Making lensboard (recessed?) for Schneider SA 90/8 and Synchro-Compur

[sue_deva]

Hello, all. I am in India right now and I need to install a Schneider 90/8 Super-

Angulon with a Synchro-Compur shutter in a 4x4" lensboard for a Calumet

4x5. The problem is this: I don't have a lensboard and none of the major photo

dealers in Bombay provide/make/have anything to do with them. So I need to

make one myself; I can't afford to wait for one to arrive. I have looked at

related threads on this forum and have determined that I may choose from a

variety of materials: black Lexan, aluminum, high-grade plywood--all these

seem to be plausible. I'll need to give it to a machinist or carpentry shop,

though, 'cause I don't have any tools of my own. So here are my questions:

 

Are there any materials that are more idiot-proof than others as far as cutting/

sanding are concerned?

 

Also, could one of you kindly provide the correct hole diameter for the lens/

shutter arrangement described above? I'll get a hole drilled that is 1 mm or so

smaller in diameter than the required dimension and sand it out myself

(excepting aluminum?); I'll also sand the outer edges of the board until they fit

tightly.

 

Now here is another, slightly more involved problem: I am using an old

Calumet monorail (the kind with a thin rail). It's pretty clunky and I am worried

that I will have a hard time getting much play from the movements if it is

focussed at infinity; I have read in earlier threads in this forum that there may

be problems with this particular camera/lens combination if I don't use a

recessed board. I need some pretty generous movements. So how terribly

diffcult would it be to make a recessed lensboard? I imagine I would make

some sort of 'frame' 2cm thick with outer dimensions of 4x4" and then use

other strips of the same material, perhaps 3/4" wide and oriented

perpendicular to the plane of the "frame" board, to dip into the inside of the

bellows and form a sort of box. Then I would attach to that the actual board

with the hole in the middle, which would sit inside the bellows. Would this

work? I imagine I could make the recession as deep as the distance between

the plane of the board that actually holds the lens and the front element of the

lens.

 

Thanks in advance for the help. And please keep in mind that materials and

professional machining/carpentry are very cheap here, so I would not be

averse to trying out more than one suggestion. That is, assuming I can FIND

the correct materials and somebody to cut them.

 

Thanks,

Rafil

[jim_galvin]

You are on the right track. Make the box as wide/high as possible, so that you have some access to the shutter controls. The box walls should be thin. You can make it as deep as you suggest, but don't, and inch should be enough (again access to the shutter). Another material is copper-clad printed circit board sheet, cuts easily and solders together. On the Calumet, the board sits on the lower latch, only the upper one moves, so you have to tilt the board into place. Either slope one of the box walls to allow that tilt, or replace the lower latch with another sliding one so the box can be inserted straight in. The slider is available from Calumet, you also need the two special screws, and will have to drill and tap for them. Worked for me.

[sue_deva]

I like the circuit board idea. Any idea what kind of retailer/wholesaler stocks it?

Maybe a place that repairs commercial electronics?

[deniz_merdan]

Just to let you know, i built every single one of my lesn boards(including recessed ones) with a simple swiss army knife.. and they work great.

so you dont need all those tools..

[steve_levine]

Why not order it from outside the area,and have it shipped?These are precisely machined parts,and not easily made with a "Swiss army knife".

[jim_galvin]

Circuit board material is available from electronics parts stores, electronic hobby stores (Radio Shack), electronics manufactures. I prefer the kind made with a fiberglass core, not phenolic, phenolic is brittle, breaks instead of cuts.

[ronald_moravec1]

I have built the device you require and it worked. The top of the recess box needs to be slanted as said and the official one is indeed made that way.

 

I will also say there will be next to NO movement possible. This is why they made the camera with the 12" rail. It has special bellows that allow much movement with a 90 on a flat board.

 

If you do get it mounted and focused, take care to have the front standard all the way forward or you will have a fuzzy rail in your picture. Trust me on this!

 

I built my recessed board from 1/8" aircraft plywood.

[thirteenthumbs]

The outer dege of the shutter threads is 32.45mm; the lip of the mount ring that goes into the lens board is 34.58mm. I used a digital micrometer to measure mine.

 

I made a recessed board for a Graphic View II, uses a very simular board. I used 1/8 ABS plastic. I had to taper the edges of thebox to get it into the camera. I found 5/8 inch to be adequate. Close the standards together to their limit without forceing, measure lens board to groundglass, if 100mm then an minumin of 10 mm deep board would be required to infinity focus. The deeper you make the board the more difficlt to attach a shutter release cable or make settings.

 

Charles

[see_r]

I plan to do this exact thing for a Synchro-Compur shutter on a Schneider 90mm/6.8 to go on my Shen Hao...basically my project is almost exactly the same. I may actually try to use my variable-speed, Excalibur scroll saw with a spiral blade to cut the hole using a thin line drawn around the retainer ring.

 

I will test light-tightness by putting a bright halogen light in the camera body in a dark room as discussed elsewhere on photo.net.

 

And by the way, if Deniz ever comes back to this forum, it would be great to see a nice assortment of photos he took using a lensboard made with a Swiss army knife. If the photos are good, then the construction of the lens board must have been precise enough.

 

The board I will make is planned to be equivalent to a $325 board available through B & H and so the effort is worth a few hours of my time.