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Thread: Adjusting Phase One DF focussing screen

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    Adjusting Phase One DF focussing screen

    I have an interesting problem. Autofocus on my DF works very well and accurately, but manual focus does not. This is not generally much of an issue because much of my work is landscapes where I'm using f11 or thereabouts. But when using a TS lens or the 240 mm at full aperture, it becomes important.

    Without going into all the details, it's clear to me that the screen is not in the right plane and needs a slight upwards adjustment.

    Anybody know how this can be fixed - other than sending back to Phase?
    Bill CB

    www.billcaulfeild-browne.ca
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    Re: Adjusting Phase One DF focussing screen

    Hi Bill,

    Have you checked the focusing screen to see if it's seated properly? Are you using a mask for a crop sensor back? You can see the procedure for how to adjust/reseat/add a crop mask here: https://www.youtube.com/watch?v=R4JBCJcvV64

    Cheers,
    Chris
    Chris Valites
    Research, Marketing & Support, Capture Integration
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    Re: Adjusting Phase One DF focussing screen

    Hi Chris, thanks for responding. I'm using an IQ180 back and thus do not have a mask. But you have set me to wondering if the camera was originally adjusted with a mask - the extra thickness might be what is needed, though I doubt it would be enough.

    I'll experiment with a homemade cardboard mask - if it moves the screen in the right direction presumably it would just be a matter of shimming with the right thickness.

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    Re: Adjusting Phase One DF focussing screen

    Which side of focus does the screen seem to be on? When you use AF, I assume the screen image is out of focus, which way do you adjust the focus so the screen image is in focus? If you focus toward infinity, then your screen is too close and the missing mask, if it went below your focusing screen, is missing (if my mind is not as fatigued as it feels).

    But are you sure it is the focusing screen and not the back? If the back mount is off, it will also result in the same thing.

    Then the question is which is easier to adjust?

    BTW, a displaced mirror will also result in the same problem.

    Phase cannot send you a loaner while they look at your camera?

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    Re: Adjusting Phase One DF focussing screen

    Quote Originally Posted by Bill Caulfeild-Browne View Post
    I have an interesting problem. Autofocus on my DF works very well and accurately, but manual focus does not. This is not generally much of an issue because much of my work is landscapes where I'm using f11 or thereabouts. But when using a TS lens or the 240 mm at full aperture, it becomes important.

    Without going into all the details, it's clear to me that the screen is not in the right plane and needs a slight upwards adjustment.

    Anybody know how this can be fixed - other than sending back to Phase?

    Bill - how are you setting your diopter?


    Steve Hendrix
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    Steve Hendrix, Sales Manager, www.captureintegration.com (e-mail Me)
    Digital Cam: Phase One | Leaf | Leica | Sinar Authorized Reseller
    TechCam: Alpa | Cambo | Arca Swiss | Sinar Authorized Reseller

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    Re: Adjusting Phase One DF focussing screen

    Ok, let me see if I can answer all the helpful questions!

    The fact that autofocus is accurate implies the back is properly mounted.
    I've checked the diopter is correctly set.
    I've checked the screen is in properly, the right way up (it can only go in one way.)

    The autofocus does not work off the screen - it has a separate reflector attached to the mirror.

    All my lenses require me to focus them nearer than the infinity mark for the images to be sharp on my computer. But they then look blurred through the viewfinder.

    The autofocus, when focussed on a distant object (5 miles!) stops the lens short of the infinity mark. Images look sharp on the computer but blurred in the viewfinder.

    When examining images on my computer screen (a) auto focussed are sharp (b) manual focus are not sharp and (c) manual focus with a slight twist in front of the infinity mark are sharp.

    (a) and(c) do not look sharp in the viewfinder - (b) does, but not on the computer screen.

    I therefore conclude that it's the focussing screen that is in the wrong plane. However, it might be the mirror that's wrong though there appears to be no way to adjust it. The stop that it rests against appears to be fixed and not adjustable.

    I intend to shim the focus screen to see if that helps, though I had hoped there was an adjustment screw or something that would change the plane of the screen.

    I'll report after the weekend!
    Bill CB

    www.billcaulfeild-browne.ca
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