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  1. #1
    bmac's Avatar
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    There has been a little discussion about this meathod of printing. Can someone give a bonehead sleep deprived new dad a basic explanation?
    hi!

  2. #2

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    There are two ways to measure exposure, one by the amount of time the paper is exposed and the other by the amount of light the paper is exposed to. In the f stop methid you keep constant the time and you vary the "amount" of light. I tried it and found very confusing and complicated. Since I am old school I learned to judge manipulations by time...ei, lets burn 3 more sec here, dodge 5 sec there....for the life of me I could not figure out what a 1/4 f stop would do....but some people seem to like the method.

  3. #3

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    If you can find a copy of Eddie Ephraums "Creative Elements- Darkroom Techniques for Landscape Photography", he goes into depth about using this method and includes an F.Stop exposure table which allows you to determine time in 1/4 stops. Of course this asumes that you are using a timer that can operate in tenths and hundreths of a second.

    It is really much more precise, and as you use it you begin to look at test strips and prints and it bcomes easy to determine burning and dodging times and adjustments in exposure.

    I believe it is still available there was a timer called a Nocon that could be programmed to adjust the exposure time based on initial time and the desired f-stop change that was entered.

    More modern F-stop timers adjust can adjust the light as well as the time.

    I use the more cumbersome method of going to the table and inputting the new time in a digital timer. The formula is also in the book.
    "Fundamentally I think we need to rediscover a non-ironic world"
    Robert Adams

  4. #4
    Les McLean's Avatar
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    RH Designs, a UK company, manufacture an excellent fstop timer that is simple to use and offers a dry down factor, two channels for split grade printing and a compensating feature for those who use cold cathode enlargers. I have used this companies products since the mid 90's and can certainly recommend them
    "Digital circuits are made from analogue parts"
    Fourtune Cookie-Brooklyn May 2006

    Website: www.lesmcleanphotography.com

  5. #5
    ann
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    Several years ago I began teaching my students to burn and dodge using the conspect of f stops. This is how our cameras work and it seemed logical to use the same logic in the darkroom. i.e. in the field with snow we open up 1 to 2 f stops to insure we had white snow, not gray. White highlights on a print would be burned down using the same logic. Paper white highlights would reguire about 2fstops more light than the inital exposure to bring them to middle gray. How much is an artistic decision.
    It may sound more involved than it really is, once people start thinking that way it is amazing how quickly they catch on.
    Check out Eddie's book, if I remember Tim Rudman also talks about f stop printing in his Master Photograhpers book. ( I thought I was so clever, until i found out in Europe they make a timer and this method is not so strange). Works just as easily with dodging.
    The biggest stumbling block is doing the math in your head, however, after awhile it becomes second nature.
    http://www.aclancyphotography.com

  6. #6

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    Time for my two-cents worth: I have for years used a hybrid of the f-stop and time methods: I figure exposures by percentages. For me, the log and square-root-of-2 calculations that one has to do for the f-stop method are superfluous. I find it much easier to alter exposure and figure dodging and burning by increasing or decreasing exposure by a percentage. Of course, a 100% increase is a one-stop increase. Conversely, a 50% decrease is a one-stop decrease. Intermediate values are easily figured, and with just a little practice, one learns to estimate the effect of, say, a 10% decrease in exposure.

    Test strips can be made to approximate, for example, a progression of 20% increases. For example, 10 sec. (+20% =), 12 sec. (+20% = approx), 14 sec. (+20% = approx.), 17 sec. (+20% = approx.), 20 sec.... etc. Ten per cent strips are just as easy to figure. No logs, no square roots, no problems. I use a metronome as a printing timer and, when making the above test strip, would simply count 10 sec, cover the first stripe, count 2 sec., cover the next stripe, count 2 mor sec., cover the third stripe; count 3 sec..... The progression is then 10+2+2+3+3+4+5.... Easy to remember, and, if need be, post close to the enlarger for reference.

    This method is also extremely helpful when making a different size of a print already made. Once the basic exposure has been arrived at, all manipulations can be converted to percentages and refigured for the new print. If the original print has a basic exposure of, say 30 sec. and I burned an area for 6 sec., that would be 20%. If the new print has a basic exposure of 20 sec., then 20% of that would be 4 sec. Easy

    Frankly, I'm surprised people go to all the trouble of figuring, making charts and computer programs to compensate for the unwieldy f-stop numbers and the inverse square law when simple percentages accomplish the same thing with a minumum of calculation. After all, it is the final image we are interested in, right...

    Regards, ;^D)

  7. #7

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    I have an article about this at http://unblinkingeye.com/Articles/TestExpo...o/testexpo.html, giving values for 1/4-stop intervals, but I only find it really useful for exposures above 20 seconds.

  8. #8
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    Thanks for the link Ed. I am getting about 35 sec main exposures on my D2 with a El Nikkor at F11 making 11X14 prints from 6X7 negs...
    hi!

  9. #9

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    I second the recommendation for RH Designs f-stop timer, its a pleasure to work with... Yes, Tim Rudman does speak about his use of this method in his book and on several other photo forums...in addition Robert Mann also discusses a version of this method on his <www.parisdarkroom.com> site. For me it has always made more sense to think in terms of f-stops, and with the introduction of the f-stop timers life is much easier for me in the darkroom.

    LD Horricks
    Prague, Czech Republic
    LD Horricks
    Prague,Czech Republic

  10. #10

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    Robert Mann&#39;s site is www.parisdarkroom.com

    For some reason my prior post didnt include thid info even though I typed it in...maybe because of the parenthesis I used...I&#39;m a computer luddite.
    LD Horricks
    Prague,Czech Republic

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