Metering for color negative film

Discussion in 'Color Film Discussion' started by Amin Sabet, Apr 4, 2015.

  1. Amin Sabet

    Amin Sabet Administrator

    141
    Mar 22, 2015
    Amin Sabet
    My brother @bijansabet@bijansabet sent me this link: http://www.johnnypatience.com/metering-for-film/

    "Because color negative film usually gives the most pleasant results when overexposed, a lot of film photographers rate their film at half box speed (ISO 200 instead of ISO 400) and expose for the shadows, which results in 2-3 stops of overexposure."


    Is this the way to go? I've always rated color film at the box speed and shot away.
     
  2. pdh

    pdh FF Regular

    31
    Mar 25, 2015
    UK
    well ... you might be interested to know that a very eminent former Kodak photographic engineer shoots all his colour negative film at one-third of a stop over.
    remember also that almost all negative stocks (colour or black and white) can - by design - tolerate at least two stops overexposure with normal processing.
    the question is ... why do manufacturers test their films to be shot at their stated ISO speed (especially with a standard no.variation process like c41) if in fact they are a stop slower?
    if you want, try shooting a roll at box and a roll one stop over exposed and send them off for processing ... then compare the difference.
    if you look at properly made wet prints, you are unlikely to see a difference.
    if you look at scans, you have just introduced anothe factor that makes the judgment doubtful.
    if you look at prints that have been made of scans ... well, you know where I'm going with this I'm sure ...
     
  3. trisberg

    trisberg FF Regular

    32
    Mar 24, 2015
    Thomas Risberg
    I think it really depends on what you are looking for. Are you looking for the absolute best IQ out of your film or are you shooting to capture a moment? I tend to shoot at box speed since I'm always shooting handheld and benefit from faster shutter speeds. On the other hand, I'd rather expose a stop over than under with negative film, but I usually don't sweat it too much since I'm mostly shooting to capture a moment.

    -Thomas
     
  4. pdh

    pdh FF Regular

    31
    Mar 25, 2015
    UK
    I don't think that it depends on either of those things.

    "iq" just seems to be something people chase without having any objective criteria.

    the reason why I am extremely sceptical of web "experts" who say things like "shoot at half box speed for best results" is that there are far far more variables involved than just the ISO you meter by that will affect the final image .

    the accuracy of your meter (whether handheld or in camera), the accuracy of your shutter speeds, the age and initial quality of the film you expose, the temperature at which and developer in which you develop the film, and so on and so forth.

    if you are then scanning there's a whole other mess of worms.

    this is NOT to say that results are random , just to say that there are more variables in play than just what ISO (EI)you shoot at
     
  5. Amin Sabet

    Amin Sabet Administrator

    141
    Mar 22, 2015
    Amin Sabet
    The question is this: If you have a very accurate handheld meter and meter for the shadows, your shutter speed accuracy is very high, and you are using brand new highest quality color negative film and sending it to the best professional lab you can find for developing and scanning, is it generally advisable to rate the film at lower than box speed? I've never done that, and it struck me as an odd recommendation.
     
  6. pdh

    pdh FF Regular

    31
    Mar 25, 2015
    UK
    Nope, box speed is just fine under those circumstances.

    And fine under just about any other circumstances too! :)
     
  7. trisberg

    trisberg FF Regular

    32
    Mar 24, 2015
    Thomas Risberg
    A lot of people I've talked to recommend exposing Tri-X at 320, and I heard this well before we had the internet and web "experts". So, it's not a new thing. Box speed is just a starting point IMO. When I used Kodachrome 64 I always exposed it at EI80 instead of the box speed of 64 just because I liked the results better. It doesn't hurt to experiment with a roll.
     
  8. pdh

    pdh FF Regular

    31
    Mar 25, 2015
    UK
    And long before "web experts" a lot of bullshit was talked as well by people in camera clubs and pubs and bars. There is a whole subculture of mystification of film - actually, photography generally, not just film - and what one should and shouldn't do and doing it right and doing it wrong that really irritates me. This tendency has been around as long as photography has too, so I'm not just some sort of old fart moaning about how "the internet" has ruined everything*

    You can do photography in as simple or a complex way as one likes to make it, but it won't make one's photographs any more interesting or compelling.

