Please explain lens board hole sizes to me?

[ckpj99]

There's plenty of information about this, but it's scattered in the winds of the internet, which makes it impossible for me to figure out.

So I currently have two lenses and one lens board.

Lens 1 - Schneider Symmar 210mm f/5.6 (the one that "convertible" into a 310mm)
Lens 2 - Kodak Ektar 127mm f/4.7 (it's old and came with my Speed Graphic)

Both of these lenses fit in the one lens board that came with my camera. Both are mounted in what appears to be the same size Compur shutter. Copal 0? Copal 1? I have no freaking idea. But I assume that this size sorta dictates the lens board size needed.

The threads (the ones that actually go through the lens board hole) on the back of the Symmar and the Ektar are 39mm in diameter. The hole in the lens board is slightly bigger at 39.5mm or so.

So I want a new lens board. I got to KEH and look around. I see Graphics Press lens boards and a couple Graphics View. I assume I need the Press. I then see several options for hole size - 29, 32, 34 and 35.

What am I looking for? What "mount size" lens do I have? What lens board do I have? What lens boards should I buy to match my existing lenses?

Thanks for your help!

[lenser]

The lens board and it's physical size are dictated by the camera you have (unless you buy an adapter board for blending your camera with a different manufacturer's board). As you've already guessed, the hole size is dictated by the shutter and it's needed opening to allow the lens to be mounted. Why not call KEH, and tell them what camera you have and what lenses and let them help you make the right selection?

[Leigh]

The required mounting hole for Copal shutters (#0, #1, and #3; there is no #2) are
larger than needed to pass the threads on the shutter.

The reason is that the retaining ring that screws on the back has a ledge on the shutter side.
That ledge is supposed to go through the hole.

I don't know if the Compur shutters use the same style of retaining ring.

- Leigh

[Roger Thoms]

Since you have a board that both shutters fit you already know the size. You can either keep looking till you find the correct size or another possibility would to buy a board that is slightly smaller and enlarge the hole. You could also buy a blank board and bore it out to the correct size. Here's a link to a thread that shows how with basic tools, go to post #15. http://www.largeformatphotography.in...a-spacer/page2

Here is a link to Compur shutter sizes that confirm your measurements. http://www.skgrimes.com/library/used...hutters/compur

Hope this helps.

Roger

[Mike Anderson]

http://www.largeformatphotography.info/shutters.html

About 4/5ths the way down is some shutter hole size info. Below that it says

This refers specifically to Copals. Post WWII Compurs are the same except for tolerances concerning the front to rear lens cell flanges distance

[richardman]

I am a newbie too, so perhaps my newbie answer may be of use: different cameras use different lensboards. For example, Linhof-Technica is one of the most popular one, adopted by a few camera makers. If you do some googling with your camera, you will find what lensboard it uses.

The size of the hole is shutter dependent.

One major source of confusion is that everyone talkjs about Copal #0, #1, ... #3, but KEH uses the size of the opening, e.g. 35mm is Copal #0, 44mm and 64mm are #1 and #3, I think. Not sure about the opening of other shutters, but I'm sure one of the sites linked in the one of the earlier replies have the explanation.

You also have holes that are offset toward the bottom. I am sure there are good reasons to prefer or to avoid them, I'm too lazy to google it though. A couple of mine have that.

You also have recessed lensboard. This is mainly for wide angle lens and for the case your bellow may not draw short enough. e.g. if your bellow only goes as short as 90mm, using a recessed lensboard may allow you to use a 75mm lens.

Hope this helps.

[ckpj99]

Ok, I think I got it. I lucked into have two lenses with the same shutter. Finding a matching pre-drilled lens board is going to be really unlikely because the shutters I have are not Copals.

So I either need to luck out into a lens board or drill a new one.

My next lens will be easy because it probably won't have a weird shutter attached to it.

Thanks folks!

[Joseph Dickerson]

It sounds like you're over complicating things. Just measure the hole on one of your boards.

It should match one of the "standard" sizes regardless of the shutter brand.

Of course I just over simplified things, but most modern (post war...WWII that is) lenses will fit one of the standard (#0, #1, #3) shutters.

JD

[Leigh]

Call KEH. Tell them what kind of camera you have (you haven't mentioned that in this thread) and what shutter.

They probably have lensboards in stock that will match. They have a huge inventory of such things.

- Leigh

[cowanw]

You said you had a speed graphic so here will be the description of your board.
http://www.skgrimes.com/products/lens-boards/graphic