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Thread: Replacing Fresnel and Ground Glass on a Speed

  1. #1

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    Replacing Fresnel and Ground Glass on a Speed

    Was wondering if anyone could give me some advice based on experience regarding the proper way to replace the fresnel lens and ground glass on a pacemaker speed graphic? I've read varying accounts. Also, once done do I need to make any adjustments?

    Thanks in advance.

  2. #2

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    Re: Replacing Fresnel and Ground Glass on a Speed

    The way I understand it is this:

    The "ground" part of the ground glass is the equivalent of your film. Therefore that has to be the first thing in the glass sandwich that the light hits. Therefore the ground portion of the glass must lie in the same plane that your film will when it is being exposed to the light.

    Then the light passes through the remainder of the sheet of glass and into the Fresnel lens. The job of the Fresnel is to evenly distribute the light across the area so your eyes can see to focus and compose. So the Fresnel is the last lens the light passes through on the way to your eyes or a loupe.

    Please note, for optimal use a Fresnel is supposed to be cut to match the focal length of camera lens being used. Yes, other lenses will work, but not optimally.

    If you want to get a rough idea what Fresnel lens will do for you, pick up a cheap one at a book store. They are available to cover a full page of a book. Since they are just plastic, you can cut one down to size to place against your ground glass.

  3. #3
    IanG's Avatar
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    Re: Replacing Fresnel and Ground Glass on a Speed

    If it already has a fresnel you may just need a better screen and no adjustment's needed. If it doesn't have a fresnel then you need to fit it on the outside. A new screen and a fresnel made over 3 stops difference to my Crown graphic.

    Ian

  4. #4

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    Re: Replacing Fresnel and Ground Glass on a Speed

    Mine came with ektalite fresnel smooth side towards the lens and then the ground glass. I read the following on johndesq.com

    "It all depends if your Speed Graphic came with or wihout fresnel. Generally speaking the Pacemaker Graphics came with Ektalite mounted. When earlier SG's came with a fresnel, it is an aftermarket action.(Correct placement should be on the back, closest to the photographer that is!). All other instances, the camera is designed for an inside fresnel. In this case the fresnel should be between the taking lens and the Ground Glass.
    Drop in the fresnel with the grooved side up, next place the frosted surface of your GG in contact with the grooved surface of the fresnel. Place the GG clips.
    If you want to get rid of the fresnel, you have to shim your GG (1/3 of the thickness of the fresnel)

    Your camera had no fresnel and you deliberately want one....Drop the satin side of your new GG in first, next drop the fresnel lens with the grooved site towards the taking lens."

    Just looking to see if there is anything definitive as I've read different takes on the placement of the grooved side of the fresnel and the frosted side of the GG...

  5. #5
    IanG's Avatar
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    Re: Replacing Fresnel and Ground Glass on a Speed

    If your camera came with the Ektalite (Kodak) fresnel it has to be fitted in front of the screen, any other after market fresnel would go in the same position, but would need to be similar thickness.

    Your quote is generally correct.

    Ian
    Last edited by IanG; 30-Sep-2013 at 15:05. Reason: typo

  6. #6

    Re: Replacing Fresnel and Ground Glass on a Speed

    I have a basic question: i own a speed graphic with a serial number of 977422. It came with a fresnel when i bought it at an antique shop. Is this fresnel the Ektalite ones from Kodak?

  7. #7

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    Re: Replacing Fresnel and Ground Glass on a Speed

    If the fresnel is positioned so that the smooth side is facing the camera lens, then it will almost always be a Kodak Ektalite. It should be in front of the ground glass, contrary to the usual advice for other cameras, which is ridged side pointed toward the front, behind the gg.

  8. #8

    Re: Replacing Fresnel and Ground Glass on a Speed

    thanks; that is the way it is now, however, there are scratch marks on both sides of the fresnel from film holders, so i guess it was switched around at some point. Anyway, can i replace this fresnel?

  9. #9

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    Re: Replacing Fresnel and Ground Glass on a Speed

    The scratch marks in my experience are present on all of them that have been used.

    I do have one back that I went whole hog on. A mid-grade Maxwell screen. But because of the unusual backwards arrangement Bill M. told me I had to have the back machined to have an accurate plane of focus. I did that. I must have been into it for $500 and I guarantee you it would be much more now.

    So I suppose the question is: replace it with what? If you put in a new gg, with a fresnel that isn't an Ektalite, you may (and veryu likely will) have a plane of focus issue.

  10. #10

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    Re: Replacing Fresnel and Ground Glass on a Speed

    Quote Originally Posted by Kevin Crisp View Post
    The scratch marks in my experience are present on all of them that have been used.

    I do have one back that I went whole hog on. A mid-grade Maxwell screen. But because of the unusual backwards arrangement Bill M. told me I had to have the back machined to have an accurate plane of focus. I did that. I must have been into it for $500 and I guarantee you it would be much more now.

    So I suppose the question is: replace it with what? If you put in a new gg, with a fresnel that isn't an Ektalite, you may (and veryu likely will) have a plane of focus issue.
    the ground glass is the same thickness as the original fresnel. you can just flip it around and mount a new fresnel behind it.

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