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  1. #11

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    I sacrificed the dark slides from a couple of really ratty film holders I had to make a set of masks, allowing me to make eight separate exposures on one sheet of film. Each has a ¾" hole drilled in it, offset to one side of the holder. Using each in turn, and swapping them around in the holder allows the eight individual exposures.

    I use one sheet for determining EI, including a zone VIII exposure, to see how close my standard development time using the selected developer is to the required time (if it is way out I will use another sheet for EI/zone VIII). Then a couple of sheets for -2/+2 development times, and interpolate for my -1/+1 times.

    If I am evaluating the negs by eye, I shoot a textured surface, if I am using a densitometer, I shoot a plain surface.
    Attached Thumbnails Attached Thumbnails the_four_darkslides.jpg  
    Last edited by snallan; 02-22-2008 at 04:31 AM. Click to view previous post history. Reason: Additional info
    Steve

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  2. #12
    David A. Goldfarb's Avatar
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    If you want to determine the full range from -2 to +2 (presuming the film you are testing is capable of that much expansion, and you may discover that it isn't, which is useful to know), I could see using around 25 sheets. That's one speed test and five development tests, and maybe more if you decide to try a different developer for -2 or -3 or maybe run another speed test for +2 or if you can't get +2 run a test for selenium intensification, etc. That said, I don't test every film under all conditions.

    snallan's method with the darkslide masks is a good one for saving some film. I've also seen a single darkslide mask with 8 holes covered with tape, which is another approach, if you don't have so many spare darkslides.

    Another method is to cut up a sheet of film for development tests. Just make sure you've got relevant detail or a Zone VIII patch to read on a densitometer in all the strips.
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  3. #13
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    There is an alternative - and I know some people are going to start twitching their nostrils but how about developing by inspection?
    It basically takes two sheets to calibrate. Shoot a negative with a normal range of tones and use the manufacturer's recommendation of development time. At about 75% of that development time you turn on your (magically appearing) dark green safelight. You look on the film base side (Tmax 100 & 400 won't work by the way) and you take a look at the highlights. When they start really coming through, starting to look dense it's time to pull the neg. If they seem to need more, give it another minute and inspect for a few seconds again. It's time consuming, and a bit laborious, but it has that element of control that is wonderful to have. There is a wonderful piece of reading on it on Michael Smith's and Paula Chamlee's web site.
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  4. #14

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    what the!

    just expose and develop one sheet as per the manufacturer recommends after taking a reading from a mid tone, LOOK at the result, if a little thin decrease ISO or vice versa

    it don't got to be overly technical, you is all kidding yourselves with this constant need to test

  5. #15
    Thomas Bertilsson's Avatar
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    Yeah, I am forced to agree with that one. I got a bit sick of it too and bought a tank and don't worry about it anymore. Negs come out fine anyway.

    Quote Originally Posted by Ray Heath View Post
    what the!

    just expose and develop one sheet as per the manufacturer recommends after taking a reading from a mid tone, LOOK at the result, if a little thin decrease ISO or vice versa

    it don't got to be overly technical, you is all kidding yourselves with this constant need to test
    "Often moments come looking for us". - Robert Frank

    "Make good art!" - Neil Gaiman

    "...the heart and mind are the true lens of the camera". - Yousuf Karsh

  6. #16

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    Quote Originally Posted by Ray Heath View Post
    it don't got to be overly technical, you is all kidding yourselves with this constant need to test
    No constant testing at all. I test any new film/developer combo once, and would only retest if I got markedly different results to those I would expect from it. I performed three tests last year, because I started using Pyrocat-HD, but they were the first in about four years.
    Steve

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  7. #17
    David A. Goldfarb's Avatar
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    I don't test that often either, but if someone is learning about it for the first time, one can learn a lot from a full range of tests. After that, you have a much better idea about what to expect and how to control contrast for uncontrollable lighting conditions.
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  8. #18

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    There are many ways to test for film speed. I recommend two methods.

    1. The old Fred Picker method, as outlined in his book The Fine Print in Black & White Photography, is a simple test that works well, but that involves exposing a fair amount of film. You can get a modern version of this testing method from Richard Ritter at www.lg4mat.net. Go to his page and click on Film Speed Test.
    2. The method that I use is BTZS methodology, developed and promoted by the late Phil Davis. You can read about this method at http://www.btzs.org/, or buy Beyond the Zone System by Davis. This method requires use of a densitometer (but stop meters can be calibrated to be used as densitometer) and, for most efficient results, a curve plotting program called WinPlotter. BTZS is by far the most efficient method of film testing there is. It takes me about two hours to run a full BTZS test of a new film and developer combination, including exposure, development, reading of the densities with a densitometer, and plotting.

    Both methods are fairly mainstream and there are quite a number of folks on APUG who can help you with methodology and terminology if you have problems.


    Sandy King

  9. #19
    JBrunner's Avatar
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    You can make incremental exposures on one sheet of film by pulling the dark slide out in increments.

  10. #20

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    I would add this to Sandy's comments on the BTZS testing: once you undertand the basic principles of BTZS and how to meter, you can "borrow" someone else's data (exposure and development times) and use it very effectively without ever doing your own testing. I did this because I do not have a densitometer, a means of accurately exposing the film for the test, or the plotting software. Sandy King and others on this site are very generous with their BTZS testing data. Since I started using this system I have made a huge improvement in the quality of my negatives. If you keep careful notes you can tweak the details as you go along.

    The other approach I have taken with roll film is to expose at the manufacturer's rating (more or less) and develop for the recommended time. This works too!

    -Paul

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