Is color print film shot at box speed?

Discussion in 'Color: Film, Paper, and Chemistry' started by stradibarrius, Jul 8, 2012.

  1. stradibarrius

    stradibarrius Member

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    I do not shoot much color print film. Many of the B&W films that I normally use work better for me when shot a half the box speed.
    Is this normally true with color print film too. I am shooting some Porta 400 and wonder if most people shot it at 400 or something less?
     
  2. BainDarret

    BainDarret Subscriber

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    Colour neg film can take a certain amount of over exposure without ill effects. I generally allow about 1/3 stop extra exposure. Try rating it at 320. Under exposed colour neg film can look pretty bad but a little bit of over exposure just seems to pump up the colour. Try bracketing your first roll and see what works.
     
  3. markbarendt

    markbarendt Subscriber

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    Box speed works well for me.

    A bit extra won't hurt but doesn't necessarily help.
     
  4. Diapositivo

    Diapositivo Member

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    You will find a lot of threads in APUG on this subject.

    The not-so-general consensus is that best results are obtained at box speed but overexposure gives a safety buffer, because negative film has much more exposure latitude toward overexposure than underexposure, so by opening a bit (from 0.3 EV to 1 EV) you will capture more shadows without compromising your highlights.

    Somebody will tell you that systematic overexposure of 1 EV will alter the chromatic response of the film. Other will tell you that they don't notice the difference. YMMV.
     
  5. benjiboy

    benjiboy Subscriber

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    I always work on the principal that the film manufacturers know better than I what the speed of their films are, and unless I consistently get under or overexposed results I stick to the boxed speed.
     
  6. j-dogg

    j-dogg Subscriber

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    Kodak is always over-rated, especially Portra, I shoot box speed on new stuff but anything expired over 200 ISO I drop it a 1/3 to 1/2 stop

    Portra, especially the VC and NC variants, not new Portra, looks great at 320 and is more inclined for prints where as new Portra is made for scans.

    All others I do at box speed as long as it is within expiry.......about to do some Techpan at ISO 16, need to find a good tripod lol
     
  7. jayvo86

    jayvo86 Member

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    I like shooting my Portra 400 @200.

    To be the skin looks really good, but that's just me. You can see examples of Portra 400 (35mm) shot at 200 in my gallery.
     
  8. Rudeofus

    Rudeofus Subscriber

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    Be aware that box speed is a selling point, so there is some pressure on manufacturers to be overly optimistic. Supposedly there is a 30% speed difference between developing immediately after exposure vs. waiting a few days. Guess which number the box speed will show ....
     
  9. markbarendt

    markbarendt Subscriber

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    Actually box speed is a well thought out industry standard (iso) with real basis in the facts and the physics involved.
     
  10. Rudeofus

    Rudeofus Subscriber

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    Box speed may well be based on physical facts, but requires a procedure which is rarely followed in practical work. See my point above.
     
  11. markbarendt

    markbarendt Subscriber

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    So the problem is the user. I agree there.

    But those procedures are not tough.

    For example; incident meter, set camera, shoot.
     
  12. benjiboy

    benjiboy Subscriber

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    +1
     
  13. markbarendt

    markbarendt Subscriber

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  15. Diapositivo

    Diapositivo Member

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    Mark, you found it! (I had made two searches without success).

    The test by Stephen Benskin is very interesting indeed. Considering that the box ISO value already incorporates the "speed loss" due to latent image decay, one can say that if the exposed film is kept in the fridge between exposure and treatment the speed loss is basically non relevant.

    The table published by Benskin gives an index of 71 for 7 days (this is incorporated in the ISO measure) and an index of 65 after 31 days. The speed loss of the latent image (6/71) in four weeks out of the fridge is around 8% (around than 0.16 EV if I get it right, which is not guaranteed anyway :unsure: ).
     
  16. markbarendt

    markbarendt Subscriber

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    Took me three trys.
     
  17. nworth

    nworth Subscriber

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    Box speed is usually best, especially with built in light meters. These films are more tolerant to over exposure than underexposure, but the latitude of most of them is pretty great. Overexposure results in a washed out look, evident even with one stop overexposure but not obnoxious until about two stops with most films. Underexposure is a lot like underexposure with black and white - muddy with little tonal range. You will definitely notice a one stop underexposure; at two stops the negative will generally be useless. As I understand it, the speed rating system for color films is a bit different than for black and white, and it gives a speed that better reflects actual practice. Of course, your individual metering and picture taking technique may affect this; so your individual experience with a particular film may vary.
     
  18. AFenvy

    AFenvy Member

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    I often shoot at 1/3 to 1 stop overexposed on my color print film. A lot of it is old, and though it has been cold stored, I try to always be safe just in case it has lost speed due to its age.
     
  19. Derek Lofgreen

    Derek Lofgreen Subscriber

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    I did a little text of my own with some Kodak consumer film. It's not super technical so for all of you super number, science/engineer types it may not help but if your like me and you want to SEE what it looks like when you change ISO settings on film then you can see one example on my blog.

    I always over expose C-41 film from the box speed. I do it because I like it. Some like it really over exposed and some folks not so much. It's really a personal choice more that technical for me.

    Hope it helps,
    D.
     
  20. RPC

    RPC Member

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    But there is more to it than that. One's shutter speeds at various settings, apertures at various settings, meter and metering technique may not be totally reliable, giving one exposure errors when least expected. I believe that unless one has tested these well, then a half a stop to a stop of overexposure is a good idea. This will help insure preservation of shadow detail without compromising highlights as mentioned earlier, for both over- and under- exposure errors, unless the errors are very large.
     
  21. Rudeofus

    Rudeofus Subscriber

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  22. markbarendt

    markbarendt Subscriber

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    The testing you suggest is a good idea, it can be done in just a few frames to get a good feeling of how things are working.

    Leaning toward over exposure as a normal thing though is not a free lunch, it's a crutch.

    The first cost is most likely shutter speed, extra exposure time raises extra risk of blur. I'd much rather have some under exposure than some blur. Blurred images, unless on purpose, are simply trash.

    Then in the enlarger thicker negatives make for longer print times and make it tougher to place/use meters and make it tougher to use the aperture setting that is optimum...
     
  23. benjiboy

    benjiboy Subscriber

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    All I can tell you is it works for me.
     
  24. DREW WILEY

    DREW WILEY Member

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    With current Kodak PRO color neg films (Portra, Ektar) box speed seems to be spot on. But if you
    do make an error, you're better off overexposing rather than underexposing. Siginificant exp errors
    will come with color reproduction issues, however. Amateur films, on the other hand, are marketed
    under the assumption that serious exposure as well as storage issues will be present. Just depends
    how nitpicky you are, unless you're just bending the rules for creative effect. I'm admittedly very
    nitpicky - I want optimum not generalized results, and spotmeter everything.
     
  25. RPC

    RPC Member

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    I have never found any of these to be a problem, and in general I believe the benefits of a little overexposure outweigh any risks.
     
  26. RPC

    RPC Member

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    That's great, it implies everything I mentioned is working for you, but as we know everyone's milage may vary.