Extension Tubes

Discussion in 'Photography Beginners' Forum' started by florenceinitaly, Jan 21, 2010.

  1. florenceinitaly

    florenceinitaly TPF Noob!

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    I've seen extension tubes mentioned as a good macro lens alternative in several photography books that I'm reading - after googling them they look like they would be a good accessory to have.

    My question is though, since there are no electrical connections in the extension tubes, how do you control focus and aperture? For focusing I guess manual focus would be fine, but I can't control aperture manually on my camera - how is this going to work?
     
  2. Overread

    Overread has a hat around here somewhere Staff Member Supporting Member

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    The very cheap tubes do not have the electrical contacts and so yes you are correct - that means you can't control the aperture. With canon camera lenses you can trick the blades to be shut all the time at a set aperture, but that is not only fiddly, but also means that you have to focus a shot at small apertures which means a very dark viewfinder image - even for manual focusing (since AF is not possible with such a setup and manual focusing is also preferable when shooting macro)

    The trick is to get some better tubes - the Kenko AF range of tubes do have the electrical contacts and thus will preserve your communication with the lens.
    Another alternative is to use a highquality diopter on the lens - such as a Raynox DCR 250 or Canon 500D (product name for canons diopter lens as well as a camera model) which will work in a similar way as the tubes, but with a glass element on the front of the lens. Image quality wise its not too dissimilar from using tubes to get to such magnifications (dispite common thinking tubes do cause some image degradation, but in most cases is far to minor to concern ones self about and other factors such as shutter speed, subject movement and handshake will have a far greater impact on the photos quality)
     
  3. Dao

    Dao No longer a newbie, moving up!

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    Some extension tube has electrical contacts.

    i.e. Promaster
     
  4. c.cloudwalker

    c.cloudwalker TPF Noob!

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    First of all, yes, you can control your aperture manually. Unless you have a P&S. Read your manual.

    Second, when it comes to macro work, I don't think manual focus and exposure is much of an hindrance but I don't do much macro so somebody else may very well correct me on that one.

    I use an extension tube for the very little macro work I do and I find it just fine but it is not serious photo work so it really doesn't matter.
     
  5. florenceinitaly

    florenceinitaly TPF Noob!

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    Doesn't it depend on what lens you have? Some have an aperture ring for manual control but some doesn't. I don't think mind does, so how can I still manually control aperture? =S
     
  6. Big Mike

    Big Mike I am Big, I am Mike Staff Member Supporting Member

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    You are correct, not all SLR lenses are capable of having the aperture adjusted manually. All Canon EF lenses for example, need to be connected to the camera for aperture control.
     
  7. florenceinitaly

    florenceinitaly TPF Noob!

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    So then if I don't have aperture ring, and i connect one of these extension tubes without electrical connections, what will my aperture be? wide open or small?
     
  8. Dao

    Dao No longer a newbie, moving up!

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    If your camera is the Canon EOS, it will be wide open. And I believe Nikon is the other way around (I could be wrong)
     
  9. florenceinitaly

    florenceinitaly TPF Noob!

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    how about a sony a500 lol
     
  10. Big Mike

    Big Mike I am Big, I am Mike Staff Member Supporting Member

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    Lenses default to wide open. When you look through the viewfinder of an SLR camera, you are looking into a mirror and out through the lens. If the lens was stopping down, the viewfinder would get darker and darker.
     
  11. Dao

    Dao No longer a newbie, moving up!

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    Maybe unmount the lens from the camera and look at the glasses. If you do not see any shutter blades, then the lens is wide open.
     
  12. c.cloudwalker

    c.cloudwalker TPF Noob!

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    My bad. Shows you how much I still have to learn about digital...:grumpy:
     

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