Quandary!

[greypoint]

Thanks for help and suggestions. Still undecided. Used the 100-300 this morning in fair to reasonable light but still needed highish ISO to achieve the sort of shutter speeds I felt I could happily hand hold at but I still think some shots suffered from camera shake to a degree. Best option, of course, would be to keep the 100-300 for good light or occasions where support is available and get a lighter lens for winter dog walks. As Chris says, using a lens which does everything internally and stays the same length throughout is very nice. Looks like the 70-300 IS can produce the goods though.....
Fortunately, I still like the camera!

[sassan]

Most of what you carry, most of the time, if around the waist, does give you a real comfort and extra mobility so think about something like this one if that fits your body and lens attached. Ref is just to give the idea (You don't want one with a tight inner compartment).

LINK - 1

When on hand, a hand strap is the best aid you may call for. Pros with giant size camera like 1D and larger fast lenses use these straps all the time. The problem with those strap is your 40D or for that matter any body without built in battery grip, lacks one of the point to secure the strap so you need one that uses the cameras under surface tripod screw. I got the Olympus version from ebay that are going at shamefully low price but the problem even after cutting that extra ridge that is for Oly's body alignment securing, it still has the problem of covering the battery compartment door so I have to remove it every time I need to change the battery(And gush that happens too often and mostly when you really don't want it). Here is one cheap and right one for your EOS that fits and doesn't have that problem:

LINK - 2

As for the lens you know my first advise is wait for when you are finantially ready to step into one of the 4 sister L lenses in 70-200mm range. The non IS f/4 version is about $500 and with the expect to arrive soon canon's fall rebate you may put hand on one. You and your 40D deserve a better glass for sure. Of course you can argue the lack of extra reach, but sharpness and color render is unequivocal by any other canon lens or for that matter any other lens in the world. I would go with Sigma 100-300 for now that is a quit a reasonable lens.
Sigma 70-300 APO DG macro is possibly the best budget lenses in the range you are talking about (No IS).

[greypoint]

Thanks Sassan. I did have a 70-200mm f4L when I had my 30D and agree it's a nice lens, but not quite long enough, and I had a 70-300 Sigma for my Nikons. Fortunately I bought the 100-300 at a very good price so if I decided to swap for the Canon 70-300 it should'nt involve any outlay.

[wolfie]

Pity the 200mm is not quite long enough Sue, as with this one http://www.dpreview.com/news/0710/canon/canon2002.jpg you could probably shoot birds in any light. Could be you would also have to take a body building course

[sassan]

A similar size and weight 300 F/2.8 is just an excellent choice if one can afford it.

[greypoint]

Well, job done - 70-300 bought and Sigma 100-300 sold. Very pleased so far. Lightweight, focussing not quite as fast but OK. Keeping IS in mode 2 to allow for panning seems to work well. Small crops of snatch shots - more successful than attempts with 100-300mm. When I get the cashback i'll be able to get one of those camera straps as recommended by Harry.

[miketoll]

Looks to be working well!

[sassan]

Congratulations.
Now you have one less excuse for Shakiness

[greypoint]

Just the usual one of old age now!

[wolfie]

In that case welcome to the club Sue