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Extreme macro with 60mm f/2.8 plus extension tubes?

Discussion in 'Accessories' started by jamespetts, Dec 16, 2013.

  1. jamespetts

    jamespetts Mu-43 Top Veteran

    803
    May 21, 2011
    London, England
    Has anyone tried combining the Olympus 60mm f/2.8 macro lens with extension tubes to create a greater than 1:1 macro ratio? If so, did this work well?
     
  2. Rudy

    Rudy Mu-43 Veteran

    449
    Jan 24, 2013
    Oakland, CA
    Extension tubes on modern lenses don't work all that well.
    This has to do with the use of floating elements which move as you change focus.
    These elements assume a certain distance to the focal plane which would no longer be correct when using extension tubes.
    More directly to the point of your question.
    I have both the 60mm and some extension tubes, but never used the two together.
    It does however "work" in that you can still focus and the image is more magnified.
    You would need fairly long tubes to make much of an impact though and my gut feeling is that you're better off with cropping since the image taken with the tubes is not properly corrected by the floating elements.
    Rudy
     
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  3. jamespetts

    jamespetts Mu-43 Top Veteran

    803
    May 21, 2011
    London, England
    Thank you - that is very helpful. Can you clarify what you mean when you write that the image is not "properly constructed"; does it lose sharpness or introduce distortions or vignetting or something?
     
  4. shizlefonizle

    shizlefonizle Mu-43 Veteran

    372
    Apr 21, 2012
    I have a set of Kenko extension tubes I use with my PL 45mm Macro from time to time. I think it works pretty well if you want more magnification; about 1.82 with 26mm (10mm + 16mm) added. DOF becomes extremely small, I was pushing diffraction limits when shooting insects. Lighting and focusing also becomes more difficult at this level, and hand held shooting is still possible but I would recommend a tripod.

    Take a look at this site of a member, he was pretty much the macro expert here IMO
    https://sites.google.com/site/tadejtrstenjak/blog/panasonicleica45mmf28macrowithaddons
     
  5. Rudy

    Rudy Mu-43 Veteran

    449
    Jan 24, 2013
    Oakland, CA
    sample pictures

    I looked at the link provided and to my eyes most of the magnification seemed empty, i.e. did not show any more detail.
    So here is a quick test I did with the O60 manually set to 1:1 with and without a 26mm extension tube at both f/2.8 and f/5.6.
    The target was intentionally tilted to show out of focus behavior.
    These are screen shots taken from raw files that I zoomed to 1:1 in Lightroom, so they are relatively small section crops viewed at 1:1.
    To me, it looks like the images without the extension tubes have the same amount of detail if not more than the ones with the tubes, but feel free to disagree.
    Rudy
     

    Attached Files:

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  6. Rudy

    Rudy Mu-43 Veteran

    449
    Jan 24, 2013
    Oakland, CA
    more controlled images

    I noticed that the ISO was set on auto and the light wasn't very good.
    So here is a set with flash exposures at ISO200.
    Rudy
     

    Attached Files:

  7. jamespetts

    jamespetts Mu-43 Top Veteran

    803
    May 21, 2011
    London, England
    Hmm - doesn't seem to be much loss of sharpness in the latest set of those pictures...
     
  8. Ross the fiddler

    Ross the fiddler Mu-43 Hall of Famer

    Since extension tubes allow for a closer focussing distance, the working distance obviously becomes less (when the lens is focussed at the 1:1 position) & lighting might be less effective is some instances. I have them & have tried them a few times. My feeling is that they don't really give a great advantage because of a narrow DoF (& increased diffraction when stopping down too much to increase the DoF) & more critical conditions in getting focus so cropping the 1:1 photo from the 60mm is probably going to be easier & better in the long run. Thankfully the ones I bought only cost me about AU$43 posted, so it wasn't an expensive trial exercise (Kenko might be $100 extra).
     
  9. Wasabi Bob

    Wasabi Bob Mu-43 Top Veteran

    I use the Leica / Panasonic 45 mm macro with the Kenko tubes and they work just fine. These also support all AF operation. Have not had any problems other than the extremely narrow DOF which is to be expected.
     
  10. LowriderS10

    LowriderS10 Monkey with a camera.

