I've read a number of comments in this forum regarding calibration of film processing. Selection of a film/developer combination (and sticking with it) seems to be the first step. It sounds like development times and film speed need to be calibrated for my particular methods and tastes. I am not clear on how to go about this. It would be helpful to have an objective method to start with. Anyone have a favorite routine?

-- Marc McCloud (mccloud@uhavax.hartford.edu), January 04, 2000

Answers

Marc, This is too complicated to answer in a short post.Try reading Ansel Adams "The Negative" to get an overview. You can also go here: http://photography.cicada.com for a quick lesson or two. Most Zone System books recommend using a densitometer to establish film speed and Zone VIII density (or at least getting someone with a densitometer to read your negs for you). However, you can calibrate without one. See "The Zone System Manual" by Minor White, Richard Zakia et al. This is the way I've done my calibrations for years now. Good luck, ;^D)

-- Doremus Scudder (ScudderLandreth@compuserve.com), January 05, 2000.

Doremus is right, but I'll give you a quick idea.

Part 1: to calibrate your film processing =to calibrate your ISO=to calibrate for the low-Zone densities.

Part 2: to calibrate your film processing also= to calibrate for density/contrast=to calibrate development time/temp/dilution as per any given original luminence (sort of 'pulling' or 'pushing' or 'normal').

Part 2 is more obvious, but Part 1 is just as obvious if you read between the lines: perform (at least mentally for now) the following test:

take a number of exposures of a flat area on the same roll of film at a Zone 1 density (i.e., set your exposure to 4 stops under what the meter reads); if the recommended ISO of your film is, say, 400ISO, then I would suggest you expose the frames in the following order: 1) ISO 400, 2) ISO 320, 3) ISO 250, 4) ISO 200; 5) ISO 500, 6) ISO 640, 7) ISO 800 (I always screw the middle numbers up, but suffice is to say just keep exposing at 1/3 ISO increments plus-and-minus at least one full stop, i.e., with ISO 400 film, go plus-and-minus in 1/3 increments at least from ISO 200 to ISO 800...

...once you have exposed the whole series on one roll, then develop the film normally. The first frame with a density change (in general), will correspond to the proper ISO for that film, as used in conjunction with the same chemistry to develop it. I.e., if the first notable frame occurs at the ISO 320 setting, then with that developer and film combination you should always rate that film at ISO 320, EVEN IF the manufacturer states a different ISO. This can often lead to a big difference (many photographers rate TX at 200, not 400, for e.g.).

Hope this helps, but I still go with the following poster: get The Negative by A. Adams

shawn

-- shawn gibson (SeeInsideForever@yahoo.com), January 05, 2000.

Just to clarify, by "density change" I mean the first frame with an exposure of more than 'zero', technically noted as filmbase+fog level, i.e., the ISO rating = fb+f + "one Zone of exposure" (which is actually an increase of .3 if you're curious...).

-- shawn gibson (SeeInsideForever@yahoo.com), January 05, 2000.

Get a copy of the Zone VI Workshop by Fred Picker. This a simple way of doing tests. You don't need a densitometer as he suggests. You can use a hand held light meter on a light table to see which negative is .3 ND + fog. Harvey

-- Harvey Augenbraun (mrsciecne9@aol.com), January 05, 2000.

In addition to the above you should take a look at the book "Basic Techniques of Photography, Book 2" by John P. Schaefer. This contains a really easy way to do densitometry without a densitometer. It is the clearest and most reproducible of all the systems I've tried.

Book 1, incidentally, is the best single volume about photography that I've seen.

Both books have the sub-title "The Ansel Adams Guide" and are available as large format paperbacks. Amazon.com has them and so does my local mega-bookstore.

-- Don Karon (karon@ibm.net), January 07, 2000.

From the book by Roger Hicks and Frances Schultz: The authors state that a friend of theirs, who is renowned for the quality of his prints, just develops films in the developer recommended by the manufacturer and using the method and time recommended by the manufacturer, and starts testing by rating the film at the recommended speed. If the first roll comes out under-exposed, he just rates the film at 2/3 of the speed used previously, leaving the development time unchanged. It sounds nice.

