Help finding a individual post about finding iso/development in 2 rolls.

[cjbecker]

A few weeks ago there was a post about how to find the correct iso and development time for a film in 2 rolls of film. I have search and scrolled for a while now and cant find it. Its killing me that i cant find it. Does anybody remember where it was?

 

[CMoore]

Did you try terms like...
Personal Exposure
Exposure Index
..... stuff like that perhaps.?

 

[MattKing]

Would this post from David Allen be the one you were thinking of?
[URL="https://www.photrio.com/forum/threads/zone-system-find-ei-and-dev-time-without-resorting-to-sensitometry.127180/#post-1680234"]Zone System - Find EI and dev time without resorting to sensitometry[/URL]

 

[Bill Burk]

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)

 

[cjbecker]

Would this post from David Allen be the one you were thinking of?
Zone System - Find EI and dev time without resorting to sensitometry

thats not the post I was thinking of, bit I did bookmark it yesterday!!

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)

Awesome, thanks

 

[bernard_L]

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.

That means gamma 0.5, and therefore C.I. (or G-bar) even less than 0.5. A bit low IMO.

 

[radiant]

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?

 

[Bill Burk]

That means gamma 0.5, and therefore C.I. (or G-bar) even less than 0.5. A bit low IMO.

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.

 

[pentaxuser]

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?

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 N

pentaxuser

 

[MattKing]

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?

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.
You may need a tripod, but low light doesn't preclude a wide range of tones.

 

[john_s]

That means gamma 0.5, and therefore C.I. (or G-bar) even less than 0.5. A bit low IMO.

Maybe a bit low, but very close to what works for me. After years of following the manufacturers' instructions, I finally found how to make better prints, which was more exposure of the film, less development. This is old news today, but before the internet I was a slow learner.

 

[radiant]

That means gamma 0.5, and therefore C.I. (or G-bar) even less than 0.5. A bit low IMO.

I tried to figure this out, but how could you calculate gamma from that Bill Burk's measurement?

 

[Bill Burk]

Two stops is 0.6 log exposure difference. Each stop of light meter needle change is 0.3 (each third stop is 0.1) You just divide one over the other and look for about 0.5.

To be fair, I am rarely satisfied by the two point test. I “need” to see where the curve hits 0.1 above base plus fog and that takes a 21-step test strip.

I just ordered a continuous sensitometry wedge, let’s see if that makes me more pedantic.