Learner's calibtration woes.

[Richard Sanders]

Hello. I feel rather foolish but in my attempt to become (slightly) more proficiant I have decided to learn the Zone system (apologies if I should have placed this post in that category).
My troubles started after processing my negatives to determine film speed. I had followed the instructions laid out by Fred Picker in his book. I used Vuescan to read the density of the negatives as I do not have access to a freestanding densitometer and found film base plus fog to be 0.16. However my Zone 1 density (at it's minimum) was 0.38 and even ranged upto 0.98! I had tested the film (Ilford HP5) at 800, 400, 300, 200 and 100.

My developemt procedure was a 2 minute presoak, follow by 22minutes in D76 (1+3) with agitation every minute (lift film rack from tank and reimmerse, four times) followed by the usual stop bath and fixing times. All water came through a Pro-Co filter and chemicals were at 20C.

How reliable is the densitomer function within Vuescan?
I know a presoak means that development times should be adjusted, but I thought that this was to prevent highlights 'blowing out'? Have I just plainly biten off more than I can chew?
My plan is to take the original negatives to a densitometer and also test again.
Should my density reading turn out to be accurate it would mean that all of those negatives were over exposed and that I would need to rate the film even higher than 800??!
Apologies for the poor and over dramatic use of grammer and spelling but I am rather confused and determined to get it right so if you could let me know what glaring mistake I have made I would be very appreciative.
Many thanks in advance
Richard

[Brian Ellis]

My guess is that there's something wrong with your "densitometer" readings. However, I do have a couple other thoughts.

First, Ilford recommends against a presoak of its films so I'd leave that step out . A presoak doesn't accomplish anything with modern films though for most films it probably doesn't hurt anything either. But since Ilford specifically recommends against a presoak I'd leave that step out.

Second, why the highly diluted D76? The "normal" use of D76 is either straight or 1-1. When doing film speed tests you're supposed to use the manufacturer's recommended development times (since at that point you haven't yet done your own development time tests). Maybe Ilford or Kodak give times for 1-3 but that kind of dilution, if used at all with D76, would be used to control blown out highlights. Hopefully you have no highlights at all in your film speed tests since you're exposing and developing for a Zone I density.

Third, while I've never used D76 at 1-3 and so don't have a real good feel for a normal time, I've used it at 1-1 for many years, it's my standard developer with HP5+, and my normal time is only 6 minutes when diluted 1-1 (at 75 degrees) so your 22 minute time strikes me as high even at a 1-3 dilution.

So I'd suggest that rather than trying to find a densitometer to read you present film, you first redo your tests leaving out the presoak, using D76 straight or at 1-1, and using the time, termperature, and agitation method given by Ilford. or Kodak for HP5+ for whichever way you choose.

[Jim Rhoades]

I'm not a Ilford HP5 user, so someone else will have better info. But from a Tri-X guy I have to ask why 1+3? I have long used D76 1+1. 12 min. for a large dip & dunk tank. 9min for a small rollfilm tank and 61/2 min. for BTZS tubes. (New TRI-X) I think you should back off the agitation to two tilts. Old Tri-X was two min. shorter in the tanks and half a min. in the tube. This is what works for me YMMV.

[Jim Rhoades]

Oh, a add on. My temps are 68 for the tanks and 70 for the tubes. Brian cooks his film because he lives in Florida :-) Location has a lot to do with how you process your film. He also makes very nice prints. Try his time and temps for HP5, you can't go wrong.

[Richard Sanders]

Thank you for the responses. The 1+3 and presoak were on the advice of a tutor at my college. The 22 minute developemnt time for this dilution came straight from Ilfords data sheet. I shall retest, leave out the presoak, use the D76 at 1+1 and reduce the agitation to two tilts per minute. Oh and go find a proper densitometer. Again many thanks for your help. Wish me luck.

[Henry Ambrose]

Hi Richard,

About the only way to use a scanner as a densitometer is in a relative fashion - scan all the sheets together in one pass and compare them to each other. There is no way to determine what your scanner is REALLY doing when you make consecutive scans. Even when you do a single scan the numbers you get will not be comparable to other scans or the readings from a real densitometer.

I'd also suggests that you use a more standard dilution, not only because I don't have any recent experience with D76, but what Brian and Jim wrote makes sense. Drop the pre-soak. I do like longish development times but 22 minutes of lifting and dropping hangers might get old and who knows how D76 acts when more diluted? And as they pointed out using standard times gives you a reliable starting point. After all, you are not reinventing the wheel, rather setting your personal slant on pretty well documented technique.

And you didn't ask this - but I'd set up (or find) a "typical scene" with shadows and highlights something like you are used to photographing and shoot sheets at 160, 200, 250, 320 and 400 and print the negatives. The best print indicates the speed to use for your normal exposure and development. First trial use the dilution and times suggested by a reliable source. Adjust times from there as needed for subsequent trials. Two or maybe three iterations and you should be finished. Or shoot three sets of film at once and then develop each set at different times, again guided by published data.

[John Cook]

I agree with all the above. No presoak, better densitometer, etc.

However, I have used D76 at 1+3 for several years with great success. This dilution provides slightly more apparent sharpness (more like Rodinal) with slightly more apparent grain. But with large format, who cares about grain?

The development time for 1+3 dilution will be longer and will of course vary with equipment, etc. While I usually follow Ilford's advice to the letter, 22 minutes seems a bit long to me as well.

There is some kind of a government standard hanger tilt procedure which has been used for decades and gives foolproof results. Several books have excellent pictures and diagrams. It is lift and tilt 45* to the right. Submerge. Lift and tilt 45* to the left. Submerge. Then repeat the two tilts. All should be done as quickly as possible (within 5 seconds) once per minute.

