[BobinKy]

How much does a tripod's stability affect the observer's ability to acheive fine focus with mounted binoculars or a spotting scope?

I switch between two tripods when I observe with my binoculars and spotting scope.

Bogen 3001/3126 tripod/head -- carry in the field tripod
3001.....11.1 lb. load limit.....3.6 lb. wt......55" max ht.
3126.....8.8 lb. load limit.....2.2 lb. wt......4" max ht.

Manfrotto 3246/501 tripod/head -- stationary tripod
3246.....26.5 lb. load limit.....8.3 lb. wt......68.5" max ht.
501.....13.3 lb. load limit.....3.4 lb. wt......4.2" max ht.

I have noticed that I sometime have difficulty achieving fine focus with my medium size binoculars and spotting scope (3 lbs-5 lbs) on the lighter 3001/3126 tripod/head that I carry in the field--even though I am well below the load limit. This focusing difficulty is not experienced as much on the heavier 3246/501 tripod/head.

Is there is a rule of thumb to follow when matching instrument weight with the load limit of the tripod/head? (For example, keep the instrument weight under specific % of the tripod/head's load limit.)

I appreciate any comments on this question.

...Bob
Kentucky

[bughunter]

Not only the size is important, also the tripod material. If it's possible, avoid aluminium. Take a carbon, even with higher price. It is not only lighter but also absorbes vibrations (from wind or touching the tripod) much better. Wood is also good, but heavier.
Please see: http://www.tvwg.nl/testrapporten/sta.../statieven.htm
I was really supprised, how long an aluminium tripod needs to settle down.
Its not in english, but you will understand the pictures and can use a translation service.