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  1. #1

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    Testing B&W Film Developers.

    Although I no longer have my old copies of Practical Photography magazines, I can recall when they reviewed several different B&W film developers by shooting several rolls of Ilford FP4 35mm film and then developing each roll in the various processing solutions. My memory is a little sketchy here and some of you might have read the particular magazine (publishing date/year long forgotten). I seem to remember that the films were then sent to a laboratory so that each negative to developer combination was photographed using a 35mm Camera loaded with a slow Tungsten balanced colour reversal film which was attached to a microscope. Each image represented an enlargement of around 36-40X magnification or there abouts. A guy by the name of Mike Buxton did this stage of the work. I remember that Agfa Rodinal yielded the grainiest of the negatives while the finest grain was with Ilford Perceptol.
    Does anyone know which issue and year that this magazine issue was?
    Cheers,
    Keith.

  2. #2
    Kevin Caulfield's Avatar
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    I recall a test they did, probably more recently than the one you remember. If I remember correctly they used Delta 100 in the various developers. Paterson FX39 showed quite fine grain and that prompted me to make it my developer of choice. I still have the magazine around here somewhere. This would be about four to five years ago.

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    Keith,

    You are probably trying to compare granularity?

    There are testing methods described for this, which involves microdensitometry and statistical analysis. It does require good magnification. As the scanner gets higher resolution, one common question I get is whether we can do granularity measurements using scanners, but unfortunately my 6400 dpi scanner isn't good enough for this and still requires microscope optics.

    I can dig up references for granularity measurement but I don't have Practical Photography...

  4. #4

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    Quote Originally Posted by Kevin Caulfield View Post
    I recall a test they did, probably more recently than the one you remember. If I remember correctly they used Delta 100 in the various developers. Paterson FX39 showed quite fine grain and that prompted me to make it my developer of choice. I still have the magazine around here somewhere. This would be about four to five years ago.
    This particular issue was probably around the early 1990`s. I was hoping that someone might know the exact month/year of the issue as I was going to see if I could buy this "back-issue". Paterson Aculux and Acutol came out well if I remember right, but this was before FX39 was introduced.
    Thanks.

  5. #5

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    Quote Originally Posted by Ryuji View Post
    Keith,

    You are probably trying to compare granularity?

    There are testing methods described for this, which involves microdensitometry and statistical analysis. It does require good magnification. As the scanner gets higher resolution, one common question I get is whether we can do granularity measurements using scanners, but unfortunately my 6400 dpi scanner isn't good enough for this and still requires microscope optics.

    I can dig up references for granularity measurement but I don't have Practical Photography...
    This particular method was devised by the PP tester(s) well before D.I. was any where near as popular as today. I guess today that scanning might be a more convenient option. Back then, it was with a 35mm camera attached to a Leitz or Nikon Microscope (I can`t remember which).
    This sort of test was to see subtle differences between different developers concerning granularity and speed yield. FP4 was chosen as a `YARD-STICK` because of it`s popularity in the UK.
    You don`t see test like that these days.
    Cheers.

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    Quote Originally Posted by Keith Tapscott. View Post
    This particular method was devised by the PP tester(s) well before D.I. was any where near as popular as today.
    What's DI? Maybe something scanner related?

    Back then, it was with a 35mm camera attached to a Leitz or Nikon Microscope (I can`t remember which).
    This sort of test was to see subtle differences between different developers concerning granularity and speed yield. FP4 was chosen as a `YARD-STICK` because of it`s popularity in the UK.
    You don`t see test like that these days.
    I look at films developed in different exposure levels, different developer, etc. when I'm testing for a new film or a new developer. At about 400x or higher, you can get quite a bit of information, especially if you combine the visual info in the context of theory of development... and this kind of analysis is common among emulsion scientists. But I don't find microscopic observation to give any insight about speed yield, image sharpness or tonality.

    Image sharpness is better assessed at much lower magnification, like 20x. Better yet, judged from high mag prints.

    Speed and tonality are mainly sensitometric issues that are unrelated to magnification factor.

    You can use a good scanner to do densitometry by calibrating the scanner raw signal output with a calibrated step wedge. Expect quite a bit of nonlinearity. I have my measurement of my scanner, Epson Perfection V700 on my website. Many scanners set the preamp gain in the scanner to be whatever value determined by the scanner or the software, each time you use it. So the best way is to always scan your test specimen and a calibrated density step together and calibrate each time.

    At the end of the day, what matters is the quality of negative you get. Exact measurement of granularity and speed is involved. But you can always judge everything you need from enlargements and you can always give half stop overexposure to make sure you are not losing shadow. I consider anything more is strictly optional for the practical aspect of photography (not the magazine name).

  7. #7

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    Quote Originally Posted by Ryuji View Post
    What's DI? Maybe something scanner related?
    I tend to associate scanners with D.I. and never really thought about the use of scanners to assess the image quality of films, so thanks for that.

    You often see questions posted on the forum asking: "What is the best developer to use?" when processing a particular B&W film, this is usually followed by many answers from different forum members suggesting to use X, Y, or Z developer at a specific dilution etc. Of course, subjectivity plays a key role and many photographers have their own favourite film and developer combinations.
    I remembered reading the film developer review in PP magazine years ago and I wanted to discuss just how the performance of a developer is measured and quantified. How developers are actually tested is something I have not seen mentioned before and is something that I am curious about.
    I shall take a look at your website and thanks for replying.

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    Well, developer is a very personal choice, I learned.

    We can do all sorts of test but then tests are not free from the factors from emulsion side. At the end of the day, the best developer varies depending on what you want, just like wine and whisk(e)y.

    Also please note that I said in my earlier post that even my 6400dpi scanner is insufficient for granularity measurement. It is sufficient for basic sensitometry if you calibrate each time. Scanners are made for practical imaging purposes and they are not made for scientific measurements, so there are some limitations.

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    Dear Keith,

    Microdensitometry for grain and sharpness. It is rare for two labs to get the same figures because of equipment variations but the same lab's figures for different films are an excellent basis for comparison.

    Curve plotting for H&D curve shape

    Sensitometric testing for ISO speed. Should be done with new and aged film. ISO standards also have some 'wiggle room' for rounding, i.e. as long as it's over ISO 80 you're allowed to call it ISO 100 (Fuji Acros in most devs) and as long as it's near enough ISO 200 in ANYTHING you can call it ISO 200 (Fomapan T200 in Microphen or similar -- its speed in every dev I've tried is just about identical to Ilford FP4).

    Fog testing

    Tests for storage life of dev

    And, above all, 'does it look good' -- 'cos if it doesn't, who cares about the rest?

    Cheers,

    R.

  10. #10

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    Quote Originally Posted by Roger Hicks View Post
    And, above all, 'does it look good' -- 'cos if it doesn't, who cares about the rest?

    Cheers,

    R.
    Dear Roger,
    I agree, that some film and developer combinations have a `look` that is aesthetically very pleasant to see. I also think that is the most important consideration to bear in mind when choosing B&W materials.
    Although I don`t use them, developers such as Rodinal and various staining developers are very popular on the forum, probably for that very reason.
    I was simply wondering how the performance of certain products such as developers were measured.
    Thanks to Kevin, Ryuji and Roger
    for replying.
    Keith.

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