F stops

Discussion in 'Australia Photography' started by Don, Jul 13, 2003.

  1. Don

    Miro Guest

    Beg for your life. You may not adress Sir Murphy directly.
     
    Miro, Jul 14, 2003
    #21
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  2. DoF calcs are "normally" based on a print size of 10x8 inches.
     
    Russell Stewart, Jul 14, 2003
    #22
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  3. Don

    Danny Smith Guest

    Thanks Bruce, Miro, Russell.

    Three different answers, all of which sound plausible... This is why
    Usenet is interesting!

    Oh well, I think I'll persist with the old 'focus and take a wild stab
    at f-stop' trick, and squinting determinedly through the viewfinder
    with the DoF preview button down!

    Cheers,

    Danny
     
    Danny Smith, Jul 14, 2003
    #23
  4. Have a look here for some more info...

    http://www.dudak.baka.com/dofcalc.html
     
    Russell Stewart, Jul 14, 2003
    #24
  5. Don

    Miro Guest

    I really dont think the viewfinder has enormous relevance. You should be
    able to gauge your shot without any kind of viewfinder at all. Rangefinder
    cameras give you a proxy of the shot at best.

    After all, the distances and DOF are marked on some lenses and when such
    information is not provided you really have question what the target market
    for that camera or lens is.

    I think you are looking for visual confirmation where I would be tending to
    use pratical ideals. The thing about f-stop and DOF is that it never changes
    at a given focal length. Once you know the lens you only need to compose and
    crop.
     
    Miro, Jul 14, 2003
    #25
  6. Say what??
     
    Russell Stewart, Jul 14, 2003
    #26
  7. The thing about f-stop and DOF is that it never changes
    I think I see what you are meaning by that now....
    I am getting sleepy and needed to read it a few times :)
     
    Russell Stewart, Jul 14, 2003
    #27
  8. Don

    Miro Guest

    Because it is on the lense, where it belongs.

    Is that supposed to pass for progress. In most cases cameras have done away
    with photographers and replaced them with bipods.


    DOF implies anything but exact focus. 50mm f1.0 might be a different story
    wide open. However I still contend that the focus plane is sharpest within a
    DOF range.
     
    Miro, Jul 14, 2003
    #28
  9. Don

    Bruce Murphy Guest

    Indeed, and it was particularly funny that you still don't have any
    idea why depth-of-field preview and rangefinders don't go
    together. But never mind, you've been shown to be an idiot before and
    I daresay you'll be shown to be again. Probably later in this post.
    Your claim was that when DOF isn't marked on a lens, you have to
    question what the target market of a lens was.

    I pointed out several technical reasons why it isn't practical to put
    DOF markings on lenses, in particular autofocus and zoom lenses.

    You responded with "Is that supposed to pass for progress. In most
    cases cameras have done away with photographers and replaced them with
    bipods". Since we are talkinga bout autofocus and zoom lenses you are
    either 1) gibbering randomly (As usual) or 2) claiming that autofocus
    and zoom lenses have done away with photographers.

    Being far more charitable than you deserve, I assumed you were not
    gibbering randomly and have pointed out that AF and zooms have not
    caused the death of photography.

    You then tell me that that wasn't the claim you made, leaving me to
    conclude that I really was being too generous and that you were just
    randomly gibbering about nothing in particular. Again.

    Feel free to read above, where it's all laid out.
    Wow. So you know that a lens focussed off at some point, you can tell
    the exact distance, has a particular DOF just becuase you can remember
    precisely what that DOF is becuase it's lens X. And you can tell the
    exact distance of focus and work out the precise DOF in your head?

    Personally, I think you're full of it. Again.
    Interesting use of the word contrast. You should probably look up what
    it means, becuase there isn't any at the edge of a DOF range, it's a
    perfectly smooth tailing off.

    B>
     
    Bruce Murphy, Jul 14, 2003
    #29
  10. Don

    Miro Guest

    As I own both I fail to see the truth in that.
    Yeah .... you would. I dont think a lens without an f-ring, let alone DOF
    markings apply to people who do their work carefully. How that relates to
    zooms and AF is your guess.

