Kenko Extension Tube

Discussion in 'Accessories' started by Always, Aug 9, 2015.

  1. Always

    Always Mu-43 Rookie

    12
    Jul 6, 2014
    Hong Kong
    Arthur
    Hi there,
    I recently bought Kenko Extension Tube for my Olympus EM-10 and lenses. I tested it on my native lenses, 60mm macro, 75-300mm, 25mm, and 14-42 Kit, they all work well except my 12-40 Pro lens. I cannot focus using this lens in any focus range. This is my first interchangeable DC. Just wanted to understand and learn more about photo taking. I believe it is relating to the Pro lens' structure. Anyone know the reason please!

    Many thanks,
    AC
     
  2. mjgraaf

    mjgraaf Mu-43 Regular

    53
    Feb 9, 2014
    Netherlands
    Menno
    Can you manually focus? Btw, extension rings work best on fixed focal length lenses. Zoom lenses are difficult as the impact of the extension ring depends on the focal length.
     
  3. Always

    Always Mu-43 Rookie

    12
    Jul 6, 2014
    Hong Kong
    Arthur
    I tried with both auto and manual focus in all available focal length but no luck:(
     
  4. Ross the fiddler

    Ross the fiddler Mu-43 Hall of Famer

    You would have got a 16mm & 10mm tube. Have you tried just the 10mm tube? You should try & manually focus on a subject with the lens within, say 100-200mm from the front of the lens first & when you seem to get the clearer focus appearance (at 12mm & 40mm zoom) then move the lens closer & further from the subject & see if it will come into focus then. It doesn't matter at what focus adjustment end it is at, close or infinity, it should appear in focus from somewhere between (at a guess) 1mm & 10m as you move to & from the subject, but just as an example, if I tried the EX25 (4/3's 25mm length) extension tube with the (4/3's) 14-54 II lens it would only focus right at the front of the lens, so you need to work out how close (working distance) the 10mm or 16mm (or both) tubes will focus with that 12-40mm lens. I believe that lens has a close focussing distance already & you may only be able to use the 10mm extension perhaps.
     
    Last edited: Aug 9, 2015
  5. Always

    Always Mu-43 Rookie

    12
    Jul 6, 2014
    Hong Kong
    Arthur
    Thank you for Ross's advice, I did try with both combination, with 10mm or 16mm or both. None is working with my Pro lens. I have mentioned that I could use it with my Kit lens with 14-42mm focal length which is very similar to the Pro 12-40mm. Actually, I could see blur image when I put the Pro lens almost touch the surface of the object; still a very blur image only.
     
  6. Ross the fiddler

    Ross the fiddler Mu-43 Hall of Famer

    That sounds similar to the 4/3's 14-54 II lens as that cannot be used with the EX25 either, so just enjoy the capabilities of that lens by itself & just use the extension tubes with the other lenses. I haven't had great success yet with the 60mm macro lens & extension tubes & prefer to use the lens by itself.
     
  7. RAH

    RAH Mu-43 Veteran

    271
    Dec 1, 2013
    New Hampshire
    Rich
    I tried to use a Kenko extention tube (smallest in my set was 12mm) with a Samyang 8mm fisheye lens (in Canon mount) and was unable to achieve focus. The wider the lens, the smaller the tube you need to use. I am surprised that with a zoom lens it won't work at the higher focal lengths, but that seems to be the way it is.
     
  8. tkbslc

    tkbslc Mu-43 Hall of Famer

    MFD is measured from the sensor. With a 10mm tube, you should have about a 170mm MFD. But the mount is 20mm deep, the tube is 10mm and the 12-40 lens is about 130mm long at full zoom. You might be able to focus 10mm in front of the lens.