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How to make aperture stepless?
  • stoneystoney
    Konica Hexanon AR 40mm 1.8 is not sharp at 1.8 but very good at 2.8. It jumps from 1.8 to 2.8.

    I wanna make it stepless with good damping on the aperture ring. Can anyone shed some light on this topic? Thanks.
  • 19 Replies sorted by
  • Vitaliy_KiselevVitaliy_Kiselev
    Stepless is mostly easy (disassembling rear of the lens to various degree and removing small ball).
    Damping is not so easy. May be try to put something to the inside in diaphragm ring? Never done that.
  • stoneystoney
    Yeap yeap. That's the hard part. I don't wanna pay $500 to customize $45 lens.
  • Vitaliy_KiselevVitaliy_Kiselev
    >to customize $45 lens

    In this case get screwdriver and start making conversions.
  • stoneystoney
    Hmmm... drilling a tiny hole through aperture ring... a hole w/ thread... then a tiny screw w/ soft end might do it. But I need a machinist.
  • Vitaliy_KiselevVitaliy_Kiselev
    Sounds very complicated.
    May be try to glue thin PTFE inside ring?
  • stoneystoney
    Another idea. This could be a big hit... if someone can make it.

    Take out the tiny ball. Have a special metal piece w/ "half" ball end so that it can fit into the hole where the original ball was. The metal piece has built-in mechanical damping (e.g. rounded metal sheet) so that aperture ring has enough damping.
    ball.jpg
    640 x 478 - 91K
  • Vitaliy_KiselevVitaliy_Kiselev
    No one could make it. Just try to look at original ball size :-)
    And damping is working good only having large surface.
  • stoneystoney
    See the design pic.

    I don't wanna apply grease on aperture ring. Without a ball, it's pretty loose... the grease will leak.
  • Vitaliy_KiselevVitaliy_Kiselev
    >I don't wanna apply grease on aperture ring.

    This is good decision.
    But I offered to glue thin PTFE sheet (or 2-3, according to your lens) inside aperture ring.
    To make good dumping all you need is good friction, but not one that will stuck sometimes.
  • johnnymjohnnym
    The Helios 44m i have has stepless aperture. I paid 15$ for it, and it's quite sharp.
  • andresandres
    Maybe remaining the ball and sealing the holes on the inside of the bayonet for having a constant pressure. This is a interresting topic. the cinemod of lenses is really expensive. This mod and a set of half inch rails zip ties and we are set.
    http://cgi.ebay.de/Half-Inch-Rails-Zip-Tie-Follow-Focus-Lens-Gears-gear-/290548711228?pt=Filmnachbearbeitung&hash=item43a60d7f3c
  • andresandres
    Declicking Canon FD lenses :
    http://jag35.com/new/blog/removing-aperture-click-out-of-fd-lenses/

    Declicking leica: follow this steps just until you get to the ball. Remove it and reasemble.
    http://leitax.com/conversion/leica/elmarit-28-r-cam/index.html
  • jard667jard667
    Which grease he used for FD, or what would you recommend?
  • andresandres
    I would like to know the same thing.
    The leitax guy uses silicone grease, he also sells it.
    http://leitax.com/
    The problem with my leicas is that it needs damping.
  • DouglasHornDouglasHorn
    As a low-tech approach to aperture pulls on my FD lenses, I use the adapter's "Lock-Open" mechanism. Switching this from Lock to Open disengages the aperture, sending it wide open. So, if you set the lens's aperture ring to the smallest aperture you want and then open up the Lock-Open ring on the adapter, you can create two different apertures for the pull and reproduce it pretty well. (It's more consistent if you're going from a wider aperture to a smaller one, but you can make either work with practice.)

    Not ideal, but not bad in a pinch.
  • jard667jard667
    Main FD problem is imho in spring around the aperture. Around f16-22 is the spring tension very high.
    Is that spring really necessary for aperture itself, or is it only used to transfer force between body and aperture?
  • stoneystoney
    I guess stepless aperture is not that important. Also kinda risky mod.
  • neokooneokoo

    What about electronically controlled video lenses, like the micro 4/3 ones from Panasonic? AFAIK they are mechanically stepless, but cameras usually allow only 1, 1/2 or 1/3 stop adjustments. Making the adjustments in .1 or smaller stop fractions is a matter of software setting, is it not?

    Would such adjustment be possible to implement in hacked firmware, or would it be necessary to hack the lens firmware as well?

  • fosterchenfosterchen

    I know this is a different lens mod, but you maybe can use the same idea for a cheap dampening solution: Works really well for me!

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