[Joe Smigiel]

You might try taking a 35mm roll and expose it to a very evenly-toned wall with the camera at infinity focus and expose a series of frames from about -6 stops from what your meter indicates to however far you can go using 1/2-stop increases in exposure for each adjacent frame. Develop the film and then take it to a custom lab and ask them to read and record the densities of each frame for you. You'd then have a filmstrip with known densities you could visually compare on a lightbox to your calibration runs and use for any future testing. You might be surprised at how accurate this is and it costs a whole bunch less than purchasing a transmission densitometer.

Buying a stepwedge from a graphic arts dealer would do the same thing, but the larger size of the 35mm frames makes the comparison easier.

[phil sweeney]

Hi Richard,

Until you get a chance to use a good densitometer, look at your test results by eye and you should find that 0.1 over fb+f should exhibit a slight density over an unexposed portion of film. Try to view all your results together at once on a light table. I'll bet you can figure the speed by eye and then verify with a densitometer. 0.2 or greater should be a significant (not slight) increase in density.

[Louie Powell]

Richard -

Don't give up - film testing is important but it's not totally inuitive. It took me severay tries to get my brain calibrated to what is required.

One thing to be concerned about - it's entirely too easy to get trapped into a perpetual test mode. You should do the tests until you feel you have iterated to a repeatable process with defined parameters, and then you should go out and make pictures with the confidence that you have control over the fundamentals..

Brian's suggestions are excellent. I agree with everything he says except for the point about presoaking - yes, Ilford does not recommend a presoak, but I feel it's a good discipline, and if you include a presoak in the routine that you develop in your test series, then your process will be calibrated for whatever effect it might have on development.

You don't absolutely have to have a densitometer. You want a Zone I negative to be distinguishably denser than a Zone 0 negative (Fb + F). With roll film, the distinguishable difference is traditionally 0.1 (about 1/3 stop); its traditional that large format film is exposed for slightly more density in the Zone I shadows. Richard Kagan, an art photographer who taught me the Zone System, is famous for rigor in processing (one of his famous quotations is "close enough is NOT good enough"). He suggested two ways of measuring shadow density that don't require a densitometer.

The first is to use a 1 deg spot meter. Put the negatives on a light box, and use an ordinary spot meter to measure the light transmitted through them. If the light through the Zone I negative is 1/3 stop brighter than the light through the Zone 0 negative, then the Zone I negative density is Fb+F+0.1. Likewise, 2/3 stop is Fb+F+0.2. So if you are aiming for something between 0.1 and 0.2, then you want something between 1/3 and 2/3 stop of addition light as measured by the spot meter.

The second trick is to purchase a 0.1 density neutral density filter (available from Kodak in the gelatin form). Put the test negative and the Fb+F reference negative on the light box, and then lay the filter chip over the reference negative. If, to the naked eye, they appear to have the same density, then the test negative is approximately Fb+F+0.1. Repeat the test with two filter chips over the reference negative to look for Fb+F+0.2.

[Bruce Watson]

I think you are probably overdeveloping your film - by a lot, apparently.

While shadow detail on film doesn't vary much with development time, it does vary some. If you really over develop your film, you will also develop more shadow detail. This would account for your EI showing up as 800.

If it makes you feel any better, I did something similar with HC-110 and Tri-X when I was starting LF film development. I misread the Kodak data sheet, and was over developing my film by about 40%. This gave me an EI of 1000. I knew something was wrong, but couldn't figure out what. The fact that my negatives were really dense didn't register in my mind - I was scanning, and the scanner didn't care how dense my negs were.

I finally got the development time down and the dilution up to the point were my negative density wasn't overwhelming. A film speed test at this new development time gave me an EI of 250, which is where everyone said it should be in the first place.

That said, the massive development chart (http://www.digitaltruth.com/devchart.html) does list your combination at 20 minutes. Perhaps you mixed your developer 1+2 instead of 1+3?

[Gene Crumpler]

Why don't you use the standard times for development and make some prints. The rule of thumb is to cut the manufacture's ISO by half as a starting point. This should put your shadows at Zone IV. After you try this, you should be able to make adjustments to suit your light source. The print is what counts! KISS

[John Berry ( Roadkill )]

You hve to marry the neg to the paper you are using. I put a test strip at the egge so that part of the paper is out from under the neg and make a test strip to find max black where edge and uncoverd match. I find they will match but needs just a little more to get max black This will be the base exposure for that paper. Contact the neg and see where it falls. If it's dark your under exposed.Too light over exposed. See where the shadows fall to determine shooting speed. Check to see where highlights fall to determine developing time. Too contrasty reduce time. Flat increase. I haven't used HP-5 in a long time. Reading the post here gave me information that FP-4 would let me do more with the neg than I could do with HP-5.
I agree with others, no presoak, 2 tilts every30 seconds. If test print is close but just a little contrasty try agitation only on the minute. To a certain extent you can use time for density and agitation for contrast. I've been at this for 35 years, and other will tell you also that the print will tell you a lot more than a densitometer. I just "won" an X-rite 310 of the bay a couple of months ago. The kids just moved out a couple of months ago and now I can afford a toy. Them two guys only ate one meal a day. It started when they woke up. Tax deduction only covered ketsup.

[Jim Rhoades]

Louie Powell's post reminded me that we were in the same class with Richard Kagan, about 4 years ago, I think. He gave out little chips of the O.1 filter taped to a cutout on black paper. I still have mine on my darkroom wall and use it for any testing that I still do. This overlaying of the filter and the Fb+F standard negative and matching it to test negatives has saved me $1,000. for a densitometer. Your eye can see the difference as well as a desitometer. At least enough to make a fine negative and print.

The other part of keeping it simple is to stick with one film and developer until you really know it.