Will the Nikon D80 or D200 do this?

Discussion in 'Nikon' started by E. E. Herbert, Sep 26, 2006.

  1. E. E. Herbert

    Bill Funk Guest

    The f/number is really easy; it's just a ratio of the lens focal
    length to the aperture opening.
    For example, let's use a 50mm lens. If the aperture is 25mm, the
    f/number is 2, because the ratio of the focal length to the aperture
    is 1:2. With the same lens, an aperture of 12.5mm would be f/4,
    because the ratio of the focal length to the apertire is 1:4.
    Why the odd numbers then? ASAAR covered the math, but the reason is
    because we are dealing with the area of a circle (the ideal aperture
    opening is a circle), thus the need to use square roots.
    The end result, though, is simple. Each established f/number is 1/2 or
    twice (depending on whether you're going *up* or *down* the f/number
    scale) the exposure of the preceding one. Thus, for example, f/4 will
    let twice the light through that f/5.6 does, and f/2.8 will let in
    twice as much light as f/4 will.
    It can be confusing, because a larger f/number means a smaller
    aperture.
     
    Bill Funk, Nov 30, 2006
    #21
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  2. And for simplicity, each full stop is 1.4 (square root of 2) times the
    previous full stop.

    f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22, f/32

    These full stops should really be memorized. Makes manual exposure much
    easier.
     
    Thomas T. Veldhouse, Nov 30, 2006
    #22
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  3. E. E. Herbert

    Bill Funk Guest

    Simplicity?
    How many people can do that math "simply"?
    I sure can't.
    Agreed, wholeheartedly!
     
    Bill Funk, Nov 30, 2006
    #23
  4. You don't find it simple to multiply by 1.4? I didn't say to do it in your
    head. In fact, that is why I said that one should memorize the whole stops.
     
    Thomas T. Veldhouse, Nov 30, 2006
    #24
  5. E. E. Herbert

    Cynicor Guest

    If you're American, just do exposure in two touchdown increments.
     
    Cynicor, Nov 30, 2006
    #25
  6. E. E. Herbert

    Bill Funk Guest

    No, actually, I don't. I'm math challenged. :-(
    I carry a PDA with me with the calculator on speed-button.
     
    Bill Funk, Nov 30, 2006
    #26
  7. E. E. Herbert

    ASAAR Guest

    Nah. Before multiplying by 1.4 most Americans would just punt.
     
    ASAAR, Nov 30, 2006
    #27
  8. E. E. Herbert

    ASAAR Guest

    Bill didn't make that f/8 comment. I did. You can figure it out
    by counting the number of ">" characters at the beginning of each
    quoted line. It's a pun, sort of, with f/8 falling halfway between
    f/2.8 and f/22. Have you heard of the Golden Mean, or learned the
    difference beteen "average" and "mean" in high school math classes?
    You don't have to even know the actual definition of "mean" to get
    it, you only need a slight familiarity with the term. And btw, my
    name is Bill too, so you actually got it right!
     
    ASAAR, Nov 30, 2006
    #28
  9. I am curious. A D200 seems like a rather large purchase for somebody that
    doesn't understand apeture and f/stop. I am glad to see you have an
    interested in learning it though and I am sure the D200 won't limit your
    progress. I just picked up mine last week (moving from a D70) and absolutely
    love the camera myself.
     
    Thomas T. Veldhouse, Dec 1, 2006
    #29
  10. f eight = "fate"?
     
    Thomas T. Veldhouse, Dec 1, 2006
    #30
  11. E. E. Herbert

    VX Guest

    Actually things haven't really changed, its just that they developed
    electronic cameras, so that opened up a lot of options that can be confusing
    if you didn't follow the gradual changes of camera design as they occurred.
    For example you say there are more f-stops, but there aren't. The range you
    saw on a manual focus camera a couple of decades or so ago would have been
    something like f2.8, f4, f5.6, f8, f11, f16, maybe f22. f8 lets in twice as
    much light as f11, and so on throughout the range. But an electronic camera
    such as a digital SLR can display the in-between aperture values also. These
    were there all along in between the marked positions on the aperture ring of
    the lens you held long ago, but they weren't indicated because that would
    have been too complex and confusing to put on a small aperture ring, and
    unnecessary anyway. But now since the aperture display can be on an LCD there
    is no reason why it cannot display the in-between settings.

    If you want to try a photographic tool that could really help you understand
    these exposure settings in an obvious and accessible way, I would recommend
    finding an old Weston Master 5 exposure meter. It should be the 5 or later
    since the earlier ones did not use ASA/ISO values and would confuse things. I
    have used one many times to see graphically where a particular aperture
    number fell into the whole range when comparing maximum f-stops, etc. it is
    also very useful for learning about exposure in a number of other ways. Now
    that I say that, I remember I lost mine a while ago so I will now go about
    getting another one. These are great learning tools. Basically an analog
    exposure meter that shows ALL the aperture numbers including fractions of an
    f-stop on one rotating ring makes it all clear. The Weston Master 5 is the
    one I'd suggest.
     
    VX, Dec 7, 2006
    #31
  12. E. E. Herbert

    VX Guest

    They can be. If you know anywhere that sells used or "classic" equipment,
    that would be the place to look for a used one. KEH in Atlanta (they have a
    web site) is generally recommended for ordering used camera gear by mail
    order. Although I think I saw that they were strill making these not so long
    ago! A web search might be a good way of researching where to find one of
    these. Or Ebay:

    http://search.ebay.com/weston-master-invercone_W0QQfnuZ1

    -but do bear in mind that these are generally quite old and so try to ensure
    you are buying one that is working.
     
    VX, Dec 7, 2006
    #32
  13. E. E. Herbert

    VX Guest

    In fact on this Ebay entry this photograph actually shows you most of what
    you need to know- all the apertures are visible and the whole stops (the
    values that are half or double the light of the next whole stop along) are
    highlighted in black. I'm going to print this image out and keep it, it will
    be useful to me too....

    http://imagehost.vendio.com/bin/viewimage.x/00000000/vanhook/west3.JPG?vvid=30
    691004&sp=1

    or look for the last pic here:

    http://cgi.ebay.com/Weston-Master-V-mod-748-w-case-invercone-etc-
    NR_W0QQitemZ150067068704QQihZ005QQcategoryZ4702QQssPageNameZWDVWQQrdZ1QQcmdZVi
    ewItem

    or look at the pics on the Ebay page I quoted in my previous post:

    http://search.ebay.com/weston-master-invercone_W0QQfnuZ1

    The second entry, last picture, is the one. At least until that page changes.
     
    VX, Dec 7, 2006
    #33
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