A&P Extension tubes & magnification

Discussion in 'Lifestyle' started by mobbarley, Apr 26, 2006.

  1. mobbarley

    mobbarley Active Member

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    Im interested in extension tubes for my ef 100 2.8 macro lens. Canons website says this:
    Code:
    Magnification with Extension Tube EF 12:   1.19x - 0.12x
    Magnification with Extension Tube EF 25:   1.39x - 0.26x
    
    Does this mean that with a 12mm tube I can expect to see a 119% increase in magnification at one end of the focus range and an 12% at the other end????

    :dunno:
     
  2. eof

    eof New Member

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    :nono:

    It isn't true magnification...extension tubes just allow you to focus closer. So your lens is closer to the object. Magnification insinuates that from the same distance things appear closer and this is not the case. I have a 50mm lens with a 12mm tube and I don't think I would want anything closer...the 25mm with a 50mm lens would be overkill for my use. I would like to get a magnification filter however...
     
  3. mobbarley

    mobbarley Active Member

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    Really? My -probably incorrect- deduction is that for an extension tube to work the light has to be divirging when it hits the sensor. Adding a tube in will allow the light to divirge further providing magnification in a very similar fashion to how a 1.6 crop has more magnification over a FF.?

    Am I wrong?
     
  4. mobbarley

    mobbarley Active Member

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    okay I found this:
    Additional Magnification = (Extension Tube Length)/(Lens Focal Length)

    Another interesting note is that the 12mm will give me enough clearence to fit my teleconverter on, so I should be getting some fairly extreme magnification with that combo :hsd:
     
  5. eof

    eof New Member

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    hmm...I have tried a 12mm + 2x teleconverter and was not all that impressed. It worked better without the 2x.
     
  6. mobbarley

    mobbarley Active Member

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