Image Emergence Time Multiples

Discussion in 'B&W: Film, Paper, Chemistry' started by dancqu, Jan 15, 2008.

  1. dancqu

    dancqu Member

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    Image emergence time: the time it takes for first
    image appearance. The multiple; I've read it runs 4 to 5.
    The multiple applied to the emergence time equals the time
    needed for complete development. Is that correct? Does the
    multiple vary from paper to paper or is it a safe bet that the
    multiple is a constant whatever the paper? Dan
     
  2. RobC

    RobC Member

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    Use what will be a midtone in the finished print as the emergence point. So what you do is put your first print in developer and measure the time it takes for that midtone to start to emerge. For example 15 seconds. You then let the print continue to completion and take the total print time. For example 3 minutes = 180 seconds. You then divide emergence time into completion time so you have 180/15 = 12. 12 is then your printing factor. Next print you put in developer you measure emergence time of same midtone. Say it takes 16 seconds to emerge. You multiply 16 by 12 (your printing factor) and the result ( 192 seconds) is the total time you leave this print in the developer. Next print may take 18 seconds for mid tone to emerge so total time will be 12x18= 216 seconds. etc etc.
    You must work out new printing factor for each new neg that you are printing and every time you change / replenish developer. Thats the idea. Its very simple to do in practice and should give very consistent prints when doing a batch of the same negative.
     
  3. MurrayMinchin

    MurrayMinchin Membership Council Council

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    As Ansel explained it in his book, The Print, he used an area of textured grey, like grass. He was using Dektol I believe. I use a Glycin developer which is slow off the start but really picks up steam after a minute, so I use the negatives clear edge as the emergence area.

    Sounds reasonable as it just so happens my development factor for normal development is 4.5 :smile:

    That's the idea.

    Nothing is ever a safe bet, but it's easy to test for.

    What I did was use my test negative (one that prints the easiest on grade two paper and has a full range of tones) and made the best straight print I could with fresh developer at my standard temperature and time. Then I took the emergence area's time of emergence (40 seconds) and divided that into the development time (180 seconds) which gave me a development factor of 4.5.

    Now if the developer gets a little cold, the emergence time gets delayed which when multiplied by the development factor compensates for the sluggish developer. If the developer warms up, the opposite happens. You could even change the developers dilution and the new emergence time multiplied by the original development factor will give you a print dang close to, if not the same as the original.

    I sometimes keep my working solution for months at a time and swear by this system for getting consistent results.

    Murray
     
  4. snallan

    snallan Member

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    Hi Dan,

    Whenever I try a different paper, I do a couple of tests to determine the maximum useable development time (the time beyond which chemical fog starts to become apparent during development), and the maximum black development time (the minimum time required for a well exposed black to reach its maximum density). These are then the minimum time a print on that paper should be developed for (max black time), and the maximum time that must not be exceeded when developing a print (max development time). I then select a time for that paper that I will use for complete development, and determine my factor from there; though they generally seem to fall in the 4x - 6x range.

    I don't do the checks every time I get a new batch of paper, but every now, and then, I will recheck the characteristics of a paper.