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rbk61
30-Sep-2013, 12:11
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.

AtlantaTerry
30-Sep-2013, 12:17
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.

IanG
30-Sep-2013, 12:18
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

rbk61
30-Sep-2013, 13:19
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...

IanG
30-Sep-2013, 13:35
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