I learned on this site, that the proper position for the Fresnel screen on a Graflex is between the groundglass and the lens. My Century Graphic, serial number 504 573, came without a Fresnel. But the distance from the lens side of the GG to the lens side of the flat surfaces on the GG frame that rest on the camera back itself and thus define the register, this depth is 5 mm - the same as the distance from the lens side of the film pressure plate on my Horseman RF holder to the corresponding surface on the holder, meaning that surface on the holder which rests on the camera back instead of the GG. ?? Kind regards - Hening Bettermann.

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On 2005-04-25 15:46, daddeldu wrote: I learned on this site, that the proper position for the Fresnel screen on a Graflex is between the groundglass and the lens. My Century Graphic, serial number 504 573, came without a Fresnel. But the distance from the lens side of the GG to the lens side of the flat surfaces on the GG frame that rest on the camera back itself and thus define the register, this depth is 5 mm - the same as the distance from the lens side of the film pressure plate on my Horseman RF holder to the corresponding surface on the holder, meaning that surface on the holder which rests on the camera back instead of the GG. ?? Kind regards - Hening Bettermann.

Hening, some Pacemaker Graphics (this includes the Century) with Graflok backs were supplied with a focusing panel that has a fresnel in front of the ground glass. Others were supplied with a focusing panel that has no ground glass. Within size, e.g., 2x3, the two types of focusing panel have the same casting number. They differ only in the height of the bosses on which the fresnel, if present, and ground glass sit. Without fresnel, high boss. With, boss whose height = that of high boss - fresnel's thickness.

That the panels can and have been switched between cameras greatly adds to the confusion.

FWIW, I have a Century and a 2x3 Pacemaker Speed. The Century's focusing panel has low bosses and a fresnel, the Speed's has high bosses and no fresnel.

It sounds as though your Century's focusing panel has high bosses. If so, have them ground down appropriately before adding a fresnel in front of the GG or put the fresnel behind the GG.

If I've been confusing, well that's because I AM confused.

Cheers,

Dan

Dan has it right. back before the fresnel was thought of, the frame the ground glass sits in was designed, tooling made and it went into production.

When the fresnel lens became available, all of King's horsement (or in this case Graflex's engineers) finally figured out that if they milled the the bosses down by half the thickness of the fresnel lens, the old frame would still work.

They also noted this dimension in their Trade Notes magazine to salesmen incase customers camera clamoring, insisting that they could put the fresnel lens in themselves.

Thank you for your answers, which I did not become aware of before now!
Hening Bettermann.