Adapting a leaf shutter lens to Minolta/Sony 35mm?

Discussion in 'Camera Building, Repairs & Modification' started by cny3123, Apr 24, 2011.

  1. cny3123

    cny3123 Member

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    Hey all, I was curious to know if anyone would know how to go about potentially adapting a leaf shutter lens, such as the Bronica lenses, or Mamiya leaf shutter lenses to work on a Minolta film body or Sony digital body (Alpha Mount)?

    I am very curious to do something of the sort because I would like the ability to use a flash synched at 1/500th of a second, opposed to a stop slower at 1/250th, or potentially even slower depending on the body.

    I know there are lens adapters for Mamiya 645 lenses, but will they work with the leaf shutter properly if you hook the flash up to the PC sync on the lens?

    I've asked around at Dyxum and FM as well, but haven't quite found out what I am looking for just yet.

    Thanks for any help/advice.
     
  2. Diapositivo

    Diapositivo Subscriber

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    I don't know about your specific question.

    Maybe you might want to research about slow-burning flash bulbs, they would allow you to use fast shutter times with your Minolta film body or Sony digital body (without need to resort to a leaf shutter). They might serve your purpose. Never tried them personally, I suppose you should do some experiments to see how synchronization works.

    By the same token, some flash-camera combination now offer "high-speed synch". The electronic flash fires a long flash (a burst of many small flashes that behave like a long flash) and allows you to use any shutter speed.

    I suspect, but am not sure, that this function is only dependent, really, on the flash and that the only "compatibility" that the camera must have is that it must not revert to the max synchronization time when the flash is ready to fire (modern cameras have a pin on the flash mount whereby the flash informs the camera that it is ready to fire, and the camera accordingly sets the max synchronization shutter time if a faster time is manually selected).

    So I suggest you try to have somebody give you a "high-speed" flash and do some test with high shutter speeds, and report back. :wink:

    You might have to put some tape on the small pins of the flash socket to prevent flash-camera communication.

    PS The high-speed flash might not work well as the camera should fire the flash when the first curtain begins its trip, not when the first curtain ends its trip.
     
  3. polyglot

    polyglot Member

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    Heh, I was pondering that tonight. I think what you'd need to do is the following functional chain:
    - camera in M mode, approx 1/15
    - button on adapter closes leaf shutter
    - press camera trigger
    - mirror goes up, focal plane shutter opens
    - PC sync from camera triggers leaf shutter
    - FP shutter closes
    - leaf shutter re-cocked manually

    The problem is the bit where you have to close the leaf shutter before opening the focal plane shutter. That means that if you want to use the camera's release button, you need two actions to fire, which is slow. Sort of like mirror pre-fire on an RZ.

    If you're good with electronics though you should be able to make the adapter trigger the camera. You'd need to make a little state machine to follow this sequence:
    - press release on adapter
    - adapter closes leaf shutter
    - adapter waits ~50ms
    - adapter fires camera through elec contacts
    - FP shutter opens
    - PC sync from camera triggers leaf shutter
    - PC sync from leaf shutter triggers flash
    - leaf shutter closes
    - FP shutter closes
    - lens is recocked

    It's a lot of stuffing about to get long, slow lenses that may not be sharp enough for smaller formats, especially wide open. You might find it's easier just to buy a bigger flash and use an ND.
     
  4. polyglot

    polyglot Member

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    ... and that ignores all the mechanical horribleness like focusing and operating the cocking levers. And your adapter will need power. Might actually be easiest to start with a sacrificial body for the mechanical bits and focusing.

    You'll probably need to know how to program a microcontroller and do the necessary interfacing electronics.
     
  5. cny3123

    cny3123 Member

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    Hm, I didn't think it would be this complex. For some reason the way I envisioned it working was:
    Camera body mirror and shutter down, open the leaf shutter to focus.
    Then after close leaf shutter, raise mirror/shutter on body. Trigger leaf shutter and soon after close the body shutter/flip mirror down.
    This I figured could all be done with manual settings on the camera body, and finding the appropriate leaf shutter lens that can be triggered and opened manually.

    The idea of a more powerful flash may be worth looking into instead though. I just figured this could potentially be a cheaper option, though it is starting to sound like more trouble than it may be worth.
     
  6. Bob-D659

    Bob-D659 Member

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    The Pentax 645 line has all the smarts for this built in to the body and leaf shutter lenses, and gets you nice medium format negs as well. :smile: The new D body might even support the leaf shutter lenses as well.
     
  7. Gerald C Koch

    Gerald C Koch Member

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    You may be disappointed with the final result should you every get such a cross to work. This is because the resolution of medium format lenses is less than that for 35 mm lenses.
     
  8. Dan Fromm

    Dan Fromm Member

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    Gerald, why do you believe that?

