Like to have some opinion on my issue.
When i mount my D90 + Sigma 50-150 (non-OS) on my tripod (Benro C0690M8, rated 5kg),
i can see the image slightly jerking up and down when viewing thru the optical viewfinder.
The weight of my setup is 0.7kg + 0.8kg, well below the tripod load,
though the lense is a bit long & doesnt come with a tripod collar.
Will upgrading a tripod head helps in my situation ?