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Thread: New Autofocus 4x5"

  1. #31

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    Jun 2019
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    Western Massachusetts, USA
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    Re: New Autofocus 4x5"

    Quote Originally Posted by Hugo Zhang View Post
    How easy to put a lens on the camera? Like other 45 Graflex SLR with a lens board?
    It would be cool if there were electric contacts on the lens board, somewhat like DX coding on 35mm canisters, for the camera to know what the focal length is and automatically adjust its AF accordingly

  2. #32

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    Sep 1998
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    Loganville , GA
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    Re: New Autofocus 4x5"

    Quote Originally Posted by Ethan View Post
    It would be cool if there were electric contacts on the lens board, somewhat like DX coding on 35mm canisters, for the camera to know what the focal length is and automatically adjust its AF accordingly
    But how would the lens board know what focal length and speed the lens to be mounted to it will be?

  3. #33

    Join Date
    Nov 2015
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    51

    Re: New Autofocus 4x5"

    Quote Originally Posted by Bob Salomon View Post
    But how would the lens board know what focal length and speed the lens to be mounted to it will be?
    You will of course provide the focal length when you calibrate the lens, and the F stop is set in the integrated semi spot light meter.

  4. #34

    Join Date
    Nov 2015
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    51

    Re: New Autofocus 4x5"

    Quote Originally Posted by Hugo Zhang View Post
    How easy to put a lens on the camera? Like other 45 Graflex SLR with a lens board?
    Really easy. It has a large thread mount. And a removable adapter for wide angle lenses (65-75.. and maybe 90 also) that sets the lens plane a bit lower.

  5. #35

    Join Date
    Nov 2015
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    51

    Re: New Autofocus 4x5"

    Quote Originally Posted by Ethan View Post
    It would be cool if there were electric contacts on the lens board, somewhat like DX coding on 35mm canisters, for the camera to know what the focal length is and automatically adjust its AF accordingly
    That would be cool, but not sure if its really worth the wiring issues. Though there are ways it could be made really simple. Basically a single resistor would do the trick, so that would only require two wires.

    But the main issue would be that it would add complication to the user, you would need to somehow now insert resistors into your lens board. And the whole idea has been to make the lens board system simple, so that anyone can get them easily and put together extended boards etc. Its completely open system. Also a thing i have been using & developing for multiple years.

    As we all know, that lens boards are pain in the ass in LF cameras. 3D printing has basically solved the issue, but i rather not expect people to own printers. Or want to use plastic boards.

    When you change the lens, you just select it from the lenses you have stored in the camera. I will make it so that when you start the camera it always shows clearly what lens has been selected, to avoid issues of having selected a different lens than you are actually using. Maybe like showing the current lens so that it fills the whole finder for 1-2sec when you start it.

    The finder is actually the coolest thing about this, i just cant show it properly yet as i destroyed my only test screen.

    The core of this system is the finder & the ability to calibrate basically unlimited amount of lenses. The autofocus came later.

  6. #36

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    Sep 1998
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    Re: New Autofocus 4x5"

    Quote Originally Posted by fist View Post
    You will of course provide the focal length when you calibrate the lens, and the F stop is set in the integrated semi spot light meter.
    I wasn’t questioning your procedure. I was stating why dedicated lens boards would not be wise.

  7. #37

    Join Date
    Nov 2015
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    51

    Re: New Autofocus 4x5"

    Quote Originally Posted by Ethan View Post
    Great! I can mount my 48" aero ektar to this camera! :P

    This is an awesome project, I look forward to more updates!
    Yes Well, im a large aperture lens geek. So i have to make this work with the big boys. Im really tempted in slapping a Compound #4 with a 165/2.7 Tessar onto this. I have not dared to test it yet.

    But all the usual suspects, like Xenotar 150/2.8 i think should work. Planar/Xenotar 135/3.5 would be quite ideal for this, its not even a big lens and the focal length would be quite optimal.

    I have already calibrated a 135/3.5 lens onto this, and the focusing is perfectly accurate wide open.

  8. #38

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    Nov 2015
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    51

    Re: New Autofocus 4x5"

    Quote Originally Posted by Bob Salomon View Post
    I wasn’t questioning your procedure. I was stating why dedicated lens boards would not be wise.
    Yes, sorry. I misread. And you are exactly correct, it would simply add complexity.

    You would have to add a resistor to the board. Different resistance values would indicate different boards, and that would be matched by the data stored in the camera. So all it would need, is for the camera to recognise individual boards, the data would be stored in the camera.

    There are of course other ways beside resistors, like magnets that could be used. But all in all, its just not worth the hassle.

  9. #39

    Join Date
    Dec 2014
    Location
    Iowa City, Iowa
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    Re: New Autofocus 4x5"

    Brilliant work, I look forward to seeing more.

  10. #40

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