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looking for slim extension ring for M43

Discussion in 'Adapted Lenses' started by gnarlydog australia, Aug 31, 2016.

  1. gnarlydog australia

    gnarlydog australia Mu-43 Top Veteran

    967
    Feb 23, 2015
    Brisbane, Australia
    Damiano Visocnik
    I have several adapted lenses (manual focus, no electronic contacts) that have the focusing helicoid stop at 1 meter (minimal focus distance).
    I wish to go closer with those lenses but the extension rings I have now are too fat (thick) with the shortest one being 10mm. That moves the lens too far away from the sensor and makes it suitable for very close-up focusing only.
    I wish to find something in the 5mm range.
    I am also happy to DOY something by gluing two bayonet plates (one male, one female) together, but can't find parts suitable to make that.
    Anybody has come across/fabricates a shorter than 10mm extension ring?
    Very keen to hear that.
    BTW, the lenses are not SLR ones (with plenty of flange distance) but Pentax-110 or C-mount ones where there is no room for a helicoid-adapter...
     
  2. SVQuant

    SVQuant Mu-43 Top Veteran

    842
    Sep 20, 2015
    SF Bay Area, California, USA
    Sameer
    The slimmest one I have seen is 7mm (part of this set). I imagine that with your skills and ingenuity, you could also slice a wide one (10 or 16mm?) at 2.5mm from either end and glue them together for what you need!
     
  3. gnarlydog australia

    gnarlydog australia Mu-43 Top Veteran

    967
    Feb 23, 2015
    Brisbane, Australia
    Damiano Visocnik
    thank you for the suggestion
    I have the same set (I think) but that 7mm is the extension to be put between base and top part (modular system).
    I tried to pull apart that unit and wanted to glue together just the flanges but there are springs on the top plate (female part bayonet) that are free floating and need a base to be screwed/secured in.
    I was hoping for an off-the-shelf slim version before I start to futz with loose springs and tiny bits.... always looking for the easy version first, if possible :)
     
  4. SVQuant

    SVQuant Mu-43 Top Veteran

    842
    Sep 20, 2015
    SF Bay Area, California, USA
    Sameer
    I don't actually own that (have a 10 and a 16mm from Neewer). I guess that 7mm is the same as the 10mm I have. Measuring the depth of the lens bayonet part, I see that my initial suggestion of slicing it will not work. I think you need a solid piece and maybe getting one 3D printed would be the way to go?
     
  5. gnarlydog australia

    gnarlydog australia Mu-43 Top Veteran

    967
    Feb 23, 2015
    Brisbane, Australia
    Damiano Visocnik
    if I could find 3D printing in metal? I tried the plastic adapters in 3D print and they simply don't cut it as they wear too fast...
     
  6. tkbslc

    tkbslc Mu-43 Hall of Famer

  7. gnarlydog australia

    gnarlydog australia Mu-43 Top Veteran

    967
    Feb 23, 2015
    Brisbane, Australia
    Damiano Visocnik
    well, that looks like the set of rings suggested earlier and that I own.
    By just using the base and top it is still thicker than what I would like, and measures approx. 10mm
    I could unscrew the top "silver" part but there are tiny springs that need to be seated in the black base to make the bayonet retain the lens snugly. There is also the locking pin...
    At this stage I am still open to ready-made extension rings thinner than 10mm, before I bust out my oxy-acetylene torch :boohoo:
     
  8. listers_nz

    listers_nz Mu-43 Veteran

    255
    Nov 22, 2013
    Christchurch, New Zealand
    Simon
  9. dwig

    dwig Mu-43 Top Veteran

    621
    Jun 26, 2010
    Key West FL
    +1

    The bulk of the m43 flanges makes getting a very thin extension tube impossible. You will be much more successful finding or making extension tubes for the smaller mounts. The 5mm C-CS mount adapter would work well. It would be a bit of work, but a thin Pentax 110 mount extension tube would be possible.

    With a lot of work it would be possible to build adapters that provided their own adjustable extension, but they would likely reduce the diameter of the recessed cup preventing some lenses from fitting.
     
  10. Giiba

    Giiba Something to someone somewhere

    273
    Aug 19, 2016
    Burnaby, BC
    I know Shapeways can print in metal... not sure about tolerances though.
     
  11. gnarlydog australia

    gnarlydog australia Mu-43 Top Veteran

    967
    Feb 23, 2015
    Brisbane, Australia
    Damiano Visocnik
    thank you for the suggestions
    I use my adapted Pentax-110 lenses glued to a modified M39 adapter, with a iris diaphragm housed inside, between lens and rear of adapter. I can not put a spacer there :frown:
    28282611955_cf73544d50_c. Pentax-110 70mm 12-blade aperture_4 by gnarlydog, on Flickr

    My other C-mount lens is also a modified Cosmicar 50mm f1.4, again glued to a C-mount adapter. I can not put a spacer (typical C-mount extension ring) there either :shakehead:
    27511811384_58ef439f6f_c. Detail of mounting_c by gnarlydog, on Flickr

    OK, it looks like I will have to fabricate a (impossible?) 5mm extension ring by removing the female interface plate of a simple extension tube and glue it to a thin C-mount adapter :hmmm:
     
  12. Rambling Sam

    Rambling Sam Mu-43 Regular

    68
    May 27, 2016
    Reading, Berkshire, UK
    Sam
    I suspect that whilst it 'might' be possible to fabricate a 5mm spacer, the odds are that the 5mm of metal might be too 'weak' and distort, and the electronic contacts, might get wrecked in the process.

