The Acratech Ultimate is an innovated design; instead of the ball
being captive inside a nearly solid housing, the ball is captive between
two semicircular parts. The two parts fit together to fit around
the great circle of the ball; the clamps are attached to the base at a
45 degree angle, so that the 'front' of the head forms what is
essentially a very wide drop slot.
The bottom part of the head includes a pan collar; the pan collar is
locked with a relatively small rubber faced knob. Exerting a
reasonable amount of force on the knob seems to lock the pan collar
securely.
The other two controls on the ballhead are the minimum drag knob
(located at the top of the ballhead), and the main drag knob (a large,
rubber covered knob at the bottom of the head). The minimum drag
knob is quite small, located in a place where it's difficult to adjust,
and is very hard to turn. No scale is provided so that the minimum
drag can be set to specific values. The main knob is easy to grip
and turn, and is well located so that the other controls (and the QR
clamp) don't interfere. In a nice innovation, Acratech offer the
Ultimate in both left-handed and right-handed versions - an approach I
wish other ballhead manufacturers would adopt.
It's about half an inch shorter than the Arca-Swiss
B1.
The Acratech Ultimate is nicely made, with great manufacture and a
nice finish. The sample I tested was about 22 grams lighter than
spec, so it really is that light. The downside is
what you give up to get that low weight.
First, the minimum drag adjustment knob is just too darn small to be
useful. This, combined with the very small ball and the limited
surface area in the ball clamping arrangement make me very worried about
camera flop. Maybe I'm paranoid but having had several thousand
dollars worth of camera and lens nearly take a swim in a river as a
result of a flop, I'm pretty leery of any design which doesn't do
SOMETHING to prevent flop.
Second, I really don't care for the clamp. It's a knob/screw
arrangement, where you unscrew the knob to loosen the clamp, and tighten
the screw to close the clamp, just like most other ballheads. The
difference is that the threads are very coarse, presumably so that you
don't have to turn the knob much to open/close the clamp. But it
left me with a very uncertain feel about how secure the clamp was.
Finally, there's a spring loaded 'safety' pin set into the top of the
clamp; I assume that this pin is located to prevent appropriately
machined plates from sliding endwise out of the clamp. Alas, I own
plates from different manufacturers, and none of them match the pin
location. Instead, the pin is just a nuisance.
The open design of the Acratech Ultimate seems like a dual edged
sword to me. On the one hand, it seems like it would be easy to
clean dirt, grit, and salt water off the ball easily. On the other
hand, the completely exposed design means that salt spray and wind-borne
dirt and grit can get at all the surfaces of the ball, so it's more
prone to get dirty.
On the Acratech website there's a photo of a '30 lb weight test',
which shows the head holding position despite the application of 30 lbs
of force. I'd note that the test shows the force being exerted as
rotation around the axis of the head, rather than the usual force
exerted downward toward the front of the camera, as will usually be the
case. In any case, without some discussion of the moment of the
force, the test doesn't mean much. In my testing, the Acratech
Ultimate seemed to hold position well, but not any better than heads
with balls of similar size (the Linhof Profi II, or the RRS BH-40, for
instance).
The Acratech Ultimate Ballhead sells for US $279.95 direct from
Acratech. There's also a long list of retailers on their website:
see http://www.acratech.net.
