What factors affect grain?

It's interesting how tenacious some things are in photography. "ASA" - the American Standards Association is no more - it was replaced by "ANSI" - the American National Standards Institute", some time around 1970 - 1973 ~ 30 years ago, or so.
ANSI, itself is no more - everything went to ISO - not sure of the acronym, but something like "International Standards Organization" .. some time in the early '90's
Interesting - how we cling to "ASA". The only place I see it mentioned now is in reference to film speed. It is correctly, "ISO"... lest someone starting out become confused.

Yes, and ISO is the manufacturers recommended/tested speed under very tightly controlled circumstances. EI(exposure index) is what the individual needs to determine for their own specific circumstances. When you change developer/meter/camera/etc. you also need to retest to determine the new EI(PEI)

Ei EI Ei O ?
Sorry couldn't resist...

'ANSI, itself is no more'

ANSI still exists, and it is responsible for a number of photographic ISOs, including the ones on the required purity of chemicals for photo use. It is reassuring to know that the purity of our vital fluids is controlled by the free world.

Best,
Helen

Be sure to do testing with Tri-X!!! I used to shoot Tri-x at 250 but when i finally got around to doing real testing, Zone I landed on ISO 160 !!! This was confirmed by my mentor as well - "yes, I thought I'd let you figure that out for yourself" was his response (bastard! hehe). But then again, Tri-X was never "fine grain" to begin with. And is very prone to reticulation. TMax films are more resistant to reticulation. As for developer effecting Exposure Index, for normal development you should only get ONE exposure index in accordance to your combination of equipment, developer, dilution choice. When you do an N+1 then sure, you'll get a 1/3 stop change in EI for the increased density - so rate it 1/3 stops faster. For practical use, agitation method will not change your EI significantly enough to scream bloody murder. Developer dilution will though! The higher the dilution, the higher the compensating development occurs thus lowering ISO speed.

And yes, Mike is right.. If you don't do the proper testing, all it is is guesswork.

Attached are some Tri-X from 35mm.

Helen B said:

'ANSI, itself is no more'

ANSI still exists, and it is responsible for a number of photographic ISOs, including the ones on the required purity of chemicals for photo use. It is reassuring to know that the purity of our vital fluids is controlled by the free world.

Click to expand...

Hah!!! I stand corrected. I just visited that site. It doesn't look a lot like the old ANSI that I knew, but you are right ... it still DOES exist!

I'll have to search further ... I tried entering "Film Speed" and a couple of permutations of that ... with no success.

Interesting. THANKS!

It's covered by the ISO standard. Here's the B&W one.

Best,
Helen

bjorke said:

Digital ICE etc, do not function on B&W films like Tri-X. XP-2, yes. FP4, no.

Click to expand...

Oops, you're quite right. David.

Before you do any testing or rating of the film you might want to get your camera(s) checked and calibrated, especially if you are using the onboard meter. It's meaningless to rate a film if your shutter speeds and meter are not calibrated. This should be the first step.

The film testing puts that inconsistancy into account. A lot of hardcore large format photographers I know do density testing for every lens' that they own.