    Chris, its even worse than you think. MF SLRs that use lenses in shutter cock and fire the shutter through the body. I got curious and looked for adapters for putting lenses in shutter, e.g., for Bronica SQ or Hasselblad, on a 35 mm or digital SLR. As best as I can tell the adapters don't have the necessary linkages -- the target SLR doesn't either -- and are made for using the lenses with shutter open and manual stop down. What you want to do is physically possible but not easy.

    As has been pointed out, changing from viewing to shooting back to viewing is problematic too.

    Have you considered getting an MF leaf shutter SLR with a digital back? Not cheap, but these bonbons do all the work ...
     
  9. Diapositivo

    Diapositivo Subscriber

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    Maybe adopting a Large Format lens would work better. As far as I understand, LF lenses have no communication with the camera body. They have a shutter release and a flash synchro. So you could adopt a LF lens, keep the camera on T (or lock the flexible cable on B) and use the shutter of the lens.

    That supposes you use a full mechanical body (a Minolta SR mount such as one of the Srt series as an example). If you don't use a mechanical body, the B position or the T position might be draining battery energy and the practice is going to become expensive and frustrating soon.

    Fabrizio

    PS That would go for studio work only. You first compose with shutter open, then close lens shutter, then open SLR shutter, than take flash-synchro picture, then if necessary close the SLR shutter and recompose.
     
  10. Gerald C Koch

    Gerald C Koch Member

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    Just look at the resolution (lines/mm) for a normal lense from each format. MF lens are covering a much larger negative size so they don't need the resolution that a 35mm lens requires. It gets even worse because the modification will be using only a small portion of the image of the MF lens.
     
  11. Dan Fromm

    Dan Fromm Member

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    Jerry, would you please be more specific? Point me at tests including, please, tests of lenses for the Mamiya 7.
     
  12. John Koehrer

    John Koehrer Subscriber

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    I did this about 40 years ago with a cheap T mount bellows and a lens/leaf shutter stuck on the front. 135mm FuSchNikonagon w/x synch.
    IOW see reply #5. It's that simple.
     
  13. Dan Fromm

    Dan Fromm Member

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    Um, John, I've never done it. But I do have a Graflex SLR set up to attach to a 2x3 Cambo standard, a couple of view cameras, and a couple of press cameras. Slow working, as your bellows rig must have been.

    The poor OP, however, wrote about using a lens for a leaf shutter MF SLR, not a lens set up to be used on a press/technical/view camera. This is a little harder because those lenses are in shutters set up to be cocked and fired by linkages from the camera body. More pain. I've adapted a 60/5.6 Konica Hexanon ex-Koni-Omega to my 2x3 cameras. In its native shutter, with no cable release and with release at the rear, it is simply unusable on anything but a K-O. I solved the problem by putting the cells in another shutter.

    Cheers,

    Dan
     
  14. Gerald C Koch

    Gerald C Koch Member

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    Hi Dan,

    Maybe this will help. A normal lens for a 6x6 cm (120 format) camera is ~80mm while that for a 35mm camera is ~50mm. Find the lens resolution for a Hasselblad or Bronica 80mm lens and one for a 50mm Nikon lens. The lens manufacturers publish the lens test results. I would look at the resolution at 2 stops down from wide open for each lens. Usually there are three values for each aperture. These correspond to the resolutions for the negative at the center, off center and edge. The more lines/mm the better the resolution. If you look at several lenses in each group you will find that the resolution of a MF lens is less than that for a 35mm lens. Think about it, a MF negative requires less enlargement than a 35mm negative so less resolution (for the camera lens) is required to produce a comparable print. To produce a MF lens with the same resolution as a 35mm lens would make the price prohibitively high.

    Perhaps the following analogy will help. Several TLR cameras had kits so that 35mm film could also be used in them. You were essentailly using a MF lens for 35mm film. These kits never really caught on. Why? The resolution with the 35mm film was t0o poor.
     
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  15. Dan Fromm

    Dan Fromm Member

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    Gerry, thanks for the kind reply. I understand the theory you expounded, it is the conventional wisdom. Where's data that supports it? He who makes an assertion must deliver supporting data, not tell people who question him to find it themselves.

    Here's some: http://www.hevanet.com/cperez/MF_testing.html

    Short answer, some of the MF lenses Chris tested agree with the conventional wisdom, others refute it. Moral? Be careful with generalizations. There are also superb, by 35 mm still camera standards, and less than superb lenses for formats larger than 6x9.
     
  16. John Koehrer

    John Koehrer Subscriber

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    Hi Dan,
    The OP said "potentially" using a MF lens. Using a lens in a leaf shutter solves most of the problems regarding cocking linkages. And they're more compact too.