Saturday, March 23, 2013

Tripod head adapter

This is an adapter for a ball-head tripod for use with a spotting scope. A ball head works great for a camera, but not so great with a spotting scope -- it's tough to aim a scope when you loosen the ball and everything gets all floppy. This adapter adds a vertical plane tilt mechanism to the top of the ball head. Just lock the ball tight and use the tripod's pan (rotation) and this adapter for the vertical.This setup allows me to have both options -- a pan/tilt for the scope and a ball head for a camera, without carrying a bunch of gear. Plus, the pan mechanism that came with the tripod on the ball head is amazingly smooth, so I get to use that with both heads.

It has an Arca type dovetail quick-release plate on the bottom that attaches to the ball head on the tripod, and a clamp on top to attach to the scope.

The center pivot block is solid acetal plastic, or Delrin and the rest is aluminum. The acetal against aluminum provides a silky smooth motion.

Tilt adapter breakdown

The clamp and plates are compatible with the tripod hardware. The springs fit into holes on either side of the screw and parallel to it to keep the clamp open when not tightened.

Arca type clamp

The plate on the left goes on the bottom and is relieved to fit a locking pin in the tripod head's clamp. The one on the right fits on the scope and attaches to the top.

arca type mounting plates

It works great. Smooth tilt, easy to use. I can pop the whole scope / adapter assembly off and use the ball head with a camera.

Tilt adapter with scope mounted

And here's the tripod with the scope and top assembly removed, and a camera on the ball head. It works very well and only takes a few seconds to switch.

Adapter removed, camera mounted

When I started I figured I could find some standard dimensions for Arca Swiss type dovetail quick-release clamp and plate. I didn't have much luck, so I'll share what I came up with. These are what I used, but I had to tweak the clamp side a bit to make it fit. They should be a good starting point, but use them at your own risk. I have no idea if the Promaster tripod they were based on is a standard size.

Arca type dovetail quick release plate dimensions
I used a couple of 3/32" drills to measure the dovetails (actually .094" dia)

Arca type dovetail quick release clamp dimensions
The clamp side dovetail needed to be cut more than shown here to fit the plate.