Black and White film latitude ?

Discussion in 'Darkroom Developing and Printing' started by Robert Whitehouse, Jan 11, 2004.

  1. We all know that colour negative film has much greater latitude than
    reversal (slide) film, but where does your typical black and white negative
    film stand in this ?

    Is it closer to colour negative, or colour slide, from a latitude
    perspective ?

    Robert Whitehouse, Jan 11, 2004
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  2. Robert Whitehouse

    Frank Pittel Guest

    : We all know that colour negative film has much greater latitude than
    : reversal (slide) film, but where does your typical black and white negative
    : film stand in this ?

    : Is it closer to colour negative, or colour slide, from a latitude
    : perspective ?

    It depends on the film and to a lesser extent the developer and scene contrast.

    I've found that with Tmax100 I've been off by more then a couple of stops and
    have ended up with very printable negatives with good shadow detail and contrast.


    Keep working millions on welfare depend on you
    Frank Pittel, Jan 11, 2004
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  3. Define the latitude you need. Are we talking under or over exposure?
    Most BW fims handle overexposure well or shall we say well enough.

    Underexposure not well at all.
    In terms of the range of stops the film can represent given normal development
    it depends on the developer, and the amount of exposure. Some have less than
    five and some more than seven. Personally I like more than less.
    Gregory W Blank, Jan 11, 2004
  4. Robert Whitehouse

    Paul W. Ross Guest

    I would say a couple of stops either way. I have a 4x5 pinhole camera,
    and have to take somewhat of a wild guess on exposure and then develop
    by inspection <gasp> with a peek now and then with a dark green
    safelight. I can get a quite printable negative 90% of the time. This
    is with Plus x, tmax100, and the ASA 25 stuff - tech pan.

    With my Retina IIa, I often don't bother with a light meter. Just use
    the "sunny 16" rule and bracket the exposures.

    It is disgusting how much latitude there is in B&W film.
    Paul W. Ross, Jan 12, 2004
  5. You should be able to get accurate exposures even with a pinhole camera. (I
    also have a 4x5 pinhole camera, among other sizes.) You just need to know the
    relative aperture, which you can easily compute from the size of the pinhole
    and its "focal length" (distance from film):

    rel. aperture = focal length / pinhole dia.

    (Technically not absolutely correct, but close enough for jazz.)

    Most pinhole cameras will be somewhere in the f/100-f/400 range.
    David Nebenzahl, Jan 12, 2004
  6. Robert Whitehouse

    Tom Phillips Guest

    Some years ago I produced a how-to on pinhole cameras. Here's a brief
    chart on pinhole f stops and how to estimate exposure.
    Tom Phillips, Jan 12, 2004
  7. Robert Whitehouse

    GP Guest

    The problem usually is knowing the diameter of the pinhole. There are
    several ways to do it (using an enlarger, a microscope, a slide projector,
    etc). Some years ago I wrote about how to measure it using a cheap flat bed
    scanner, here is a link to to that small article:

    GP, Jan 12, 2004
  8. Well, since you broached the subject, I found the easiest way to be by viewing
    the pinhole with a microscope. I just happen to have a microscope I picked up
    at the local recycled-goods store for about $5; plenty good enough to get a
    good look at the pinhole. I also have a couple of "gauges", which are nothing
    but small lengths of wire (guitar strings) with handles: one is .010", the
    other is .009" (smallest strings made). I focus on the pinhole, then stick the
    "gauge" next to it (takes steady hands), then guesstimate the size of the hole
    from the gauge. I figure I'm easily within .002" this way.

