can you push/pull iso on individual frames?

Discussion in '35mm Cameras' started by Mike Henley, Jun 8, 2004.

  1. Mike Henley

    Mike Henley Guest

    I was reading past usenet threads and some say that you can only
    push/pull for a whole film rather than for individual frames "on the
    fly". Is this true?

    Say for example you have an aperture-priority semi-manual camera where
    you set the aperture and the camera chooses the shutter, and you have
    no direct control over the shutter, can you not deliberately
    overexpose or underexposre some images by using the iso dial? also, if
    this is possible, what would equate with EV+1 or EV+2 or even EV-1 or
    EV-2 if you're using iso dial on a 400 film for example (or a 100
    film)?
     
    Mike Henley, Jun 8, 2004
    #1
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  2. Mike Henley

    Photodad Guest

    I'll try to be less controversial with this reply. ;)

    Obviously, you can not push process an individual frame (talking film
    processing here, not printing). However, most modern films have enough
    latitude that you could go EV+2 on the critical frames, have a good quality
    processor (not your normal lab) push the whole roll EV+1, and probably be OK
    with all frames. The results will vary depending upon the film you're
    using.

    But don't try this with standard processors, like Walmart's photo lab, who
    will say they know what you're talking about, then process as normal because
    they really have no clue. (Yes, that's experience talking - don't ask.)

    If in doubt, film's cheap. Just waste the rest of the roll and put another
    roll in. I now keep 12 exposure rolls around for just this problem.

    In addition, a good quality processor that reads each frame before printing
    can help the process as well. Most cheap labs read the first frame and
    expose the whole roll on the basis of that reading. If your first frame is
    of your shoes or the like, your whole batch of prints can be a mess.

    Now, if you do your own processing, you're in great shape!

    Walt
     
    Photodad, Jun 8, 2004
    #2
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  3. Mike Henley

    TP Guest

    Yes. The only exception is where you are using a film with great
    latitude, such as Ilford XP2 Super, when you can expose individual
    frames at a range of ISOs from 100 to 1000 - the film's nominal rating
    is ISO 400.
    Yes, that is possible. A change of EV 1 would be achieved by halving
    or doubling the ISO setting on the camera. With ISO 400 film,
    underexposing by 1 stop would be achieved by setting the film speed
    dial to ISO 800. Two stops of underexposure would be ISO 1600.

    One stop of overexposure would be ISO 200 and two stops ISO 100.
     
    TP, Jun 8, 2004
    #3
  4. Mike Henley

    Alan Browne Guest


    You can EI every frame as you see fit. For example, a common
    practice with Portra 160 is to EI it as ISO 100. But without
    'pushing' the development.

    When it comes to development (where the "push" occurs) it is
    mighty hard to isolate the frames to give them different time in
    the developer, so normally the whole film is pushed. ('pull' is
    not practiced very much).

    Side note: Some photographers do 'clip' processing of their slide
    film where the first frame or two is developed at a specific
    setting, and then depending on those results, the development is
    adjusted for the remainder of the film(s).

    Yes, you can change the exposure through the ISO setting. On a
    full featured camera, however the practice is to rate the film
    with the ISO setting; and control individual frame exposure (or
    rather meter correction) with the EXP COMP dial. In the absence
    of EXMP COMP, using the ISO is a good standby, however you need
    to be always sure that you are bringing it back to the correct
    setting.

    Doubling the ISO setting is the same as -1 stop (-1 EV) of
    exposure, AOTBE*.

    Halving the ISO is the same as +1 stop (+1 EV) of exposure, AOTBE.

    AOTBE = All other things being equal.
     
    Alan Browne, Jun 8, 2004
    #4
  5. Mike Henley

    Bob Hickey Guest

    film at 200 is a 1/3 push. Bob Hickey
     
    Bob Hickey, Jun 8, 2004
    #5
  6. (Mike Henley) wrote in
    As others have hinted but not outright said, unless I missed it, the
    terms "push" and "pull" refer not only to how the film is exposed, but how
    it's developed too.

    Changing exposure on a frame is simply, "changing exposure on a
    frame." This doesn't necessarily mean you're trying to rate the film at a
    different ISO, it only means you don't agree with the camera's meter. And
    there are lots of times when you should do that, really.

    Push or pull processing means you're treating the film as an entirely
    different ISO, and need to change development times or temperatures to
    reflect that. It's a two-step process, and far more useful in slide film
    where there's no extra step of printing to make adjustments within, and
    where the film latitude is narrow enough to warrant it. You might also do
    it because it gives different results than straight processing, changing
    contrast, saturation, and sometimes color cast.

    So on the individual frame, no, not in the strict definition of
    "push" or "pull". Impossible to process.

    But as others have said, there are similar situations where you can
    change exposure for very good reason. Because the meter is fooled by
    elements in the frame (i.e., lots of sky and water), because you're after
    more shadow or highlight detail, because you want the print tweaked during
    its own exposure, or because you disagree with the rated ISO of the film
    and like the results better at slight under- or over-exposure. None of
    these are pushes or pulls, per se, but still have valid uses.


