Originally Posted by
GrumpyDiver
Brian - I don't do macro work, so can't be specific to that field of photography, but I do some long exposure night photography, so know all about trying to keep a camera rock steady for long exposures.
There are two things to consider, the ability of your tripod and head to support the dead weight of the heaviest load, without collapsing and the second parameter is can it do so without any creep.
The heaviest normal load I shoot is just a bit under 3 kg / 6.6lb (camera, batteries, accessories and lens). My smallest tripod is rated for 6 kg / 13.2 lbs, so I in theory have a safety factor of 2 (i.e. the gear I put on it is only 1/2 of what the manufacturer states it can hold). I NEVER use it because the whole setup is simply too flexible and while it does not collapse under the weight, I know it does not even come close to being steady enough for anything other than casual shooting and I never use it for my heaviest camera.
My largest tripod is rated at 30 kg / 66lb and the head is rated at 22.7kh / 50lb. That one holds everything rock solid and I can take a 30 minute exposure without thinking twice about getting perfect registration. In fact, I've done shots that took well over 2 hours and got pixel level registration.
I'm not suggesting you need to go quite that crazy, but I would suggest you look at a tripod that has properties that are good enough for the work you are trying to do.