[LargeFormat] Lensboard
Clive Warren
largeformat@f32.net
Wed Dec 12 12:44:42 2001
At 11:43 am -0500 12/12/01, 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
Robert,
Ah, just what I've been doing for the last two days - trying to find
the right combination of lens board, lens, mounting ring/flange and
camera.
There are plenty of standards out there - each camera manufacturer
has/had their own. This can be a real pain. I am thinking about
standardising on a 4x4 metal board and making 4x4 metal board
retainers on the wooden boards for various cameras here.
The rear element set of any lens should be screwed completely home -
the distance between the front and rear elements is critical.
Most contemporary lenses (shutters) are designed to be fitted to thin
metal boards using a simple threaded retaining ring. If you want to
mount one of these lenses onto a wooden board then you need a
threaded front flange mount that is secured to the front of the lens
board using (usually) 3 or 4 small screws.
One alternative is to fabricate a flat metal plate with a hole in it
to accept the shutter and then mount that on to the front of a wooden
lens board. You can then use the retaining ring as normal.
Modern shutters typically do not have a long enough mounting
shank/threaded part to reach all the way through an old wooden lens
board.
Any hole drilled in a lensboard should be large enough (just) to
allow the shouldered part of the retaining ring to fit in the hole.
Make sure that the shoulder is not longer than the thickness of the
lens board though. If this is the case, reverse the retaining ring
as long as there are enough threads from the shutter body shank still
in the retaining ring it will be safe.
Steve Grimes will make almost any type of retaining ring/flange that
you can think of for a price. http://www.skgrimes.com/
Good luck.
Cheers,
Clive