Color Test Print (newbie question)

Discussion in 'Enlarging' started by markwny, Apr 14, 2008.

  1. markwny

    markwny Member

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    I'm just getting started in color printing and would like some advice. I've read multiple books on the "theory" of color printing and two processes, not to be confused with additive and subtractive processes, seem to be prevalent. The first process discusses making a test print by varying the exposure time with a mask and keeping the lens aperture constant. There are variants on this theme as to the amount of time for each strip, but the concept the same. The second process that I have found makes a test print with each strip having the same exposure time, but with a different lens aperture setting.

    I'd like some advice as to the pros and cons of each method and which one is more prevalent.

    Thank you in advance,
    Mark
     
  2. Nick Zentena

    Nick Zentena Member

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    Paper has or had recpricoity problems if times got too short or too long. So varying the aperture avoided this. I don't think it's any issue with normal modern papers. I know I've used a fairly wide range of times.
     
  3. markwny

    markwny Member

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    Thanks Nick. That makes perfect sense.
     
  4. john cowie

    john cowie Member

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    When I learned color printing I was told the exposure HAD to be 4 secs. So I learned to just adjust my exposure by the aperture. This worked for the most part but as we all know sometimes I had to use 5,6, etc secs. and it was only when I got over 7-8 that the color shifted. It wasn't the big shift that would bring the building down that my boss envisioned. Just adjust for it.
     
  5. Terrence Brennan

    Terrence Brennan Member

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    Try and make your initial tests by varying the aperture. You could try something like 10 seconds, with an f/stop range of f/4 to f/16. Any decent lens will have a reasonably consistent change from f/stop to f/stop. Avoid older lenses, especially those which don't have click stops, or the really old ones which don't have a consistent spacing between f/stops. Don't use an aperture between f/stops, unless it is also click-stopped; you'll never hit the same spot twice.

    The trick here is to pick a negative which is truly representative of your average shooting conditions. If you shoot mostly, say, under daylight, don't use a negative which was exposed to a mix of tungsten and fluorescent light! You can make a series of negatives, which were exposed under the typical conditions you might use when photographing. You could have a daylight exposure, a tungsten exposure, a fluorescent exposure, a mixed lighting exposure, et cetera.

    A good idea would be to make an exposure of series of exposures, with a flesh tone and a gray card. Avoid colour bars, or Macbeth Color Checkers, as the colours are somewhat too saturated to make a judgement call on colour balance. The flesh tone and gray card should be adequate.

    Make a range of exposures, from about three stops under to three stops over. Measure the gray card densities using a calibrated densitometer, and compare them to the maufacturer's specs. If you don't own a densitometer--most photographers don't--ask the manager of the laboratory where you have your colour film processed if you can use theirs. You can also pick and "over" and "under" negative for future comparison. I assume you don't process your own film; that's a mechanical operation best left to a laboratory.

    Use the same film stock, preferably from the same emulsion number, for your test, as you purchase for day-to-day use. Yes, it DOES matter; if you haven't the financial wherewithal to buy a large stock of film of one emulsion, when you buy film, bring a carton of the old film and ask for the same emulsion number.

    If you want further information on this subject, drop me a PM.
     
  6. 2F/2F

    2F/2F Member

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    I enlarge in aperture priority mode, personally. :smile: I pick an aperture right in the middle of the available range of apertures, where most lenses are usually at their sharpest. Once you have done one reference print, you know what times will get you close for that size of print, and can know where to start by simply looking at the density of the neg. If times get uncomfortably long or short (almost never unless printing a screwed up neg.), then I adjust aperture.

    It is true that using apertures to alter exposure is more accurate. However, you don't need accuracy in a trial and error process like printing. You need accuracy if using measurement tools like a light meter when shooting, but not with printing, where you adjust everything by eye and by tests. All you need is repeatability. Reciprocity failure doesn't make a difference, as long as it is the same amount of reciprocity failure each time.

    All that matters is that you develop a system that works for you and gets you the prints you like. It's just like shooting with your camera. You decide whether to vary aperture or time to get your exposure.

    2F/2F