    I own several AF lenses with DOF markings. I also have owned several Nikkor
    zooms AF with DOF markings. Reality Bruce ...... try it.



    You think that all the time. If I didnt get that from you I would acuse the
    poster of being an imposter. Somehow in aus.photo physics conforms to
    popular opinion.



    I have to admit one thing, I am at a loss to explain your grasp of technical
    detail in the total absense of common sense. Photography works becauase of
    how the eye works. Working at the micron level you will never come to terms
    with the practical nature of images.
     
    Miro, Jul 15, 2003
    #30
  11. Don

    Bruce Murphy Guest

    Very few lenses don't have a focus ring. I presume that's what you're
    referring to, but AF lenses tend to have awfully short focus throw
    that would make a full all-aperture DOF scale uselessly complex.
    Look again. A single guess at two of the apertures really don't
    constitute a DOF scale in general terms.
    Yes, That was certainly one cute feature of the manual focus push-pull
    zooms. You'll note that not only have these died out, but that none of
    the other ways of doing zooms permit such a scale.

    Of course, I realise that you've never used a zoom lens less than 20 years
    old and merely extrapolate wildly to form all your conclusions.
    I love the way you quietly snipped precisely what I was talking about
    so that it *appears* I'm responding to your claim of DOF properties
    being linked to a lens are false, whereas I actually didn't believe
    you could keep a mental scale of all possible DOF depths *and*
    precisely judge focus distance as well.

    After all, if you can't get anywhere in an argument, why not quietly
    rearrange the words until they form one you can.
    ANd ignoring the micron level, you're going to continue making the
    same ridiculous statements. There is no sharply defined boundary
    between within the 'in-focus' DOF range and out of it, which is why
    different people can accept differing levels of sharpness and OOF blur
    in a photograph.

    Doubtless you're about to pull out yet another of your imaginary majors
    that deals with the structure and capabilities of the eye?

    B>
     
    Bruce Murphy, Jul 15, 2003
    #31
  12. Don

    Miro Guest

    No that was f-stop ring.
     
    Miro, Jul 15, 2003
    #32
  13. Don

    Bruce Murphy Guest

    Here in the technical land of photography, we generally call that an
    'aperture ring'. Try to keep up.

    So if a camera system provides some other means of changing aperture
    than a ring on the lens itself, it couldn't possible be used for
    serious photography? That's a pretty exciting claim you're making.
    Certainly indicates that you haven't been using much in the way of new
    cameras for the last 20 years.

    Do you claim that only certain colours of cameras can be used for real
    photography as well?

    Didn't like dealing with the rest of the post, I see.

    B>
     
    Bruce Murphy, Jul 15, 2003
    #33
  14. Don

    Bruce Murphy Guest

    These would be the same "everyone else" that points out that they've
    already kilfiled you, so would I please stop quoting your gibberish?

    B>
     
    Bruce Murphy, Jul 15, 2003
    #34
  15. Don

    Bruce Murphy Guest

    Frankly, miro, I doubt you're in any danger of attracting the attention
    of the thought police.

    B>
     
    Bruce Murphy, Jul 15, 2003
    #35
  16. Don

    Miro Guest

    I doubt you would pass the Turing Test.
     
    Miro, Jul 15, 2003
    #36
  17. Don

    Miro Guest

    Reboot yourself and try again.
     
    Miro, Jul 15, 2003
    #37
  18. Don

    Lionel Guest

    Ah yes, the 'thought police'. Always a favourite strawman for the
    net.kook brigade.
     
    Lionel, Jul 15, 2003
    #38
  19. Don

    Lionel Guest

    I doubt that you could sit it, let alone pass it.
     
    Lionel, Jul 15, 2003
    #39
  20. Don

    Don Guest

    Jesus! did I really start all of this? Ken, thanks for the info, great
    shot of Barrington.

    regards

    Don
     
    Don, Jul 15, 2003
    #40
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