Testing film? Using a densitometer?

[Bill Burk]

Keep in mind that a densitometer, used with a sensitometer and a few development time tests can provide you with a family of characteristic curves for the film.

The characteristic curves tell you how film responds to light and development in terms of density... so this is just stating the obvious (that those tools and tests can get you this).

I like to think of exposure index as an "overlay" to the family of characteristic curves, drawn in pencil and erased and drawn again if you change your mind... You can move exposure index around. Even the speed points and Delta-X are discussions about the curves and how they are interpreted.

But the curves are just there, they are what they are and can be drawn in ink.

[Drew Wiley]

Plotting families of curves for various developers, developing times, etc, is quite a bit of work. I don't personally do that except for truly fussy applications like
matched color separation negatives, associated control masks, and so forth. But going through this kind of exercise at least once in depth does have one significant advantage: it teaches you how to read published film curves. One you realize how minor differences in curve shape are actually logarithmic and can often translate into truly different looking images, you can select your appropriate films with a lot less intervening headaches. Some people stick with a single film and developer for as long as its own the market. Others of us tailor any number of films and developers to different specific situations. In either event, the data only takes youso far. You gotta shoot/print, shoot/print, shoot/print until it becomes second-nature, spontaneous, just like a well-broken-in pair of gloves.

[macandal]

Suffice it to say if you plan on finding an EI using a Zone System-type test, you can skip that part and simply reduce film speed by 2/3 stop (or round it to either 1/2 stop of 1 stop).

So, ASA 100 = EI 64 (as would be in my case since I'm shooting Delta 100)?

[macandal]

Here are the results in my system for other films: Acros (80), Delta 100 (64), HP5+ (200), Tri-x (250).

Nice photograph, nice contrast, Peter. What developers use for the films you mention? Especially for Delta 100 (64) [that's what I use]?

[Peter De Smidt]

For the Rialto Beach picture, I used Xtol. For Delta 100, I've used DS-10. I've moved away from Xtol mainly because I don't like to store it for a long time. There are so many terrific developers, such as the Pyrocat formulas, Ryuji Suzuki's developers, Crawley's recipes.... Since I develop film sporadically, I've switched to easy to make developer that I mix up shortly before use. Currently, I'm using DS-2. I recently purchased a flash spot meter and ran a few tests in the studio. If I would've taken the advice of many, I'd have shot Acros at EI 50. In my case that would've underexposed the film by 2/3 of a stop. A few quick tests are all that's needed to hone in on a good exposure and development system for your particular use and requirements.

[macandal]

For Delta 100, I've used DS-10.

For Delta 100, I've used DS-10.[/QUOTE]Who makes that or is that one of those home brews?

Thanks.

[Peter De Smidt]

It's a homebrew, but there are a lot of good choices.

[macandal]

So I have another question. Could this method be applied to color films? That is, if I'm shooting Ektar 100, for example, I would shoot it at EI 64 and process according to the developer you're using? What about slide film? Would I do the same?

Thanks.

[MultiFormat Shooter]

So I have another question. Could this method be applied to color films? That is...process according to the developer you're using? What about slide film?

No, color film (both E-6 and C-41) only has one set of developing chemicals, so you cannot pick from several different developers and adjust. In the case of C-41, you can shoot an 18% gray card at several different EIs (with the standardized development time and temperature) and evaluate the negatives on a densitometer. The manufacturer's technical information should give the proper density for a correctly exposed negative shot on a gray card. Then, find the negative that matches this density and set your meter the corresponding EI.

[Pere Casals]

So I have another question. Could this method be applied to color films? That is, if I'm shooting Ektar 100, for example, I would shoot it at EI 64 and process according to the developer you're using? What about slide film? Would I do the same?

Thanks.

Here

http://www.freestylephoto.biz/pdf/pr...structions.pdf

You have instructions for Tetenal E-6.

There are clear instructions for push pull. I see it useful for the case I made a known mistake in the exposure and I want to correct it in the development.

One advice, datasheets should be read with a loupe. Don't miss a single word.

Datasheets are made by skilled technicians and contain very important knowledge. Later you can do it in a different way or even detect mistakes in a datasheet (not common). But always use the loupe.