    Have you considered the much less complicated option of using a 1 Diopter (or 1/2 Diopter) close-up lens filter instead? The loss of image quality is going to be really minimal, especially if also use a lens hood, as this will improve the image contrast and reduce flare. However, this will only work if you don't ALSO want the lens to focus on infinity, without removing the CU lens.

    From what I remember having once dismantled a m4/3 to 4/3 adaptor, the combined depth of the tensioners once a bayonet mount is fitted, is almost, or more than 5mm! That, leaves you very little 'meat' to play with on the rear of the adaptor.
     
  13. gnarlydog australia

    gnarlydog australia Mu-43 Top Veteran

    967
    Feb 23, 2015
    Brisbane, Australia
    Damiano Visocnik
    Thank you for your input. You are good and on the money, in my view.
    5mm would be pushing it but 6 is achievable.
    I had the female part of my existing M4/3 10mm extension ring apart this morning and if I removed just the mating plate and placed it on a C-mount adaptor where I could get 6mm spacer/ring. There would be some tinkering involved with positioning the retention leaf springs (for the bayonet) and securing them to the flange but the stumbling block for me was the lens retention spring (that locks when the lens is rotated in place): I could not think of a way to make it fit/adapt in 4mm space.
    Heck, I was close to starting drilling, shaving and gluing... then something else caught my attention as I deemed the whole thing as "too-hard-basket"

    Thank you for confirming my second (but less preferred) option: dioptre lens.
    The thing is,I will have to source one for each lens with different filter thread size... I am looking at 49mm and 46mm diameter mainly.
    I already use hoods on all my manual focus lenses as most old-school low-cost ones aren't that well coated and flaring is common.

    Cheers.
     
  14. eteless

    eteless Mu-43 All-Pro

    Jun 20, 2014
    Rather than gluing it to a thin m39 adapter glue it to a lens cap which has a hole drilled in the middle?
     
  15. gnarlydog australia

    gnarlydog australia Mu-43 Top Veteran

    967
    Feb 23, 2015
    Brisbane, Australia
    Damiano Visocnik
    not sure if I follow you: do you mean camera body cap? in that case the body cap will need to have a hole drilled where the "lens retention pin" clicks in...
    I think a C-mount adapter is thinner than a camera body cap.
    Or do you mean something totally different that obviously I don't understand?
     
  16. Rambling Sam

    Rambling Sam Mu-43 Regular

    68
    May 27, 2016
    Reading, Berkshire, UK
    Sam
    I'd suggest getting a 49mm to 46mm stepping ring, but check out your hoods first ... If the 49mm is a screw-in type, and the 46mm isn't a wider angle lens, you might be able to use the same hood. You might be also able to apply the strategy to your other lenses too. Again, check out the focal lengths issue as well. Another way might be to 'cobble up' a pivoting black-matted 'Flag' on a polarising filter ring, so the 'Flag' can be rotated and tilted to block light from the offending light source ... More tinkering around, but it sounds like this kind of thing is something you enjoy doing! ... Just watch it, as things like this sometimes end up with people acquiring mini lathes, milling machines or both!
     
  17. eteless

    eteless Mu-43 All-Pro

    Jun 20, 2014
    I think I'm misunderstanding something, if the 'adapter' has the correct thickness so that when the helicoid is fully retracted the lens is at infinity any thickness of extension ring is going to result in the lens not being able to hit infinity. Therefor the thickness of extension ring doesn't matter since if 5 or 10mm it still won't hit infinity, why does it have to be so narrow? Why not just use the 10mm?
     
  18. gnarlydog australia

    gnarlydog australia Mu-43 Top Veteran

    967
    Feb 23, 2015
    Brisbane, Australia
    Damiano Visocnik
    true: what's the fuss about 5mm versus 10mm? (well, she might have a different opinion, but that's inches ;))
    Let's say I can focus to min. 1 meter on my "stock" lens and when I put on the 10mm extension ring I suddenly can focus between only between 40cm and 10cm.
    Often is the stuff just closer to "native" minimal focus that I can not reach, let's say 60cm.
    And that's why I am so bent on this 5mm extension ring. :drama:
     
  19. gnarlydog australia

    gnarlydog australia Mu-43 Top Veteran

    967
    Feb 23, 2015
    Brisbane, Australia
    Damiano Visocnik
    Sam, more of ideas like these and I will be looking up for mini lathes and other totally "unnecessary" tinkering equipment.
    I like the rotating polarizing "flag" idea but then couldn't I just go for a long lens hood? I am thinking of 50mm and 70mm lenses where long hoods will not fall into the view.
    Hold a second.... I just realized why possibly one of my super-ghetto refitted lenses gives me glowy results? the problem is adding a lens hood of 95mm diameter up front will make the thing look like paparazzi material! :eek:
     
  20. EdH

    EdH Mu-43 Top Veteran

    629
    Jul 14, 2014
    Devon, UK
    Ed
    Pentax did offer a close-up lens for the 70mm f2.8. I know it's not the solution you want, but it might be worth a try given that they don't seem expensive and there's no work involved.

    I found this one on ebay:

    Asahi Pentax Close up lens no.1 49mm Lovely condition
     
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