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Thread: Metering Technique...any problems here?

  1. #51

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    Re: Metering Technique...any problems here?

    Quote Originally Posted by Doremus Scudder View Post
    In other words, the "Normal" you are developing to is simply a different contrast index than that for traditional photo paper. In all other respects, the Zone System applies to scanning just as well as to "analog."

    Best,

    Doremus
    Exactly! And, personally I don't understand all this "develop one way for printing in the darkroom" and "develop a different way, if you're scanning." Not that anyone should do what I do, but I develop all my negatives such that a Zone VIII density is 1.25 - 1.35 over fb+f. I print these negatives in the darkroom as well as occasionally scan and I have some beautiful B&W desktop generated prints hanging on the walls of my living room. Several of these prints were produced from 8x10 negatives that I shot back in the 80's.

  2. #52

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    Re: Metering Technique...any problems here?

    I’m not an expert at the digital aspects yet, but my understanding is that generally speaking if negatives are destined for scanning/digital editing, you are best off with lower densities (ie lower gradient). As long as the negative contains the information you need, you can extract all of it and manipulate contrast at will. A higher gradient doesn’t really add any value, and can only degrade image structure.

  3. #53

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    Re: Metering Technique...any problems here?

    First you must know the true film speed for your film/developer combination. If you do careful tests, you may be quite surprised at the results, and at other factors like reciprocity failure, for which some users just apply the box suggestions. I tried many different film and developer combinations and paper and developer combinations too. Most of the differences are very subtle if noticeable at all, but if your negative is a good two stops underexposed, you are far out of the ball park when it comes to producing a quality image. Doesn't matter how may books the gurus and experts have written or how much their prints sell for, if you follow their recipes, which they all disclaim one way or another, you will get nothing worth printing. The old TriX and the old HC110 are gone. Who knows where the stuff comes from now? Not even worth discussing. Ilford came out with two virtual clones, HP5+ and Ilfotec HC, produced in a modern factory in the UK. I suggest rating HP5+ and developing for 5mins at 75* 1:31 or 7mins at 68* 1:31 for an exposure index of 400. If you rate at an exposure index of 100, and develop for 5mins at 68* 1:31 you will produce and other excellent "normal" negative with a bit more highlight and shadow detail. Adams would rate at 160 here, although sometimes he "feels the shadows need extra support" so kicks them up a Zone. This is like rating the film at 80! At least Phil Davis discloses the truth no matter how round about. You can easily pick off the film speed of TriX in 5 mins of HC110B 68* on his "Wonder Wheel" as 64.

    Do you need a guru to tell you your film speed after you send him a burnt offering negative and $5 (maybe it's ten or twenty now) when you can do it yourself for a little film and chemical testing. I have detailed my procedures on this forum for some time and no one has questioned them. so here they are again.


    Years ago I learned an excellent method to find the correct developing time and EI for any film. The source was an article by William Mortensen. Mortensen wrote some excellent books and articles about basic sensitometry. The last time I did this test was when I abandoned Tri-X and switched to HP5+ due to cost about five years ago. I proceed as follows.

    I set up my trays with my favorite developer HC110B (1:31), now Ilfotec HC (1:31). I pull out a sheet from the package in the dark. and then when the package is sealed again I turn on the room lights. This part of the test is done under the lights. I cut the sheet into five strips and mark them 1-5 by punching holes with a paper punch. Lets say the recommended time is 5:00. I want to see 3:00, 4:00, 5:00, 6:00 and 7:00, so I throw all the strips into the developer and agitate as usual until 3:00 when I move the No.1 strip over to the stop bath. Then I pull No.2 at 4:00, No.3 at 5:00, etc. I fix, wash and dry the strips as usual. What we are looking for is the best usable film DMax value. Obviously the film has been fully exposed! When strips dry lay down a page of news print on a table in good light. Find the strip through which the news print is barely visible. That's your developing time. Now to find the film speed.

    Go outside in unchanging light conditions and expose five sheets and expose one at the manufacturers rating and then the other four at one half a stop and one stop less and one half a stop and one stop more. In the dark, develop them all together for your newly derived time. Contact print them together exposing and developing the paper for maximum usable paper DMax value through the film base plus fog negative rebate area. Pick out the best-looking contact print and you have your film speed.

    Because my 7:00 negative looked the best on the first test, I did the test again with 7:00 as the central developing time and found that 8:00 was indeed too dense. This HP5+ time was the same as the as the developing time I had been using for Tri-X and film speed was also the same, EI400. I have also switched to Ilfotec HC developer due to cost and availability and find it to be a clone of the old HC110.

    Many of the last generation of B&W gurus favored a development time of 5:00 for Tri-X and suggested an EI of 64-100. You can do the above test backwards, developing for 5:00 minutes and finding the film speed. I like 100. The difference between negatives exposed at 100 and developed for 5:00 and those exposed at 400 and developed for 7:00 is quite subtle. Both could be considered "normal" or N negatives. The 100 negative has slightly greater shadow and highlight detail that only a careful, knowledgeable viewer could detect. This slight improvement might not be worthwhile trading for two stops in the field. I do routinely rate HP5+ at 100 under powerful strobe light in the studio and it produces beautiful skin tones.

    From here, if you are still with me, you can derive expansion and contraction schemes for both the 100 and 400 "normal negs". I do this by changing dilution rather than time. Make sure you have at least 1 oz. of the concentrated sauce for each 8X10 sheet or equivalent. For contractions I found that 3/4 oz. concentrate to 31 1/4 ozs. H20 yields an N-1 neg at a one stop loss in film speed and 1/2 oz. concentrate to 31 1/2 ozs. H20 yields an N-2 neg at a two stop loss in film speed. For expensions, 1 1/4 oz. of concentrate to 30 3/4 ozs. H20 yields an N+1 neg at a one stop gain in speed and 1 1/2 ozs. concentrate to 30 1/2 ozs. H20 produces an N+2 negative with a two stop gain in speed.

    If you look at the chart of Tri-X film speed in Phil Davis' BTZS book you can easily pick out the film speed in HC110B 5:00 as EI 64.

    Don't apply reciprosity exposure and development corrections for long exposures (1/2 sec. +) based on published data. Test for yourself and you may be surprised. I wasted a lot of time and effort producing long exposure negatives that were thick and flat. When I finally tested, I found no compensation was required for TXP or now HP5+ out to one minute.

  4. #54
    Vaughn's Avatar
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    Re: Metering Technique...any problems here?

    While exposure might be very close (with-in a stop), generally my negatives for platinum printing receive different (less) development than negatives destined to be used for carbon printing -- both are very different than my negatives I use to make for silver printing. Keep notes, make mistakes, and when you do something right, look at your notes and try to do it again.
    "Landscapes exist in the material world yet soar in the realms of the spirit..." Tsung Ping, 5th Century China

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