Beginner question - lens board

[Chris Dunham]

Hi Folks,

I've got a technika type 4x5 lens board which has an off set hole (towards the bottom of the board) as opposed to a board with a hole in the centre. Have three lenses that need to be mounted (Caltar 90mm 6.8, 150mm 5.6 Rod, 203mm 7.7 Ektar), what difference will the off set hole board make to the use of these lenses - if any, or should I get a board with a central hole?

Chris.

[Oren Grad]

The offset drilling is standard on boards supplied by Linhof as well as on boards that clone the original faithfully. For most cameras other than the Technika, the only practical consequence is that you trade off a bit of front rise in favor of front fall. If you have a camera that doesn't have enough front rise, you might be a bit happier with a center-drilled board. Otherwise, it doesn't matter much one way or the other.

[Atul Mohidekar]

Hi Chris,

Because the of the offset hole, the optical axis of the lens and the center of the film won't be aligned. By carefully locating the position of the lens axis and the center of the film, you may be able to compensate for the offset by using shift and/or rise/fall movements (either of the lens or the back). But then you will have to be careful to ensure this new neutral position of the lens/back for every shot. In the long run, I would just get a good lens board with properly centered hole.


// Atul

[John Kasaian]

What kind of camera do you have? Can the front standard be raised to center the hole where is would be if it were drilled in the center of the board?

Is the off center hole a size that will even fit any of your shutters?

What size shutters are your lenses mounted in?

For simplicity I'd suggest finding some generic or used boards to fit your shutters.

You may be able to salvage your offset hole lensboard by enlarging the existing hole (if the lens you intend to mount on it uses a retainng ring) and epoxying a sheet of aluminium over the lensboard and then drill a new centered hole to fit.

[Chris Dunham]

Thanks for the info.

It's for a Chamonix 4x5 and all of the shutters are #0. Think I'll fill in the hole and re cut in the interest of long term simplicity. Have some devcon quick metal and alloy plate scrap so should not be too much of a drama.

Chris.

[mrladewig]

I'd just use this lensboard as is for one of your lenses, probably the one with the smallest image circle. You'll just need to have a mark on the scale for the front standard that corresponds to center for this lens. I believe my Tachihara already has such a mark on the front standard scale, but I don't have one of the offset Linhoff boards to check it.

You can see the scale in this picture and I believe the "L" marking corresponds to center for off center Linhoff lensboards.
http://www.ladewigs.com/Gallery/d/606-1/lensboard_03.jpg

All technika style boards are offset slightly towards the bottom when looking at the front of the board. For a center drilled board, the hole is centered on the opening in the front standard or the light trap ridges on the back of the lens board. I have two Shen Hao boards listed as center drilled from badger and both have the hole slightly towards the bottom edge of the front of the board, but centered in the light trap on the back. Is this how your lens board is drilled? The offset drilled ones are noticeably offset within the light trap ring on the back of the board.

[BarryS]

Chris, the Chamonix has a guide mark on the front standard for zeroing out the rise on an offset drilled Technika board. It's no big deal, so I agree with using the board as-is. Honestly, I don't think it's a big deal if there's a slight amount of rise or fall. Zeroing out the tilt and swing is much more important because that can mess up your focus if not done purposely.