Tripod Head Tests

Disclaimer: I use the word "stiffness" when I should be talking about damping. A very stiff spring can vibrate forever. I'm measuring how fast the vibrations damp down.

Some interestin seismometer results. I mounted the Fuji X-H1 with 100-400 zoom for rotational inertia. The sturdiest support I had on hand was a Gitzo 3 series with no legs extended. To make sure I wasn't just measuring the tripod, I tried a BH-30, BH-55, and a Cube. If the two RRS heads measured the same, I'd know that THEY weren't the limiting factor. In each case, I recorded there wiggly line after hitting the lens, downloaded the data, computed RMS and fit the exponential decay. The decay rates were amazingly consistent for each head. When hitting from the side, the Cube and BH-55 both showed decay rates of 3.3 to 3.5, or about a damping factor of ~3000x per second. The BH-30 had a decay rate of 1.78, a reduction of less than 100x per second! So we're not just getting the tripod.

I'll spare you all the data, but this is a typical plot of Log(RMS) over time:

Untitled by

Matthew Grayson, on Flickr

Here's the strange bit. The Cube was slightly stiffer. This puzzled me, as thecentercolumn showed the BH-55 as much stiffer than the Cube. Then I tried hitting the top of the lens. The gears in the cube control up and down motions, not rotational about the vertical axis. And indeed! The Cube came in at 2.25 and the BH-55 at over 4! (Thats 10,000x per second damping) So in the first "hit the lens on the side" test, I was seeing the best of the Cube and the worst of the BH-55 (rotation about the vertical post, I suppose). Vertically it was the other way, and the total score would put the BH-55 ahead of the Cube.

I'm still curious about what happens when the Acratech is mounted on a leveling base. Unlike the geared Arca L60 and L75, the Acratech leveling base is a ball design, and so "should" be better. We'll see!