Blurryeyed Loc: NC Mountains.

Apparently these lenses are pretty popular here on the forum, I would consider trading mine for other Canon equipment that I might find more interesting.... I don't get out much to do birding, I will say though this is the best lens I own, so whatever the trade would be it would have to be really interesting.

imagemeister Loc: mid east Florida

It is not a big difference. Operator techniques makes a much bigger diference.

RRS Loc: Not sure

It's a trade-off and I think you came out on the better end of the stick. If you shoot free hand and in early or late light then the IS is to your advantage. Like imagemeister said, the photographer makes the difference.

Swamp Gator Loc: Coastal South Carolina

I don't use IS for BIF or other wildlife action as it actually interferes with focusing, so I keep the IS off.
I only use IS for slow shutter speed hand held situations.
Plus with action situations I'm generally using a fast shutter speed anyway so IS is not really required.

Basil Loc: New Mexico

The new IS on the 300 has two positions. One for relatively stationary subjects and a second position for panning. Would that make a difference?

RRS Loc: Not sure

As long as you are shooting at a fast shutter speed, 1/500 and up you don't need IS. I usually shoot my BIF at 1/2000 or faster depending on the light. I do use the IS for low light hand held shots of owls and there is a time and place for IS. Just do what is good for you and remember to have fun too!

Carolina Wings Loc: Flew from North Carolina to Pennsylvania

Thanks imagemeister...it's just that it probably would've saved me a little money...especially since I don't use IS on my BIF photos:-(

Carolina Wings Loc: Flew from North Carolina to Pennsylvania

Lol...all my shots are handheld...I just can't stand being tied down to a tripod ;-) I sometimes feel like I could kick myself for not getting the 400mm 5.6...especially when I found out I didn't really need the IS!

Swamp Gator Loc: Coastal South Carolina

I did some fairly extensive testing of the 400 5.6 because I was interested in getting one.
My experience was the 300 f4 with the 1.4 had better IQ and still had fast AF.
I also like the closer minimum focus distance of the 300.
Plus you can't really use an extender with the 400 and the IS is still nice to have for those situations that require it.

I just wish Canon made a new regular lighter weight 400 f4 (not the DO) because that would be a sweet lens by itself and if it got super fast AF with a 1.4 that would be really nice.
Of course I would want it to be reasonably as well. :)

Oh and I do often bring along a tripod. But I use it mostly as a place to rest the camera when I'm not using it since I also shoot all action such as BIF hand held.
But the tripod did come in handy yesterday when shooting that eagle series I posted on the blog today. My arms would get really tired holding up the camera waiting for the eagle to jump off.
The last flight shot that I posted here was hand held though. I flip the quick release lever and zip the camera right off the tripod to capture the flights.

Carolina Wings Loc: Flew from North Carolina to Pennsylvania

Well, that makes me feel better Phil...because I really do love my 300! I haven't been doing flight shots for that long...but I certainly admire yours...and value your opinion!

Basil Loc: New Mexico

Well, I just made another GAS purchase to go along with the 300mm f4 L IS I just bought. This time, I bought a used Canon 1.4 II extender. Ended up getting it on EBay for $230. Hope that's a good price. Ad said in Excellent condition - but we all know that could mean anything.

imagemeister Loc: mid east Florida

That is about the going price ....