    - Al.
     
    Al Denelsbeck, Jun 8, 2004
    #6
  7. Mike Henley

    Gordon Moat Guest

    Push and pull actually refer to processing of film. That is done usually
    by changing time, or temperature, or both, when processing the film, and
    needs to be done an entire roll at a time.
    Sure, but the exposure compensation is exactly that, a slight variation
    of exposure. Using a negative film, you could go fairly wide in
    compensation settings, and still get printable images. With transparency
    (slide) films, you can rarely ever go more than one stop and still have
    much of a usable image, unless you are going for an unusual effect in the
    final image.

    One reason to push a film is for low light usage. Another reason to push
    a film is to increase the apparent contrast in the final results. Pulling
    a film is sometimes done to soften, or reduce contrast, in the final
    results. Both of these processing options always costs more.

    You could do portions of a roll of film that way, though likely you would
    want a snip test done (extra $$). Even with that, it would mean guessing
    where to cut the film strips (loosing some frames), and involve hand
    processing of the strips. I have seen people do this, but I think the
    added time and expense are a waste.


    <http://www.agstudiopro.com> Coming Soon!
     
    Gordon Moat, Jun 8, 2004
    #7
  8. Mike Henley

    Alan Browne Guest

    It's a pull if you shorten the processing.

    If you simply "rate" it at 100 (v 160) it is just consistent over
    exposure of all frames.

    Cheers,
    Alan
     
    Alan Browne, Jun 8, 2004
    #8
  9. If I am early in the roll....say, somewhere in the first 12 frames, and I
    have to push the film speed for something I want, then I will probably push
    the whole rest of the roll and forego the first dozen fromes. (I usually
    shoot slide film, so the non-pushed frames will be ruined), If the earlier
    frames are important to me, I will rewind that roll, leaving the leader out,
    and put in a new roll for the pushed shot.......
     
    William Graham, Jun 8, 2004
    #9
  10. Mike Henley

    Sabineellen Guest

    If in doubt, film's cheap. Just waste the rest of the roll and put another
    12 exposure rolls may be cheap if you develop your film yourself, but when i
    wanted a 12 exposure roll processed they charged me the same up as up to 27
    exposures. (apparently the menu option for the 24 exposure roll, the only other
    option was up to 40 for 36 exposure roll)
     
    Sabineellen, Jun 9, 2004
    #10
  11. You CANNOT push film. It doesn't work.
     
    Michael Scarpitti, Jun 9, 2004
    #11
  12. Mike Henley

    Alan Browne Guest


    Get your film processed at a proper minilab where they can count.
     
    Alan Browne, Jun 9, 2004
    #12
  13. Mike Henley

    Alan Browne Guest

    Do it all the time. Works fine.
     
    Alan Browne, Jun 9, 2004
    #13
  14. Mike Henley

    Lee C Guest

    (Michael Scarpitti) wrote in
    Most of the information I've read stipulates that developing time is
    affected when pushing or pulling your exposure. The problem would be
    extending / decreasing the development time for a single frame. If you
    can solve this problem I'd love to hear the solution.
     
    Lee C, Oct 2, 2004
    #14
  15. If you were desperate you could use the first half of the film at one
    ISO rating, and the second half at another, leaving a few blank frames
    in the middle. Then cut the film in the darkroom and process each half
    separately.

    I do however struggle to think of a single reason why you would want to
    do this, I suppose it is just possible to imagine that you had exposed
    the first half of your last roll at ISO100, then had an unexpected
    one-off opportunity in the dark (whoa, steady now..) which required a
    higher speed. It might happen to one photographer in a hundred once in
    his lifetime.

    You should carry more film - or use 5x4 and process each picture
    individually.

    David
     
    David Littlewood, Oct 2, 2004
    #15
  16. .......Or buy a digital camera.........
     
    William Graham, Oct 3, 2004
    #16
  17. Mike Henley

    Alan Browne Guest

    Individual frames no. You can do 'clip tests' where early frames on a roll are
    developed to test the film and indicate further processing adjustments for the
    rest of the film. Ha$$le.

    Cheers,
    Alan


    --
    "There is no such thing as inaccuracy in a photograph.
    All photographs are accurate. None of them is the truth."
    -Richard Avedon
    -- rec.photo.equipment.35mm user resource:
    -- http://www.aliasimages.com/rpe35mmur.htm
    -- e-meil: there's no such thing as a FreeLunch.--
     
    Alan Browne, Oct 3, 2004
    #17
  18. Mike Henley

    Bob Hickey Guest

    Most of the information I've read stipulates that developing time is
    There used to be a technique where you could push developed film in selenium
    and pull it in farmers reducer. I never had much faith in the whole idea
    though. Bob Hickey
     
    Bob Hickey, Oct 5, 2004
    #18
  19. The technique is one of desperation for correcting serious mistakes on
    vital shorts - not something to be used as a matter of choice. Some of
    the chemicals used are very toxic. See Anchell's "Darkroom Cookbook" and
    other works.

    David
     
    David Littlewood, Oct 5, 2004
    #19
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