If you have the impression that your negatives are too hard or too soft, but the speed is fine (i.e. the shadows still show some detail), change the development time. If the contrast is too low, try 5% more development, if it seems too high, try 5% less. Repeat as necessary.

There are plenty of other methods, some relying on extensive test-target shooting and printing, others on the use of a densitometer (the latter being the fastest methods, but also the most expensive). Yet: If your speed settings for a film works for you, and the negatives print well on a medium grade, you are already in the ball park. Never touch a running system unless you expect considerable improvement!

All the fuss about the "correct" speed and gradient is only justified if you can measure the exposure and contrast to sufficient accuracy. If you only use an averaging wide-angle meter, there is, in my opinion, not much to be gained by sophisitcated calibrating.

The most important thing about calibrating is that you get familiar with the material and methods you use, and that you keep them constant.

-- Thomas Wollstein (thomas_wollstein@web.de), January 10, 2000.

If you use mostly the same enlarger, it is best to calibrate your negatives with that enlarger. Expose two frames (single tone target) one with the metered exposure, the other 3 steps more. After developing, put these in the negative carrier half and half. Give a test strip of your usual printing paper an exposure, which gives medium gray of the normally exposed half - use a gray card to compare. That exposure should give a just visible shade of gray of the +3 exposed frame. (When the strip is dry, of course). If the half is white, gray is not visible, develop the next roll shorter time. If the half is clearly gray, develop more next time. Development is just suitable for your use if the +3 shade is visible, but barely visible.

Once done, the procedure is easy to repeat with new film or developer. At least with 35 mm you can sacrifice two frames every now and then.

Sakari

-- Sakari Makela (sakari.makela@koulut.vantaa.fi), January 10, 2000.

Many thanks to all for the responses. I followed the references cited as much as possible and was able to glean a great deal. The source for the zone system, "The Negative", Ansel Adams is excellent and wonderfully amplified by "Basic Techniques of Photography", John Schaefer. I was not able to find the book 2 however. The zone system discussion and calibration methods outlined on photography.cicada.com is magnificent. The main problem from my point of view is the lack of a densitometer. Someday...

For now other less objective techniques will have to suffice. An e-mail inquiry to Kodak pointed out a method that at least involves a "standard" reference. I plan to use the "Kodak projection print scale" and test methods outlined in Kodak Workshop Series Book, "Advanced Black and White Photography" p 54-55. There are two procedures outlined: film speed determination and development time determination. In each, comparison of negative densities with the print scale is required. An interesting wrinkle I'll have to work out is that the print scale density is compared to the negative 'added to that of a blank frame'. This is clearly the fb-f of the blank frame. I assume that the print scale is net density and that I could place the blank frame behind the print scale (illumination from behind) to make the comparison.

frame density - (fb-f) = standard frame density = standard + (fb-f)

I am hoping that my spot meter will be helpful. (Ansel Adams does remark in "The Negative" about .1 ND equating to 1/3 EI. I'll be intersted to see.) While it would be better to use a correctly calibrated densitometer, this method does at least involve a "standard" for comparison.

-- Marc McCloud (mccloud@uhavax.hartford.edu), January 16, 2000.

That little piece of algebra needs to look more like this:

frame density - (fb-f) = standard

frame density = standard + (fb-f)

-- Marc McCloud (mccloud@uhvax.hartford.edu), January 16, 2000.

Update. I tried the above and was not able to adequately discern the variations in negative densities. In my further readings I came across The New Zone System by White. Well, written in the 1970's its not new but I did find this reference quite useful. I don't think it is in print anymore but was able to get a copy from the library. Without getting into too much detail, the method involves making test negatives followed by printing of the negatives. The results are compared to standard gray cards. I have been able to identify my corrected EI and normal development for TMY in xtol. This book also discusses some interesting zone system manipulations that I had not read about before. The most interesting is a method for expansion and compaction (as White calls it) that pivots around zone V rather than simply expanding or contracting from zone 0. At any rate, for those of us who want to use the zone system and a densitometer is not available I recommend this book.

-- Marc McCloud (mccloud@uhavax.hartford.edu), February 28, 2000.

The book title should be The New Zone System Manual by White, Zakia, Lorenz

-- Marc McCloud (mccloud@uhavax.hartford.edu), February 29, 2000.