A question for Bjørn...

[CS]

I would buy a long Arca compatible rail, 300 or 400mm, fix it on camera and carve 1 or 2 pieces of wood to support the lens, screw them to the rail and apply large amount of gaffa tape everywhere possible. These rails do have many holes for screwing and additional rigidity can easily be gained by screwing 2 rails together or by screwing additional metal plates to the rail.

What am I missing here? Arca compatible brackets for cameras and lenses run perpendicular to one and another, so how would one rail work for both camera body and lens?

[pluton]

The idea, as I understand it, is that the camera and lens would be directly screwed to the rail, rather than placed in Arca type clamps. 
However, the camera and lens will inevitably mount at different heights from each other. I propose just securely mounting the lens...via one or two sculpted wood blocks... only to the plate.  A additional clamping piece, either metal hose clamp(s) or a matching sculpted wood block would need to used to secure the lens downward to the bottom wood block and the rail below.  A crude concept sketch:

[CS]

I don't have any collared lens experience, but wouldn't the wooden blocks block zoom and focus control rings?

I thought that Bjorn's remedy was to clamp down from the tripod collar area of the lens  leving the controls accesible.

[David H. Hartman]

 The lens cradle shown above is for a PN-11 and additional extension tubes. What I suggest above would join a dSLR L-Plate and lens collar in a similar way.

Dave

[Bruno Schroder]

The idea, as I understand it, is that the camera and lens would be directly screwed to the rail, rather than placed in Arca type clamps. 

Exactly, and indeed a block under the camera to keep the lens from sliding axially. The gaffa tape helps also in that respect. Thanks for clarifying, Keith.

I don't have any collared lens experience, but wouldn't the wooden blocks block zoom and focus control rings?

There is space between the 2 rings and I would remove the collar anyway. You don't need the block to be large to stop vibrations. A L shape would provide enough space for screwing on the rail and a thinner support between the rings or on the collar space.

[CS]

I passed on the info to my friend and here's where he is on this:

"I’m thinking of designing my own front and rear support system. I’d have to get the three pieces machined.
It would mean giving up horizontal alignment, which was an original constraint, but I can do Polar alignment instead.

The real issue is figuring out all the measurements - I need to see if the tripod mount-to-sensor centerline is published anywhere. If not, I’ll need to measure, machine everything a bit small, and use shims."

I dunno if anyone can tell me the "tripod mount-to-sensor centerline" measurement, but perhaps Bjørn or Roland might have it.

Thanks to everyone that has responded, it all helps.

[Matthew Currie]

Thinking out loud so to speak, on Bruno Schneider's idea, if the long Arca plate has 1/4 inch threaded holes in it especially, one might be able to get screws and threaded collars.  There exist collars, that are essentially a tube an inch or two tall, threaded internally,used to join two pieces of threaded rod together.  One of these and a couple of screws can make a sort of inverse turnbuckle, in which the lower end is screwed directly to the pad, and the upper end screwed out to provide pressure.  Put a rubber cap or the like on the head of the upper screw, and raise it until it presses on the lens barrel.  Do that at a couple of different places, and it should keep the lens from rocking on the mount.

[CS]

Posting error.

[David H. Hartman]

What am I missing here? Arca compatible brackets for cameras and lenses run perpendicular to one and another, so how would one rail work for both camera body and lens?

The plates generally have a 1/4-20 fitting or two so they can be attached to a long Arca-Swiss lens plate using those features. Spacers would most likely be needed to line the lens collar and camera or camera L-pate. Care is needed to see that there is no stress on the bayonets. I'd use 6061-T6 bar stock though if wood working equipment is available hard maple should work well.

Dave

[CS]

He has come up with his own design, and sent me a couple of PDFs, but they don't copy and paste here well.

[pluton]

Seems like rubber and gaff tape should be avoided if possible, since they are not rigid.
Carl, if your friend doesn't mind showing it here, copy the PDF as a small (sub-megabyte range) JPEG and it'll post right up.

[CS]

Seems like rubber and gaff tape should be avoided if possible, since they are not rigid.
Carl, if your friend doesn't mind showing it here, copy the PDF as a small (sub-megabyte range) JPEG and it'll post right up.

Send me you email address and I'll email it to you.  Can't seem to get it posted.

[CS]

Lets try this again. Here's the pdfs of his design that he sent to me yesterday.

[CS]

Finally! Converting pdf to jpg was the culprit. Thanks for the suggestion, Keith, that did the trick.

My friend has a friend with a CNC machine, so he is going to ask for a quote to get the pieces fashioned, then he will drill and tap them at home.

[Peter Connan]

I have a cheat, though probably not as good:

Insert a suitably trimmed wine bottle cork between the lens and the foot.