[LargeFormat] Lensboard

[Les Newcomer]

rules were ment two be broken and it seems the myriad of camera makers
took this to heart.

For the most part, wood lens boards were around 1/4" thick. Larger
heavier portait lenses on huge studio cameras go thicker boards.

For metal lens board the max thickness is usually aroun 1/8" or a bit
less. This is true for most of the Calumet/Toyo aluminum boards.  Sheet
metal boards found on press cameras like Graphic Horsman Toyo are much
thinner than that.

The hole in the board should fit the shoulder of the retaining ring.
This way you can send the millwright/ lathe hand the board and the ring
and not have to worry about what he sets your lens on while working on
the board.

As you might have figured out, retaining rings are designed to be
mounted from the back on thin, usually metal material.  Flanges, those
rings with screw holes, are designed to be mounted in wood from the
front and can handle any thickness of wood or metal.

Putting a retaining ring on a wood board is difficult as the board is
too thick and there aren't enough threads on the shutter. A counter-bore
is made to reduce the thickness of the board to the max thickness that
will allow the retain ring at least one full turn and usually 1.5.
Sometimes I've had to bore a large hole in the wood then screw/epoxy a
piece of sheetmetal to the board and bore a hole for the lens in that.
Robert Mayrand wrote:
> 
> Hi!
> I know there is no standard in board size but is there any in board
> thikness. I'm using a large format camera for the first time and have to do
> a board and mount the lens.
> 
> Are we suppose to screw the back element as far as we can. On my lens the
> retaining ring is pretty thick if I screw the element as far as I can with
> the ring it leaves less then 1/8" and it seem pretty thin.
> 
> The size of the hole also raise some concern. The ring has a shoulder wich
> goes to 1 5/8". Should I do the hole of this side. Or to the actual smaller
> thread size of the lens.
> 
> MY lens is a Symmar-S 180mm mounted in a compur 1
> 
> Thank you for you help.
> 
> Robert
> 
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