    Kodachrome is a good example where many people did shoot it under by a stop or two, but there's nothing like it available today and the whole engineering and processing of Kodachrome was amazingly complex, so it's unsurprising that one had to tweak it a bit ... It is to some extent true of the few remaining colour transparency films that one can do quite a lot to their colour and tonal response simply by (mostly) rather underexposing them, but that's really a consequence of the nature of the reversal process and isn't shared by negative films.

    Modern negative films are amazingly robust in terms of latitude available and miracles of chemical and process engineering. There's a school of thought (mostly of photochemists who have actually been involved in film design and production) that modern films are so good that much of the photographic lore that is still bandied about and passed on as written in stone simply doesn't apply to the films we can buy now.

    It is in anyone's interest to do a simple bit of testing with a roll or two to establish a "personal EI" - it'll allow you to compensate for any or all of the variables I mentioned above plus a few more I haven't.

    The whole business of testing for EIs really only matters when one is wet printing. As far as producing negatives for scanning goes, the scanning process allows for a multitude of exposure and processing sins to be forgiven in the digital darkroom.

    But there is no reason for anyone to just decide that, based on nothing more than what someone else says, they "should" shoot at a different EI from box speed.




    *I'm actually a middle-aged fart
     
  9. Luke

    Luke FF Rookie

    11
    Mar 24, 2015
    Luke
    Well, when one doesn't have your vast knowledge and understanding, one can only guess that a random "web expert" (which I shall, from this point on, refer to as a webspert :laugh1:) might have a better idea about how to properly expose a roll of film than oneself.

    Of course, it's not right. But in some ways it's not really any more "wrong" than just exposing at the "proper" speed.


    But more than anything else, I want to thank you Paul, for giving me a big laugh for that "middle-aged" fart line.
     
  10. trisberg

    trisberg FF Regular

    32
    Mar 24, 2015
    Thomas Risberg
    I absolutely agree with this. It is all about personal preferences and you have to test and determine for yourself what is "best" for you.

    And like you say, scanning introduces a whole other layer on top of the exposure and film processing.

    -Thomas
     
  11. Jloden

    Jloden FF Rookie

    18
    Apr 4, 2015
    Jay Loden
    Too funny, I just read the same post the other day and found it very interesting and informative. Of course that then led to a couple hours of researching and reading different articles and comparisons of exposure latitiude. :p

    My takeaway from this article and the follow up reading I did was twofold: 1) color negative film can be surprisingly forgiving. 2) you can rate film at different EI numbers within a fairly large range without push and pull processing, for *creative effect*.

    I would liken it to creative exposure control where it's not necessarily worse/better/best, but about creative intent. Using porta as an example from the article, if you like your color shots saturated, open, and airy with more shadow detail, you can expose a stop or two above box rating. But looking at the example shots in that article as well as others I'd say it's definitely a subjective evaluation each photographer should make for themselves.

    Upshot of all this is I don't feel so dumb anymore for accidentally overexposing several portra 400 shots in the studio the other week when I misread my own film back and thought it was ISO 100 instead... LOL :D
     
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  12. Jloden

    Jloden FF Rookie

    18
    Apr 4, 2015
    Jay Loden
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  13. Amin Sabet

    Amin Sabet Administrator

    141
    Mar 22, 2015
    Amin Sabet
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  14. pdh

    pdh FF Regular

    31
    Mar 25, 2015
    UK
    Well you really ought to take what I say with as big a pinch of salt as any other webspert (that term sounds vaguely off-colour to me, though) ... but if you are going to choose a speed to shoot at, why not start with the manufacturer's suggestion than anyone else - they are far far more likely to know than the random web expert.


    which is what the manufacturers' data sheets all say about their own negative films - a stop under or up to two and a half over, generally speaking
     
    Last edited: Apr 5, 2015
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