Hold up the resulting film in front of your meter.
If the meter needle moves 1 f/stop between the two shots... you are done. That's the right development time.
If you don't want to waste film, but are OK making a few prints, just bracket any photograph you are taking with one additional exposure that's 2 stops greater exposure... and print the two different negatives.
If you have to print one twice as long as the other to get the same print... then your film development time is right.
This takes advantage of the fact that most Zone System film speed tests arrive at the conclusion that speed should be 2/3 stop lower than box speed. And that a good contrast to achieve is close to 0.5 (so up in the region of proper exposure two stops exposure difference would cause 1 stop density difference)
That means gamma 0.5, and therefore C.I. (or G-bar) even less than 0.5. A bit low IMO.If you want to waste film, take two photographs of a plain surface... one at meter reading and one that's 2 stops greater exposure.
Develop for the time recommended. Hold up the resulting film in front of your meter.
If the meter needle moves 1 f/stop between the two shots... you are done. That's the right development time.
Sure, you are right it is somewhat low. So, look for between one stop and one and a third stop difference. Effectively it’s a two-point quick and dirty test that lets you catch unexpected results, and the only cost is one or two shots of film. And really, if you wind up bracketing a great shot there’s no cost at all.That means gamma 0.5, and therefore C.I. (or G-bar) even less than 0.5. A bit low IMO.
Hopefully I am wrong but I fear at 61.5 degrees N that you may need to wait for a month or two or longer as you have concluded. I also fear there is no way to replicate the sun indoors for the purposes of the test. Frankly I'd avoid doing the David Allen test even at my latitude in January which is just over 54 degrees NThe David Allen's method is superb, wow.
However could you give tips how to setup a ".. a scene with with a good range of tones". What is the easiest way to achieve this? Finland is currently really dark place, sun barely rises over horizon so no help from sun. Can this achieved indoors with studio flases or how? What is the optimal scene for this kind of testing?
When the sun does peak over the horizon and the sky is clear, take a photo of something that is being lit from the side and has a range of tones itself.The David Allen's method is superb, wow.
However could you give tips how to setup a ".. a scene with with a good range of tones". What is the easiest way to achieve this? Finland is currently really dark place, sun barely rises over horizon so no help from sun. Can this achieved indoors with studio flases or how? What is the optimal scene for this kind of testing?
That means gamma 0.5, and therefore C.I. (or G-bar) even less than 0.5. A bit low IMO.
That means gamma 0.5, and therefore C.I. (or G-bar) even less than 0.5. A bit low IMO.
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?