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  1. #1

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    B&W exposure latitude

    Hello,

    I have another newbie question. Almost everyone keeps saying that B&W is quite forgiving in terms of exposure. What does that actually mean? Does it mean that if the exposure is off a little we can still push and pull it back by developing the negatives differently? Because if thats the case then in my scenario this latitude flexibility will not help me because i am trying to develop the film myself and will only follow strictly to the 'rules'. Help anyone?

    Mark

  2. #2
    2F/2F's Avatar
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    There is a lot you can do to print a b/w negative that is technically flawed. With b/w negs, you have the capability to make extreme manipulations fairly easily, and without having to have a ton of technical skill or experience. That is what is meant by "latitude" when used in a general sense. It's the ability to make use of something that is not ideal by way of various manipulative tools in the darkroom.

    In b/w, there are endless options in developing and printing, unlike with other processes. As far as exposure latitude specifically, and the ability to capture a wide brightness range on the film, I think color negs are superior. But you can do so much more, and so much more easily, in b/w developing and printing than you can with color developing and printing, so it is generally seen as the "easier" medium to work with.
    2F/2F

    "Truth and love are my law and worship. Form and conscience are my manifestation and guide. Nature and peace are my shelter and companions. Order is my attitude. Beauty and perfection are my attack."

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  3. #3
    Steve Smith's Avatar
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    Latitude really refers to the amount you can get an exposure 'wrong' and correct for it at the printing stage.

    Wrong is a bit of a strong word to use as there are also artistic choices but if you produce a negative which is a bit too dense, it can be printed for a bit longer or a light negative can be printed for a shorter time to compensate.

    Transparency film does not have this latitude as the processed film is the finished product.


    Steve.

  4. #4
    polyglot's Avatar
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    Say you underexpose by a stop and don't notice; you'll lose some shadow detail. If you do notice, you can correct by pushing (extending development) and get back a decent image. It will have a little more contrast if you push but you can just print it with a lower-grade filter in the enlarger. You really only get underexposure latitude by pushing, so it's not so much latitude as a deliberate decision to use the film in a different way. Don't underexpose if you can help it; the more light the better with negatives.

    You can overexpose most B&W films by at least three stops (i.e. 8x too long!) without causing any problem except additional grain. The negatives will be very dense but that just means they need to spend a little longer in the enlarger. That over-exposure latitude is what most people are referring to and it means you can select a conservative exposure setting and basically ignore the light levels until they change dramatically. If suddenly you end up with 2 stops more light, the image will still be completely fine for most purposes except the most exacting.

    Slide film with a 2 stop over- or under-exposure will come out nearly clear or nearly black; it'll be useless in comparison to what you can do with a B&W shot.

    Modern C-41 (colour neg) has as much overexposure latitude as B&W but it's more difficult to recover from because the saturation generally reduces with overexposure and some colours can go wonky, which is hard to correct for using only analogue techniques.

  5. #5
    ic-racer's Avatar
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    1) Film speed and development are independent
    2) ISO exposure is the minimum exposure needed for a quality print under controlled conditions.
    3) There is no ISO standard for the maximum exposure tolerable to make a quality print...therefore
    4) There is no ISO standard measure of film latitude
    5) Most all contemporary B&W films will exceed the range of the common 21 step wedge...therefore
    6) It is somewhat difficult to have a meaningful discussion of B&W film latitude

  6. #6

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    Thank you all so much. Now i feel much better. I guess in a nutshell, i should err on the side of overexposure rather than underexposure. At least then i know that i have the raw data that if anything could be 'corrected' at the printing stage. This is wonderful.

    Another side question is, digital black and white obviously does not have this latitude right? I used to take color shots in my D200 RAW and convert it to B&W. Is it correct to say that the dynamic range for digital is not as many stops as the film's B&W? If thats the case then would it be right to say that in this one area film is definitely better than digital??

    Mark

  7. #7
    RalphLambrecht's Avatar
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    Quote Originally Posted by mingaun View Post
    ... I guess in a nutshell, i should err on the side of overexposure rather than underexposure. ...
    Correct, when in doubt overexpose and underdevelop! B&W film has a huge latitude towards overexposure (10 stops and more) and almost none towards underexposure (see ice-racer's comments).

    Quote Originally Posted by mingaun View Post
    ... Is it correct to say that the dynamic range for digital is not as many stops as the film's B&W? ...
    Yes, digital is currently limited to an overall dynamic range of 9 to maybe 11 stops, but we don't discuss digital on APUG.
    Regards

    Ralph W. Lambrecht
    www.darkroomagic.comrorrlambrec@ymail.com[/URL]
    www.waybeyondmonochrome.com

  8. #8
    polyglot's Avatar
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    While B&W negative has overexposure and very little underexposure latitude, digital is the opposite. You can correct nearly any underexposure on digital but no overexposure.

  9. #9
    RalphLambrecht's Avatar
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    Quote Originally Posted by polyglot View Post
    While B&W negative has overexposure and very little underexposure latitude, digital is the opposite. You can correct nearly any underexposure on digital but no overexposure.
    True, in this regard, digital is similar to slide film.
    Regards

    Ralph W. Lambrecht
    www.darkroomagic.comrorrlambrec@ymail.com[/URL]
    www.waybeyondmonochrome.com

  10. #10

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    If you underexpose with digital you end up with noise (or nothing) in the shadows. Shooting B&W film is much easier... make sure you have sufficient exposure and you'll end up with something printable.

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