Follow-up to "Zone System... relevance when scanning..."

[Capocheny]

Quick question as a follow up to Jimbobuck's thread, "Zone System... relevance when scanning negs digitally."

How many of you Zone System/BTZS users here test and determine the true ISO for each of your films?

For example, if you buy 2 boxes of FP4+ and they each come from a different batch, do you do individual tests on each box? Or, do you assume that the true ISO will be minimally different and, therefore, you use the same film speed for both boxes?

Now, let's assume that your gear (i.e., shutter speeds) is consistent and you don't process your own film (but, you take it to a Pro Lab for processing)... you've done your true speed tests on one box of FP4+, will you do it for the next box of film you purchase? Or, is it okay to use the film speed you've determined to be true from the last set of tests?

Now, I DO understand that one does these tests to "calibrate" your shutter speed, aperture opening, meter, and processing technique. What do you do if you decide to use a different meter? Or, a different lens? Again, let's assume that your film goes to a Pro Lab for processing. Do you still use the same results from one set of tests?

I studied the Zone System back about 25 - 30 years ago and am now looking to get back into doing more of it. I'm just now in the process of reading The Negative again...

My purpose in posting this thread is to see what all of you folks do...

So, thank you for all of your comments in advance.

Cheers

[Andrew O'Neill]

I've never bothered testing boxes from different batches but I do make one exposure of the back yard just to on the safe side. I make sure my solutions are fresh. If the film looks "off", I'll then take a shot of my "zone wall" (idea stolen from Gorden Hutchings zone board), process and read densities with my densitometre. I've never had a shot of the backyard be off.
It's probably worth it to buy a whole wack of boxes from the same batch and keep in the freezer. Then you don't have to really think about any variations of film speed.

[Andrew O'Neill]

I forgot to comment on metres...I've always had the same metre. If I got a new one, I would run a thorough test. If I aquired a lens, I would do my bark yard test first. All my lenses are pretty consistent in that I don't fuss about IE...except for my 120 lens which I always give a stop more than what my metres indicates.

[Brian Ellis]

I assume you're talking about b&w film. B&w film from major suppliers such as Kodak, Agfa, Fuji, and Ilford has historically been extremely consistent from batch to batch, week to week, month to month, year to year. These companies had/have outstanding quality control for b&w film. I've never heard of people making it a practice to routinely re-test just because of possible changes in the emulsions over time without some indication that a change has in fact been made but maybe people do and I just haven't heard about it. FWIW I've never done it myself.

Of course if the film itself changes, as TMax did a few years ago, or if development conditions change (e.g. you move to a new area with a different water supply) then most people would re-test (at least I think they should). As major companies drop out of the film market and smaller companies play a more dominant role it will be interesting to see if the same quality control we've been taking for granted continues.

BTW, some form of film testing to determine at least your own EI for a given film is a good idea whether you use the zone system/BTZS or not.

[Capocheny]

Hi Andrew, Brian,

Thanks very much for your comments on the question posed... very much appreciate it.

Brian,

Yes, I'm speaking predominantly about B&W films here. So, given that there is historically a very consistent production and quality control with regards to batches of film over time... is it fair to say, then, that we're performing the EI test in order to calibrate for our shutters, meter, and processing techniques?

In my personal situation, I have my films processed by a Pro Lab; my shutters are adjusted once a year, and my meters are calibrated once every couple of years by the manufacturers. The meters, fortunately, are pretty much a good match between each other.

Before I get out and perform my own set of tests... I'm curious as to what shooters here use as their true EI for films such as:

1. FP4+

2. HP5

3. T- Max 400


TIA.

Cheers