First efforts with a big prime (1 Viewer)

I received my sigma 500mm f4.5 yesterday, along with a new manfrotto 393 head to put it on. These are some of my efforts while getting used to the handling of the new combo. http://www.birdforum.net/gallery/showphoto.php/photo/155838/cat/500/ppuser/28570
http://www.birdforum.net/gallery/showphoto.php/photo/155840/cat/500/ppuser/28570
http://www.birdforum.net/gallery/showphoto.php/photo/155841/cat/500/ppuser/28570

Some threads on the 393 head mention vibration as a problem - my first impressions are that with gentle hand pressure on the camera it isnt too bad, but I might add a bean bag sat on the tripod foot for more damping. The lens just blew me away - all these are with the lens wide open and iso set at 400, as I wanted to get a good idea of how it reacts to different lighting etc before changing camera settings around.
Comments and advice welcome.

Excellent, Gordon. Shouldn't be many excuses with that camera and lens
Yes, a beanbag atop the lens helps...and a further hand on that helps even more, although I found that's only really needed when using teleconverters.
Good to see the 393 still impressing new users of it, you'll find the big benefits when doing birds in flight.

cheers,
Andy

looks like you've got off to a good start with it Gordon (it's nice to know it's in good hands)...

Personally I found that it took me a while to get used to using a big lens, the size and weight of it can make getting quick shots tricky. Trust me it gets better with time, and using a decent tripod and gimbal head will help a lot, especially with flight shots. As you've already found the lens is sharp wide open, but beware of the very shallow DOF when shooting a close subject. The best thing is to just get out using it, I'm sure you'll find it lets you get shots that the 50-500 just would not get. I'm looking forward to seeing the results over the coming weeks/months.

Thanks guys. It's certainly a different handful to the bigma - I think handheld flight shots will be a rarity! Mind you, the gimbal head makes panning a lot easier. As you say, it will take a while to get used to it, but I'm looking forward to the challenge.
The shallow depth of field caught me out today - a lovely showy grey wagtail at about 20ft, with pale green reflections on the water behind it, and unfortunately I just missed the critical focus point. That said, I wouldnt have even attempted a shot with the bigma - in deep shade under a river bank, so it's still one to the good!
Here's two from today - a better focussed one of the wagtail, and a nuthatch that refused to come close! I have found it changes things quite a lot, being tripod-bound, but being less mobile did get me sitings of several birds I would have otherwise missed, and even a close view of a weasel (on the wrong side of the camera unfortunately!)
http://www.birdforum.net/gallery/showphoto.php/photo/155992/limit/recent
http://www.birdforum.net/gallery/showphoto.php/photo/155993/limit/recent