    May 19, 2013
    Canada
    There shouldn't be...extension tubes have no lens elements. ;)
     
  11. jamespetts

    jamespetts Mu-43 Top Veteran

    803
    May 21, 2011
    London, England
    Well, that is what I originally thought, but one of the posters here seemed to imply that extension tubes can somehow degrade the image quality.
     
  12. Rudy

    Rudy Mu-43 Veteran

    449
    Jan 24, 2013
    Oakland, CA
    Just because extension tubes don't have glass in them doesn't mean they won't have an effect on the image quality.
    The extension tube alters the distance to the image plane. The lens is corrected for a certain image plane which no longer will be where it is supposed to be.

    In the old days lenses were focused by moving them away from the focal plane, so using an extension ring was simply doing the same thing only more so.
    Even then, image quality degraded when this was overdone and going beyond 1:1 would be better accomplished by reversing the lens to get it back to it's preferred magnification ratio. (Lenses don't really know which direction the light is coming from...)

    Modern lenses don't work that way and the vast majority of lenses now have a back element that doesn't ever move. These are field correcting elements and are optimized to work at a particular distance from the focal plane.
    In addition there are groups within the lens that move when focus is changed while other elements remain stationary or even move in opposite direction.

    Another drawback of extension tubes is alignment which could tilt the focal plane. Not much of a problem for 3D work, but really a problem on a copy stand.
    Sloppy tubes also might wobble, so that's something to look out for when getting cheaply made ones.

    Rudy
     
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  13. jamespetts

    jamespetts Mu-43 Top Veteran

    803
    May 21, 2011
    London, England
    An interesting analysis - thank you!
     
  14. ThomD

    ThomD Mu-43 Veteran

    424
    Jun 1, 2013
    SF Bay Area
    While I don't know anything about the details of modern lens design, I do not agree with the broad statement that extension tubes don't work well with modern lenses. My experience has been good.

    I don't use my ext tubes with the 60mm macro, but I did put them together to test it. It works. The depth of field goes to almost nothing at f/8. The minimum focus distance moves out a bit, but the field of view changes from .65 inches to .44 inches (horizontal),
     
  15. Dave in Wales

    Dave in Wales Mu-43 All-Pro

    Nov 5, 2011
    West Wales
    No one has mentioned light loss when using extension tubes, the more tubes you use the more light you loose.

    Back in my days of using film, adding extension tubes on to a 50mm to give a magnification of 1:1, resuted in a light loss of two stops.

    There is no light loss however when using supplimentary close-up lenses on the front of the lens.
     
  16. chonbhoy

    chonbhoy Mu-43 Veteran

    430
    Apr 23, 2013
    Scottish Highlands
    I've got a question. With both extension tubes on the 60mm what would the working distance be at 1:1 ?
     
  17. Sammyboy

    Sammyboy m43 Pro

    Oct 26, 2010
    Steeler Country
    You don't need extension tubes on the 60mm macro to get to 1:1, the lens can do it on it' s own.
     
  18. chonbhoy

    chonbhoy Mu-43 Veteran

    430
    Apr 23, 2013
    Scottish Highlands
    I know, I own one but what i wondered is along with the extra magnification you would get with tubes a little bonus might be a longer working distance at 1:1 than without tubes.
     
  19. Rudy

    Rudy Mu-43 Veteran

    449
    Jan 24, 2013
    Oakland, CA
    I just tried it with a 10mm extension.
    The working distance seems to be pretty much the same with or without the extension for the same image magnification at 1:1.
    You do get slightly higher magnification than 1:1, but not really all that much.

    This is easily explained by the simplified lens formula 1/f = 1/a + 1/b, with f being the focal length a the distance of the lens to sensor distance and b the lens to object distance.
    a/b is the magnification, so for 1:1 -> a = b = 2f.
    For a simple 60mm lens this would be 120mm on each side.
    For complex lens systems the distances lens to sensor and lens to object are not measured from the same spot, so the distance from a to b would not be 240mm on the Oly60.
    However adding a extension tube making one side 130mm would force the other side to 111.4mm and increase the magnification to only 1.167.
    You would have to add a 60mm tube to get to 2:1 magnification with a being 180mm and b being 90mm.
    Rudy
     
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