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Thread: Tech Camera Focus Question

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    Tech Camera Focus Question

    Since looking around the forum, it appears that there are many technical camera users here. Interesting cameras to say the least!

    At the risk of asking a dumb question (and I have looked around but didn't find the answer elsewhere), but how do these cameras focus?

    The camera bodies appear rigid, the lenses look like traditional lenses in shutters....I just can't figure out where the focus mechanism is!

    What am I missing?

    -seeking enlightenment...

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    Re: Tech Camera Focus Question

    At least in the Arca Rm3di that I have it moves the lens back and forth using a helical focusing ring / mount. The lens is mounted (fixed) on a circular (cylindrical) metal mount open in the back obviously and small threads on the outside. You screw on the lens onto the mount (1/4 turn or less) on the camera and turn the focus ring on the camera body back and forth to achieve focus. On the Arca the thread is quite fine so small changes in focus are easy to achieve. Unless you want to focus very close (at least with wide angles and normal lenses) it does not take much movement of the lens back and forth to achieve focus.

    On the Alpa and Cambo I believe the lens has the focusing mechanism integrated in the back from the factory with an indexed focusing ring and that is mounted on a more typical flat lens board which is then mounted on the camera. So each lens has to have its own focusing mechanism where as on the Arca the focusing is on the body only and each lens is just fixed on the threaded mounts.

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    Re: Tech Camera Focus Question

    Much appreciate your solving my mystery!
    Thanks-

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    Re: Tech Camera Focus Question

    Quote Originally Posted by Ken_R View Post
    At least in the Arca Rm3di that I have it moves the lens back and forth using a helical focusing ring / mount. The lens is mounted (fixed) on a circular (cylindrical) metal mount open in the back obviously and small threads on the outside. You screw on the lens onto the mount (1/4 turn or less) on the camera and turn the focus ring on the camera body back and forth to achieve focus. On the Arca the thread is quite fine so small changes in focus are easy to achieve. Unless you want to focus very close (at least with wide angles and normal lenses) it does not take much movement of the lens back and forth to achieve focus.

    On the Alpa and Cambo I believe the lens has the focusing mechanism integrated in the back from the factory with an indexed focusing ring and that is mounted on a more typical flat lens board which is then mounted on the camera. So each lens has to have its own focusing mechanism where as on the Arca the focusing is on the body only and each lens is just fixed on the threaded mounts.
    In addition, you rotate Arca helical focusing ring based on distance chart provided by Arca. You need some adjustments which depends on the digital back you are using. For an example, if Arca's chart says 1.0 for a given lens and certain distance (to nearest focus point), then you may have to dial 3.0, if your focus factor is 2. This focus factor you need find by your own testing only for your MFDB, lens and aperture combination.

    Subrata

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    Re: Tech Camera Focus Question

    I shoot with an older back, tethered only. Presumably with the newer backs, there is a live-view option with the display on the back that can be used for live focus?

    At any rate, I suspect there might be a tech camera in my future, I've been inspired by some of the work I've seen posted here

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    Re: Tech Camera Focus Question

    In some cases, you focus on ground glass. Then, in addition, with use of sliding backs, which also allow stitching, you slide the back over and take your shot. Exact alignment between the GG and the sensor plane is critical, so some makers (Alpa) are not in favor of this; others use with good success.

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    Workshop Member lance_schad's Avatar
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    Re: Tech Camera Focus Question

    Quote Originally Posted by FoodShooter View Post
    Since looking around the forum, it appears that there are many technical camera users here. Interesting cameras to say the least!

    At the risk of asking a dumb question (and I have looked around but didn't find the answer elsewhere), but how do these cameras focus?

    The camera bodies appear rigid, the lenses look like traditional lenses in shutters....I just can't figure out where the focus mechanism is!

    What am I missing?

    -seeking enlightenment...
    The pancake type technical cameras focus via a Helical Focus Mount. The Cambo and Alpa use a similar mechanism that has a specific mount for each lens, and the Arca-Swiss uses a helical mount that is mounted to its lens panel and is shared by all of the lens. With both types focus mechanisms you figure out the distance via best guess, laser distance meter or Arca-Swiss Cloud Module and dial the focus in via distance calculated. If you are using an IQ1/2 or Credo digital back you also have the capability of using Live View on the digital back itself.


    Take a look at this video demonstrating Live View with a Phase One Back on a Tech Camera.

    Here is also another video specifically on focusing the Arca-Swiss R-Series with an older back that does not have Live View.

    For more information on tech cameras in general we have a whole section of our website dedicated to Arca-Swiss and Cambo Technical Camera Solutions including Focus Equivalency and Image Circle tools, here.

    Lance
    LANCE SCHAD - Digital Transitions - Phase One,Mamiya | Leaf,Arca-Swiss,Cambo, Profoto
    direct/cell:610-496-5586 office:877-367-8537x224
    http://www.digitaltransitions.com email:[email protected]

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    Re: Tech Camera Focus Question

    Thanks for those links Lance. Very helpful in understanding how these cameras are designed for use.

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    Senior Member stephengilbert's Avatar
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    Re: Tech Camera Focus Question

    There are close up photos of ALPA lenses here: ALPA of Switzerland - Manufacturers of remarkable cameras - Schneider/ALPA Apo-Helvetar 5.6/28 mm XL, LB

    They show the helical mounts, and distance settings.

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    Re: Tech Camera Focus Question

    Thanks Stephen.
    Something about these cameras that is really intriguing. Evidently many others have given in to the call.

    Maybe it's the simplicity of the overall concept executed in a really sophisticated package. A pinhole camera on steroids.

    <just what I need...another camera! >

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    Senior Member kdphotography's Avatar
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    Re: Tech Camera Focus Question

    I'm still trying to figure out the auto-focus on my Cambo.

    Focusing and composing with the IQ180 makes using a technical camera pretty easy. I tried out Don Libby's Cambo ground-glass with the shiftable hood and loupe and tupperware cover for the MFDB---and have to say I like it. It provides yet another focusing option for the Cambo technical camera. Yeah, I bought it.

    https://captureintegration.com/produ...g-hood-bundle/

    https://captureintegration.com/produ...ndglass-frame/

    https://captureintegration.com/produ...-slw-adapters/

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    Re: Tech Camera Focus Question

    Hi guys, i was wondering on a cambo with p45+ back or hasselblad back tethered to a laptop, can one focus the cambo using live view on the laptop in C1? I plan on renting this setup this week and will post some results all the best, MM

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    Member weinlamm's Avatar
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    Re: Tech Camera Focus Question

    Yes; the P45+ should have Live view via C1.
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