I was hoping this had already been covered. maybe I didn't search well enough? At any rate, here is where I'm at.
I now have a really nice Osaka (Tachihara) 8x10 field camera. It came with a lens in an abs or some type of plastic lens board that is slightly too thin. The easy/temp fix for this is just a few more strips of book binding tape to get things snug. Problem 1 solved.
Problem 2 is my other lenses.
There looks to be a well-regarded maker of wood lens boards on ebay. I'm guessing it would take a week to ten days for me to get a few boards in hand.
I have some random selections of thin plywood around, so I thought I would try and make a few boards myself. While digging through my materials stash, I happened upon a sheet of aluminum I had forgotten about. It also happens to be the perfect thickness. when I set a piece into the front standard, it locks in nice and tight with no wiggling.
So,
Is the decision to mount the lens off center in the board driven by focal length of lens or camera (bellows shape?) or some of both?
If I have to machine a thinner section around the shutter hole to properly mount the lens (due to mount thread width), I'm not sure how to accomplish that with aluminum and the tools I have at home.
If you think of a traditional wood field camera lens board with its rabbet around the mounting perimeter, is there any problem using a perfectly flat board instead if it sockets in nice and snug?
Whether a lens is mounted in the center or off center in the board is driven by the design of the camera. Linhof cameras have focusing tracks stacked one upon the other. This raises the lens by 7 or 8mm. To make the lens centered on the focusing screen. the shutter mounting hole must be lowered by the same distance. Check your camera's front and rear centering and drill the hole accordingly.
To avoid machining a thinner section around the hole use a flange like this one: https://www.photrio.com/forum/threads/fs-lens-flanges.198197/
The rabbet around the lens board mounting perimeter matches the inner frame of the lens panel on the standard and acts like a light trap. It may be better to have it to avoid light leaks.
Kumar
If I have to machine a thinner section around the shutter hole to properly mount the lens (due to mount thread width), I'm not sure how to accomplish that with aluminum and the tools I have at home.
Wouldn't the offset also reduce the amount of tilt and fall since the image circle is in another area rather than centered?There are different varieties of carbon fiber, Alan. Some of it's headache to work with compared to aluminum in terms of smooth edges. The thin type used for this kind of project is fairly easy to cut. I prefer working with thin PC board, which has a thin phenolic or fiberglass core sandwiched inside two outer copper layers. It's easy to fabricate with the right blade or scoring device, and stays very flat. It accepts metal primer and paint well. But I personally wanted a cool looking ground glass protective cover for my 8X10, so did a true verdis gris upon copper random swirl effect on it, then sealed over it with acrylic varnish.
MTG - an offset hole can be used to obtain a little more rise to the lens than the front standard would normally allow. But otherwise, I see no sense in having one unless it came free with the lens. All mine are center hole.
What you might be interested in is what I did with maple. I wanted a very solid dual-mounting rail for a big Pentax 300EDIF tele lens, which needs just as much support as my 8X10. Since the tripod involved is my large maple Ries, a real veteran piece of equipment with plenty of battle scars to prove it, after I epoxy laminated a thick piece of maple rail to black Garolite phenolic and installed the stainless thread inserts, I pickled the wood with penetrating epoxy with rust mixed in, to match the weatherbeaten look of the tripod itself. My 8x10 happens to be a Phillips, which was made of custom fiberglass/maple ply treated with marine penetrating epoxy. That has yellowed over time, so I thought it would be fun to cosmetically match everything. Then when it tote that around in a vintage 70's true California-made Kelty external frame pack, I get a lot of compliments.
The only sapele I have on hand is in the form of some Festool Domino mortising tenons. Instead of using these blind, I'll due a through mortise and leave a tenon end exposed, contrasting its deep mahogany color with the blonde maple sheet material itself.
If the camera would normally use a centred board, having the lens off centre toward the top is like having front rise built into the camera, which could just be for convenience for architecture photography. Yes, it would limit the amount of tilt, since the image circle at the focal plane would be centred higher on the ground glass.
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