Help with understanding macro. please!

Discussion in 'Photography Beginners' Forum' started by Fishboy, Feb 18, 2009.

  1. Fishboy

    Fishboy TPF Noob!

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    Looking at the specs for macro lenses "minimum focus distance is given, now, is this the closest you can get to the subject and still focus, or no further than the given distance away from the subject to be able to focus?

    Sorry if this is a daft question, an explanation would be a great help:blushing:


    Cheers,


    Fishboy
     
  2. TUX424

    TUX424 TPF Noob!

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    [ame="http://www.youtube.com/watch?v=GjEFVxMi6HY&feature=channel_page"]I hope this helps[/ame]
     
  3. Fishboy

    Fishboy TPF Noob!

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    Thanks, was interesting............but didn't answer the question?
     
  4. AUZambo

    AUZambo TPF Noob!

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    I'm 99% sure it's the closest you can get to the subject and still be able to focus. I've never used a macro lens, but I always assumed you could still focus to infinity if you wanted.

    This makes me wonder, would a 50mm macro lens be just as good as a 50mm non-macro at portraits??
     
  5. rpwiz

    rpwiz TPF Noob!

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    The minimum focusing distance is the minimum distance u have to be from the subject for the focus to work. Basically u have focus from the minimum to infinity. Macro lens have better magnifaction ratios then non macro lens. You'll need to read up on that i can't easily explain it.
     
  6. kundalini

    kundalini Been spending a lot of time on here!

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    Every lens has a minimum focusing distance. It is the minimum distance from your subject where the lens can maintain focus. I'm not 100% on this, but I believe the distance is measured to the sensor, not the front element.

    I took this photo for Fight Club this past week and it is ~1:1 ratio and I was ~1' (0.3m) away from the subject.


    EDIT: photo taken with Nikkor 105mm f/2.8 VR. At macro ratio of 1:1, max aperture is f/4.8 (and stinking razor thin focal plane.)
     
    Last edited: Feb 18, 2009
  7. rpwiz

    rpwiz TPF Noob!

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    Thats right Kundalini they Do measue from the sensor to the subject like i said early i think its more the magnifaction ratio thats important in macro not the focusing distance.
     
  8. EhJsNe

    EhJsNe TPF Noob!

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    Ive got a 25-105mm f.3.5 macro lens (well, it has a macro ability...) and it can focus from a couple inches away. Its also a pretty darn sharp lens, not bad for a $30

    So Id assume its the distance from the front element, and even if it is from the sensor, there is ones with enough magnification, you could be a couple feet (like 1-3) and still have a frame full of the subject.
     
  9. Overread

    Overread has a hat around here somewhere Staff Member Supporting Member

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    I don't know about the minimum focus distance - but each macro lens has a "working distance" which is the distance from teh subject to the sensor of the camera when the lens is a its closest focusing point (also its maximum magnification).
    Now first off all lenses have this distance, but its mostly not a concern except in macro where you are very close (cms) to subjects like insects which can be spooked and fly off if you get too close.
    Generally speaking longer focal length macro lenses are better since working distance is proportional to focal length (the longer the focal length the longer the working distance). And generall its recomended that a lens have 90mm or more focal length if you intend to work with insects. (if not then you can go as low as you like though the 50mm options are generally a bit lacking in build quality - some are also not even true macro lenses - there are of course some exceptions to this general rule
     
  10. Overread

    Overread has a hat around here somewhere Staff Member Supporting Member

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    This is very dependant on the insect, the focal length and also what magnification you are working with.
    Something like a butterfly will fill the frame at around half true macro magnifications - 1:2 magnification.Whilst a fly will need the full 1:1 magnification of a macro lens to full the frame.
    If your after a flea then you need even more magnifcation (and then things get tricky).
    One can focus to 1:1 on a butterfly, but you won't get the whole bug in the shot - only a portion of the insect because its so big (in macro terms)
     
  11. Chairman7w

    Chairman7w TPF Noob!

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    Good thread, let me ask a noob question here about Macro: How in the world do you get those REAL close pics. I've seen some amazing shots of insects (spider, ladybug, etc) that are incredible.

    I have a Tamron 90mm macro lens and I can't get nearly that close (to fill the frame with an insect). Am I missing something here? (shooting with a Canon EOS Rebel XS)
     
  12. kundalini

    kundalini Been spending a lot of time on here!

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    I'm just beginning in the macro world, but a suggestion I read from someone who is very good mentioned to frame for cropping. I've also found that my 1.7x teleconverter allows me to be further away and still get closer. Otherwise, I guess find a dead specimen and compose as you wish.
     

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