Center or Off Center Lensboard

[thread]

I am currently looking into ShenHao lensboard (linhof compatible), I found out linhof has different kind of configuration for their lens board. Center and off center. What are the differences with these board?

[Bob Salomon]

Linhof only has one configuration (except for a couple of lenses in 3 shutter with a very large rear element. The normal hole position for a Linhof 45 Technika board is off center. This guarantees that the optical center of the lens will be centered on the center of the gg with Linhof cameras when the front standard and the rear standard are in their 0 position.

[Bob Salomon]

The difference for the board with a different hole position is that the hole is raised up by a couple of mm so the lenses that need it can be properly mounted onto the camera.

[thread]

Thanks Bob. :)

[Songyun]

Bob, Do you have the exact number of mm that the center of the hold off from the center of the light trap?

[Bob Salomon]

Bob, Do you have the exact number of mm that the center of the hold off from the center of the light trap?

No, Marflex may.

[Songyun]

No, Marflex may.

Do you have contact info?

[Bob Salomon]

Do you have contact info?

marflex@aol.com

[Songyun]

Thanks!

[Peter K]

Do you have the exact number of mm that the center of the hold off from the center of the light trap?
about 5.8mm

[Bill_1856]

Even offset, they often still aren't centered on the ground glass. It's hard for me to reconsile this with my knowledge of good German enginering practices. I think it's a problem which presented itself due to the need of adapting the new front standard and three layers of tracks to the old Technika body, without requiring new body castings, or an articulated front door.
In practice it doesn't matter very much with most lenses, so long as they have adequate coverage. However a few lenses, (such as the 90mm Angulon), which barely cover 9x12 Cm may vignette the bottom of a vertical shot with used to shoot 4x5.

[Peter K]

Even offset, they often still aren't centered on the ground glass.
This is possible a problem with lensboard clones.

The front standard for the Technika IV 4x5" (and newer cameras) was constructed to accept lenses mounted on a reccessed lensboard as discussed here (http://www.largeformatphotography.info/forum/showthread.php?t=47832). Specially to use the Angulon 65mm with RF. So the flat lensboard with it's off-axis hole is only a simplified version of the recessed board.

If you mount an original Linhof board with centering hole to a properly aligned front standard of a Technika IV (or newer) you can see the small hole meets the center of the ground-glass.

[Doremus Scudder]

Cameras other than the Linhof often have the lens centered in the board. I'm not sure about the Shen Hao. The idea is to have the optical center of the lens centered on the film when the camera is set at "zero" position.

That said, I have found that an off-center lens position can be helpful with cameras designed for a centered lens, especially if the camera has limited movements. With a centered board, when you run out of rise or fall, you have no other option except to point the camera up or down and tilt both back and front standards to parallel. This works, but is a bit fiddley. With an off-center hole on a camera designed for a centered one (like maybe the Shen Hao...?), the slightly lower hole gives you a bit more effective fall. And, by simply mounting the board turned 180°, you gain a substantial amount of extra rise. This was enough to convince me to get all my boards with offset holes.

Best,

Doremus Scudder

[Deval]

So are all boards for shen hao needed to be offset for centration? I've gotta pick out some lens boards for the TFC617a, and I'm trying to decide ...

[Jac@stafford.net]

So are all boards for shen hao needed to be offset for centration? I've gotta pick out some lens boards for the TFC617a, and I'm trying to decide ...

You can use the standard Technika (and Wista) lens boards which have the lens hole ~8mm offset low, and if you wish you can nudge the rise that much to center it. Dimensions of Technika boards to fit the TFC 617 A are 96mm X 99mm and ~2mm thick.

[Deval]

ahh so to have it centered in the zero position would required a centered board for that camera