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Thread: Speed Graphic inaccurate focus

  1. #1

    Speed Graphic inaccurate focus

    I got a Speed Graphic a while back and have been noticing that all of my shots are soft where I focused and sharp about 1 inch front of where I focused.

    When I got the camera, it had the OEM fresnel and ground glass. I've been doing tests with pack film and with or without the fresnel, And the problem is the same with all of my shots.

    What's going on? This is frustrating.

  2. #2

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    Re: Speed Graphic inaccurate focus

    Is the stock Fresnel in front (lens side) of the GG, with the grooved side towards lens???

    Steve K

  3. #3
    Jim Jones's Avatar
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    Re: Speed Graphic inaccurate focus

    If the Fresnel is on the back of the ground glass, its presence or absence won't affect focus. I believe Speed Graphics that were factory fitted for a Fresnel were milled down so a factory Fresnel could be placed in front of the ground glass for correct focus. This has the advantage of protecting the somewhat delicate Fresnel. Unfortunately, it introduces the possibility of a focusing error if the Fresnel is removed, or a Fresnel of different thickness is used. Someone with greater expertise should provide more authoritative information soon.

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    Re: Speed Graphic inaccurate focus

    Also (for anyone who posts a SG question here), please research and state exactly which model they are inquiring about, because there are different configurations for different series cameras, and things like this, lensboards, backs etc are different...

    Post a pix if you are not sure...

    Good Luck!!!

    Steve K

  5. #5

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    Re: Speed Graphic inaccurate focus

    Steve, the only Graphics delivered with the stock fresnel were Pacemakers. If an older version has a fresnel, it is a retrofit.

    OP, as Jim Jones already said the stock fresnel goes in front (lens side) of the GG. As he didn't say, the ground side of the GG should face the front (lens).

  6. #6
    Nodda Duma's Avatar
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    Re: Speed Graphic inaccurate focus

    Dan, the only corollary Id add to that is, that configuration may not always provide optimal focus especially for close focus. On my Pacemaker Speed Graphic, taking into consideration the optical path lengths of the plastic Fresnel lens and the focusing glass, I found that I had to put the gg in first and Fresnel closest to user to achieve optimal focus. Otherwise, it was off just enough to noticeably affect focus for close-in stuff.
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  7. #7
    Randy's Avatar
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    Re: Speed Graphic inaccurate focus

    The OP did not state if he is focusing with the rangefinder or with a loupe on the ground-glass...or did I miss that?
    https://dl.dropboxusercontent.com/u/52893762/bigger4b.jpg

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    Re: Speed Graphic inaccurate focus

    Quote Originally Posted by Nodda Duma View Post
    Dan, the only corollary I’d add to that is, that configuration may not always provide optimal focus especially for close focus. On my Pacemaker Speed Graphic, taking into consideration the optical path lengths of the plastic Fresnel lens and the focusing glass, I found that I had to put the gg in first and Fresnel closest to user to achieve optimal focus. Otherwise, it was off just enough to noticeably affect focus for close-in stuff.
    Jason, you've just pointed to a real problem for those of us who have and use Pacemaker Graphics. Some were sold with focusing panels that contained a fresnel, other without. Both types of panel have the same casting number. The GG plus, when supplied, fresnel sits on bosses on the front (lens) side of the panel. Panels made to be used with a fresnel have lower bosses -- I b'lieve they were milled down -- than those made to be used without a fresnel.

    Fine, wonderful, except that after the focusing panels were shipped some users who bought cameras without fresnels added them. You can see the risks.

  9. #9
    Jim Jones's Avatar
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    Re: Speed Graphic inaccurate focus

    Another problem occurs when adding a non-OEM GG to a Graphic: it may not be the correct thickness.

  10. #10

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    Re: Speed Graphic inaccurate focus

    Jim, if it is mounted behind the GG its thickness makes no difference. In front, of course it will be a problem.

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