[Leica] Checking a tripod for resonance

[reviews_ed.hifichoice@dennis.co.uk (Alan Sircom)]

While evaluating the performance of a tripod with a glass of water is a
very good idea, remember that water doesn't have a mirror and a shutter
to set up its own set of internal vibrations. If these vibrations just
happen to be harmonious with the resonant frequency of the tripod, it
will tremble a little. 
Unfortunately, the only practical way to check this (unless you have
access to accelerometers and the like) is to use your camera and lens
with the shutter open focussed on something like a single LED in a
darkroom. An exposure of about a minute or so will do it. You may have
a bright LED, but if you have a large, defocussed LED they you have
camera-tripod resonance. What's more, in an ideal world, you should
check this with every camera and lens combination you use on a tripod,
as each will subtly change the resonant signature of the bit that fits
on top of the tripod.
tFortunately, we aren't all perched on a rock in Yosemite with a dirty
great big 10x8 camera and the sort of internal vibrations caused by the
clunk of a Leica mirror and shutter are unlikely to set off a tripod.
So this all may be a little too anal for most (myself included).