Testing film? Using a densitometer?

[Doremus Scudder]

@ OP,

Michael is the guy to follow here. Forget the film testing, just rate your film a bit slower than box speed for more of a safety factor. (FWIW, my ZS E.I. tests usually come out 1/3 stop slower than box speed.)

The important thing is to nail down development times. But you don't really need a densitometer for this either.

If you're printing traditionally, then find a scene with a wide range of tones in well-separated areas that fulfills the criteria of "Normal." Make several shots, keeping careful notes about your metering; where you place the shadow value and where all the other values fall. Then develop a negative at your starting development time and print it on the paper you intend to use most at an intermediate contrast grade (2-3). When printing, match the shadow value to where you placed it when shooting (yes, this is subjective, but how we meter and place is an important factor here). Make a straight print at this exposure, dry it down and sit down with your print and the metering notes. If things match up well, then you've come very close to an ideal "N" developing time. If the high values are too hot, reduce the development time by 20% and try again; the reverse if the highlights are too dark, reduce the time by 20%.

Make a print from the second negative in exactly the same way and evaluate it. At this point, you should have a handle on on or two development schemes (N, N+1 or N-1). Interpolate an intermediate time if needed and go out and shoot. Keep good metering notes and you'll be able to tweak your development times as needed when things go a little one way or the other.

That's really all you need. Keep in mind that you just have to get the neg somewhere in the middle of the available contrasts of paper you have available. Then you use paper grade changes, etc. to refine when printing.

Best,

Doremus

[Drew Wiley]

You pay a bit more for a CALIBRATED step wedge (with a an attached ledger showing the factory-measured densities of each step), but they can be typically had for around $30 new from graphics suppliers or some darkroom suppliers. And I would personally recommend a calibrated one if you are going to attempt visual densitometry, or even later on double-check the accuracy of an electronic densitometer. Don't buy old used wedges. They could be stained from handling, and have often yellowed, making evaluation of fbf density a headache. And no sense making your own. Special films were used for this in the past: either Eastman Color Separation Film or Super-XX due to their extremely long straight characteristic curves. I don't know what they substitute nowadays; but it's probably TMX100, which would certainly be the most logical candidate. Tech Pan would be worthless for this kind of application.

[Neal Chaves]

I started years ago with Tri-X and HC110B (1:31 at 68*), then switched to HP5+ in HC110B. Now changing over to HP5+ in Ilfotech HC (1:31 at 68*) because no suppliers will ship HC110.
Try this. It should put you in the "normal" ballpark at full emulsion speed with the first sheet. I develop HP5+ 8X10 rated at 400 EI one sheet at a time in an 8X10 tray in Ilfotech HC 1:31 at 68* for 7:30. I immerse the sheet directly into the developer and agitate for the first thirty seconds, then five seconds each following thirty seconds.

Ilford's data suggests 6:30. If you do that and rate at 200EI you will also produce a nice "normal" negative with slightly increased highlight and shadow detail and slightly reduced grain size. If you rate at 100EI and develop for 5:00 and you can tolerate the loss in film speed, you will be quite pleased.

[AndyL]

WOW, Thanks to all of you for commenting. I think I learned more in a day reading these posts. I will follow your combined advice and report back when my testing is done. Thanks

[Luis-F-S]

If you have access to a densitometer, then it's really not that hard to simple exposure/development tests. Fred Picker's Zone VI Workshop, probably available at your local library, lays out a good method, although he works in 1/2 stops, while I prefer 1/3 stops, as that mirrors available film speeds.

You're looking for the negative that gives a Zone I density of at least .1 above film base plus fog. (That's traditional zone system practice. I prefer 0.15.)

Now you know your normal film speed. The next step is to fine tune your development time.

You now have your Normal (N) film speed and development time.

Peter speaks the TRUTH! Using a light meter as a densitometer or a "visual densitometer" is a bunch of baloney. Fred Picker tried to come up with an intuitive method for most photographers (who are to lazy to do it right) and he offered to read negatives with a densitometer and return them with values. You can buy the Zone VI workshop used for $3.99 shipped. That's less than the cost of a single sheet of 8x10 film. But you do have to get off your computer and read it!

With 8x10 cost north of $5/sheet, you can waste all the film you can afford with your light meter or visual densitometer, but all you'll have is a bunch of wasted film or bad information which is worse than no information.

I follow Oliver Gagliani's methodology that he taught in his workshops in which he shot a "daylight" bulb behind a sheet of plexiglass. The front was masked with black paper, so you only had a bright circle in the center of even ilumination. You took a light reading of that area, set your shutter speed and aperture and then used ND filters to decrease the light instead of stopping the lens down as that is much more accurate. Then choose the ASA and developing time for a Zone I expose which was 0.15 density units over film base plus fog. That nailed your film speed and developing time.

Oliver was a pupil of Minor White and Ansel Adams and he attended the California School of fine Arts in the 1940's. He took up photography after loosing some of his hearing in the "big war" so he could no longer play the violin. After seeing a Paul Strand show, he was so impressed that he decided to become a photographer. I am fortunate to have several of Oliver's prints which I can always use as a frame of reference.

It's photographic sensitometry (aka science). Any other "easier systems" or short cuts are going to be flawed. It's just a matter of how good a negative you want to make, and how easily it will print. If you don't care, or you want to guess at it, go ahead. I'm sure the same "experts" who can't produce a printable negative will have all sorts of convoluted "techniques" to print them.

The last two X-Rite 301 densitometers sold on the 'bay for well under $200.00. That's two boxes of 8x10 Tri-X. You can run your tests using 4x5 film as long as the unexposed film base has the same density and fog, or you can cut down 8x10 sheets to make it last longer.

If someone wants to send me up to 5 LF negatives with a self addressed stamped envelope, I'll read them on an X-Rite 301 and return them. You can PM me for the address. I'll do this as long as it doesn't get out of hand.........

L

[Tin Can]

Olives's plan is pretty much what I will try to do today.

Test with DSLR for up to 10 stops in 1/2 steps with a known quantity studio strobe and diffusion.

I can then check density results in PS.

The strobe steps down very precisely, I check it all the time.

I made Pictorico step wedges with PS until I threw out the damned printer.

[Luis-F-S]

I rather doubt that Oliver used PS.

[Tin Can]

I rather doubt that Oliver used PS.

!

I am simply checking my light at the moment, then back to film.

[Jerry Bodine]

...You can run your tests using 4x5 film as long as the unexposed film base has the same density and fog, or you can cut down 8x10 sheets to make it last longer....

Luis, here's an fyi that I think is appropriate here. Years ago I queried Ilford about whether it's technically sensible to do film tests using 4x5 sheets and apply the results to larger sizes; here's an edited version of their response:

… all sizes of sheet film are cut out of the same master rolls, so the different formats you mention will have identical characteristics. … There can be small differences between 35mm, 120 and sheet film as these do use different bases and slightly different emulsions. …We endeavor to manufacture all three types to be as close as possible in order for development times to be consistent across the range for any one film type (and they are for most practical purposes).

Bottom line you will not need to duplicate your tests for 5x7 and 8x10.

[Luis-F-S]

As long as the film age and storage conditions are similar, otherwise the fb+f will be different. My 20 YO Tri-X which has been frozen, has a fb+f 3 x that of new film.