1. Reminder: Please use our affiliate links for holiday shopping!

12-40 with Kenko Extension Tubes.

Discussion in 'Native Lenses' started by Dave in Wales, Jan 11, 2014.

  1. Dave in Wales

    Dave in Wales Mu-43 All-Pro

    Nov 5, 2011
    West Wales
    https://www.youtube.com/watch?v=PHCq7mwMRm4

    In a word, well four actually, ‘don’t waste your money’…for this lens anyway.
    No doubt they work with longer focal length lenses, but I do not have one.

    They come in two lengths 10 & 16mm.

    With the lens set a 40mm a magnification of approx. 0.3 was achieved with a working distance (end of lens to subject, hood removed) of approx. 60mm.

    With the 10mm tube fitted a magnification of approx. 0.2 was achieved with a working distance (end of lens to subject, hood removed) of approx. 110mm.
    Coincidentally this was the same magnification/working distance of the lens on it's own, without the 10mm tube fitted.

    With the 10mm or the 16mm tube fitted a magnification of approx. 0.54/.58 was possible with a working distance (end of lens to subject, hood removed) of approx. ZERO, end of lens almost touching the subject.

    As I said……IMVHO Kenko Tubes are NOT for the 12-40, they have gone back to Amazon.

    If others decide to replicate my test and find errors, please don't shoot the messenger, I was just trying to establish whether it was worth keeping the tubes......for use with the 12-40.
     
  2. MajorMagee

    MajorMagee Mu-43 All-Pro

    Feb 24, 2011
    Dayton, OH
  3. orfeo

    orfeo Mu-43 Top Veteran

    673
    Sep 27, 2013
    FR
    Your zoom is too long in size. Try a reverse ring on it, though it may be too large. Or try a longer focal length.
     
  4. mister_roboto

    mister_roboto Mu-43 Top Veteran

    637
    Jun 14, 2011
    Seattle, WA, USA
    Dennis
    They work best with wider lenses.
     
  5. Mooring

    Mooring Mu-43 Regular

    27
    Dec 7, 2013
    Lee Mooring
    Someone tell me if I figured this correctly. The maximum magnification of the 12-40 is listed as .30. Using this to plug into the calculator it appears that with a 10mm extension magnification at the 12mm end would be 1.13 and a closest focusing distance of 48.2mm and with the 16mm extension tube it would be 1.63 with a closest focusing distance of 50.9. Or do we need to use the full frame equivalent numbers? In which case it would be .72X and 98.7mm or .97X and 96mm. These numbers don't sound too bad if I figured correctly. I have not done much macro photography in the past so I might be wrong.
     
  6. MajorMagee

    MajorMagee Mu-43 All-Pro

    Feb 24, 2011
    Dayton, OH
    The problem is the close focusing distance is measured from the sensor plane and it's just 50mm (2 inches), placing the subject theoretically somewhere inside the lens.
     
  7. humzai

    humzai Mu-43 Veteran

    410
    Apr 17, 2012
    What exactly is the problem are you unable to focus at a further distance? I don't know much about macro photography.
     
  8. Mooring

    Mooring Mu-43 Regular

    27
    Dec 7, 2013
    Lee Mooring
    So how do you figure magnification as you move away from the subject? If I understand these extension tubes correctly they can be combined for much greater magnification, in this case a 26m tube, which should allow one to pull back from the subject and still obtain significant magnification. I'm just learning here so don't mind correcting me if I'm wrong.
     
  9. Mooring

    Mooring Mu-43 Regular

    27
    Dec 7, 2013
    Lee Mooring
    Or does the length of a zoom lens negate this ability. I know primes tend to be a good bit shorter .
     
  10. Dave in Wales

    Dave in Wales Mu-43 All-Pro

    Nov 5, 2011
    West Wales
    I tried focusing at all distances, near and far, with single tubes and stacked.

    The only in focus results I achieved were as stated, near to touching the lens.

    I think the Major may have the answer.

     
  11. Mooring

    Mooring Mu-43 Regular

    27
    Dec 7, 2013
    Lee Mooring
    Sounds like they will only work with a wide angle prime that is physically much shorter. Learn something new every day. I had considered getting a pair and trying them out myself but but since I don't have a wide angle prime your experience will save me the time and effort.
     
  12. rklepper

    rklepper Mu-43 Top Veteran

    733
    Dec 19, 2012
    Iowa, USA
    Robert
    That is exactly the same thing that happened with me on my 25. The focus distance was just too close to be useful (probably my imagination, but the focus point almost seemed like it was inside the lens). The extension tubes worked okay on the 35-100, but never all that satisfying. I used them a few times and finally just ordered a proper macro lens.


     
    • Like Like x 1
  13. Yohan Pamudji

    Yohan Pamudji Mu-43 Veteran

    462
    Jun 21, 2012
    Mississippi, USA
    On the plus side the 12-40mm focuses so closely that it is a competent pseudo-macro lens even without extension tubes.
     
  14. dhazeghi

    dhazeghi Mu-43 Hall of Famer

    Aug 6, 2010
    San Jose, CA
    Dara
    This exactly. It's great for close-ups (flowers, plants etc.). The only place where it falls down is for true macros like those of small bugs. But for those I'd want more working distance and manual focus with a long throw, so a legacy 90 or 100 macro is basically a necessity either way.
     
  15. fredlong

    fredlong Just this guy...

    Apr 18, 2011
    Massachusetts USA
    Fred
    Adding extension tube requires you to move closer to the subject.

    With a simple lens the focal length is the distance from the lens to the sensor that focuses at infinity. As you move the lens further from the sensor you focus closer. At twice the focal length you will be at 1:1. This all works fine with a simple lens. You can keep extending it and getting closer to your subject

    With many modern lenses, especially zooms, the center of the complex lens may not be in the lens. With retrofocal wide angle lenses the center is moved deeper into the lens or camera body. With telephoto designs the center of the lens is somewhere out in front of the lens. Telephotos work great with extension tubes. You just need more extension as the focal length goes up.

    Zooms are a whole different animal. Telephoto zooms often work ok with extension tubes. Wide and wide to normal zooms, not so much. A high quality achromatic diopter is a good choice for for a wide zoom. Something like the Marumi +3 would probably be a good match for the 12-40.

    Fred
     
  16. chonbhoy

    chonbhoy Mu-43 Veteran

    430
    Apr 23, 2013
    Scottish Highlands
    I've asked in a seep rate thread about how good the Marumi 200 (+5) would be on the 12-40. If it's magnification is 0.6 natively what will it be with the Marumi 200?


    Sent from my iPhone using Tapatalk
     
  17. CPWarner

    CPWarner Mu-43 Veteran

    244
    Dec 24, 2010
    Cliff
    The Kenko extension tubes work fine with my 60mm macro. I have not tried them on anything else yet.
     
  18. MizOre

    MizOre Mu-43 Veteran

    201
    Dec 26, 2011
    Kenko tubes with a 100-300mm lens on a GF1. I just did some brief trials to see how they worked. This was both tubes (26 mm extension) at 100 mm. Detail of a paper mache Nicaraguan pageant mask.

    [​IMG]