    My latest pinhole was less than .009" and almost perfectly round.
    David Nebenzahl, Jan 12, 2004
  9. First, lets defind "latitude" so we are on the same track. Latitude
    is the range of exposure possible without changing the tonal rendition
    of the film.
    The ISO method of measuring speed for B&W still negative film
    yields about the minimum exposure which will give good shadow detail.
    The reason for this is that thin negatives tend to be a little sharper
    and a little finer grained than denser ones. This is mostly of
    interest to 35mm users. As a result there is little latitude for
    underexposures and a great deal for overexposures. Underexposure
    latitude is no more than a stop without noticable loss of shadow
    detail. OTOH, some films will take as much as ten stops overexposure
    and still record a full range of scene brightness, though you may need
    an arc light to print them.
    Because the shape of the toe region of the characteristic curve
    affects shadow contrast some films look better if given a bit more
    exposure than the ISO method indicates. The ISO method does not take
    into account the toe contrast as did the old Kodak method. However, it
    is much easier to measure.
    Most films will yield a bit better shadow detail if given a stop
    more exposure than the ISO speed indicates.
    Color films are processed using highly standardized methods, not
    true of B&W negative film. The methods prescribed in the ISO standards
    for color films is different from those for B&W negative. Color
    negative film in theory has as much latidude as B&W negative (after
    all that is what it basically is) but other problems occur with
    tracking of the various emulsion layers, etc., so the practical
    latitude is less. Nonetheless, modern color negative films will
    tollerate considerable exposure error and still give acceptable
    Reversal processes, including color transparency materials, are much
    more critical of exposure. This is partly because the exposure must
    leave enough silver halide to produce the final positive image (even
    when it is only an intermediate as in color film). The other, and
    probably more important reason is that reversal films are generally
    much higher in contrast than negative materials so that they are
    suitable for viewing by projection of back illumination. This high
    conrast requires a much greater range of densities than are
    encountered in negative materials. Transparency materials probably
    have less than one stop either way for optimum quality.

    Richard Knoppow
    Los Angeles, CA, USA
    Richard Knoppow, Jan 12, 2004
  10. Robert Whitehouse

    GP Guest

    Steady hands is something I don't have. I also use a microscope, mine has
    measuring capabilities in 0.001" and I can easily guesstimate 0.0005" and
    even 0.00025". This microscope is the one IBM CEs used to measure the
    thickness of the stream of ink of an ink jet printer during the 80's.

    GP, Jan 12, 2004
  11. Latitude of B&W film is as high as color negatives.. The highest latitude
    is found in the chromogenic B&W, such as XP2, TCN400, etc...
    Dennis O'Connor, Jan 12, 2004
  12. Robert Whitehouse

    jjs Guest

    In critical practice, B&W has one stop lattitude on either side of the
    correct exposure. That means if you meter correctly (and know _how_ to meter
    correctly), and develop to a standard you can screw up one stop. If you mean
    how long a range can B&W capture, then it depends upon your needs - how
    critical they are, how you print, and so-forth.
    jjs, Jan 12, 2004
  13. Robert Whitehouse

    John Guest

    John, Jan 12, 2004
  14. Robert Whitehouse

    GP Guest

    Got one! Here is a pinhole taken, pinhole enlarged image:

    Have done it only once just to satisfy couriosity, looong exposures, hours!!

    GP, Jan 12, 2004
  15. Maybe you need to cut back on your drinking. (Just kidding.)
    Shoot, now I'm jealous!
    David Nebenzahl, Jan 12, 2004
  16. Robert Whitehouse

    brougham5 Guest

    Closer to color negative.

    You can make a mediocre print from a negative that's been overexposed by 3
    stops (or so) or underexposed by 2.

    Like everything, there isn't a magic silver bullet. For any given image
    that you have in mind, there's an ideal way to expose and develop the
    negative. You can't deviate from this much and still obtain the ever
    elusive "perfect" print.

    So for critical prints, +/- half a stop, which is still a lot more latitude
    than color slide.
    brougham5, Jan 12, 2004
  17. Robert Whitehouse

    Dan Quinn Guest

    Have you ever worked with a pinhole camera equipped with a
    meniscus lens? Have you any source material on such an arrangment
    you would recommend? Dan
    Dan Quinn, Jan 12, 2004
  18. Robert Whitehouse

    Paul W. Ross Guest

    I have gauged my pinholes with what used to be called a "stylus
    microscope" that I happened to have.

    As to a nice way to make pinholes, I have followed the strategy in the
    old Focal Encyclopedia -- make a dimple, prick it with a fine needle
    (tapestry needles seem the best), and then sand the protrusion on a
    flat surface (glass) with 800 grit sandpaper (from local hardware
    store). Use use the sheet aluminum from "disposalble" pie plates.

    Mine comes out to f350. I was more concerned with reciprocity failure,
    as I'm out to the better part of a minute for some of the exposures.
    Paul W. Ross, Jan 12, 2004
  19. Hate to be the one to point this out, but it wouldn't be a pinhole camera
    anymore with a lens of *any* type.
    David Nebenzahl, Jan 12, 2004
  20. Robert Whitehouse

    jjs Guest

    That's just a conventional lens-camera with a small aperture.
    jjs, Jan 12, 2004
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