I posted this on another thread but as that was model specific I thought I might re-post it here for any other newbies like me that might be interested, and making the same mistakes as me.
On the weekend I was playing with my remote release and the new to get used to them, I was using LiveView for a change instead of the viewfinder because I wanted to try the 10x zoom on the screen in LiveView to see what bit was focused. I was using my 7d and 70-200 IS f4L .
I noticed that using the LiveView zoom in what looked like a stable image through the viewfinder or not zoomed in on the LiveView was drifting around a bit, I checked all the locks and ball head locks and all were tight. plus the was outside on solid ground.
I went in to look through my manuals and the first one I read was the manual which said you MUST switch Image Stabilisation IS off when mounted. So I went back out using the same settings and watched it with the IS on and it wandered, and Off and the image went rock solid.
I know for the experts this is obvious, but I think for any beginners out there like me it's worth sharing as there are that many settings on these things that there is a lot to take in at first and its easy to miss something. Maybe for some this might be a cause, especially on close range stuff, for the focus not being where you thought it was or slightly blurry images.
NB - you can only see this when using LiveView and zooming the Live View screen, just through the view finder or normally on LiveView it all looks steady as the motion produsced by the IS is very small.