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Compared to a Kirk are they about the same regarding performance and ease of use etc?
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Not at all. I have been able to test a Q3 vs. a BH-1 (though I suppose comparing it to an M10 is more accurate).
BH-1 advantages:
- Much better stock clamp. The camera doesn't usually cover up the spirit level (if you care about using the spirit level). The Kirk clamp is better machined, with no exposed springs or voids when the jaw opens. Very nice design. Quite a few Markins buyers don't get the stock clamp.
- The pan lock locks much tighter with less effort and is more progressive. Markins heads tend to be an on/off affair and you can often budge the pan after it's locked if you exert enough force (some will say excessive force). Sometimes you have to hurt your fingers a bit to really lock the Markins.
Q3 advantages:
- Much smoother throughout a much wider range of motion. The Kirk becomes fairly jerky in movement if you tighten the tension to a point where it doesn't droop in a 45 degree position, but then move the head back up to 0 degrees. Markins heads are smoooooth.
- Much smoother pan action. I tried three different, brand new BH-1's and one older-gen used one -- their panning is not particularly smooth.
- Much more compact and lighter.
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I wouldn't characterize the following as advantages because they are based on how one prefers to work with a head.
The Kirk is basically a "two-brake, two-knob" design. The tension control is with a separate knob, and applies force to the ball with a separate brake than what the main control knob uses.
The Markins (and Arca Swiss) are basically a "single-brake, tension limiter" design. That is, the tension control knob simply limits how far you can "open up" the main control knob to unlock it. E.g. you can set it so that you can't loosen the ball enough to cause your gear to flop.
Most Markins and Arca Swiss users obviously prefer the tension-limiter design. Some people think that having a separate tension knob has the risk of "knob confusion" and letting your gear flop by turning the wrong knob. Some people like separate tension controls and actually use the tension knob as a lock-down knob.
The BH-1 and Q3 I tried do creep somewhat on lockdown. The BH-1 creeps a bit less if you follow the prescribed order in setting tension (it's a bit unintuitive at first).
