Are you using an M10 or M20? I have both; the M20 pan lock is much more secure if that is what you are after. It is also a little better damped, if that is the right description of the difference. Although I have tried a number of different ballheads in the field, I would not do that kind of stress test on a stranger's gear, so I have no basis for comparison. Between my M10 and M20, though, the biggest difference is the pan lock.
When I bought my M10 3 years ago, I was told that I should not carry a lens over my shoulder with tripod attached. (this should be searchable on the Nikonians.org tripod forum archives). There was concern it may damage the pan base. Since I don't do that, I have no need to lock it down that tightly.
Since I am not doing that, the smaller pan lock knob is not an issue. I'm not trying to do something (white knuckle tighten the pan base) that it was not designed to do. One of the great advantages, to me, of the Markins layout is that I can have both controls on the left side, and dedicate my right hand to the camera. That is an important feature. If the pan lock were larger, I don't think they could physically do that. I would not want the controls moved for the sake of a larger knob. That's just a trade-off of features- pick one. You cannot work a BH-55 with one hand. The Knobs are 180 degreees apart. That is actually one of the main reasons I never bought one. The Kirks are small, and because the pan lock and tension limiter are the same size they could be easily confused by feel, resulting in a catastrophic flop. The Arca-Swiss heads are substantially identical to the Markins in terms of location and knob size. Only the RRS heads have large pan locks and they are 180 degrees from the ball lock.
I have also found, via a substantial number of tests, that the M10 in particular performs better (less vibration) when it is shot with the pan lock fully loose. The only reason I lock the pan is when I need to change a camera setting or are otherwise concerned about losing the framing on a scene. I have to bump the lens pretty hard to make it move, especially with the M20. In that event, I'm happy the pan base gives instead of my long lens.
Because of all that, I don't find the pan lock to be an issue but, for someone that requries an absolutely tight pan lock down, that would be an issue. AFAIK, my experience, and I guess your experience, is normal and I am told that Markins designed it that way. True or not, it is apparently just the way it is.
I'm not Messianic, honest. I like the Markins heads. When I recently acquired the M20 I seriously consisdered a BH-55 but there is no such thing as perfection and, on balance, I prefer the Markins.
Neil
Despite the almost Messianic enthusiasm of some here for the Markins,
it is not without issues. The pan lock is poor, and slippage is
common. I don't think it is possible to lock it down to prevent a
large lens from rotating when being carried. The pan lock is also
painful to use being small and made of metal with a knurled surface.
I would rate the pan lock as okay but I would expect better at the
price. Otherwise this is an excellent head. The captive knob fell off
my QR platform, but I think that was a manufacturing fault and not a
design problem.
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Regards,
Neil