Air Display, most suitable lens?

Hi,
As an aviation nut, who goes to lots of air displays, can someone tell me what would be the best lens to go for? I don't have limitless amounts of funds available, but I do have some. I currently have an EOS 10D, with a canon 100-300 lens (Not an expensive glass lens - not that I understand what that means anyhow!).
Can anybody point me in the right direction?

Many thanks

Dave

If you can afford the 100-400L IS then that would be my recommendation.
It is a good zoom range and a great quality lens.

There are a few people who use the sigma 50-500 which also has a good reputation and is cheaper.

Presuming you mean a display of aircraft flying (as opposed to static display of aircraft on ground)

The 100-400 IS seems to be the lens of choice for Canon users. I know it is mine. At a recent air show, all but one of the Canon users in the media platform were using 100-400 lenses, the exception was using a 400 prime.

The reason I prefer the 100-400 for air shows is that the push-pull design allows for very rapid zoom, which comes in handy when the planes are zooming past the spectators and photographers. It is much easier to pull in and then pull out, then twist right then twist left, especially since I would need to readjust my hand to get full range of zoom with the twist (maybe I hold it wrong).

Also, the extra range comes in handy over any of my other lenses.

I will admit I have not used the Sigma 50-500, although I did see one Noink user with one, but he wasn't very talkative.

BTW: if you meaning a static display, then just use the same lenses you would use for portraits.

If you can drop a wad of cash, the Sigma 120-300mm F2.8 EX is another good choice! I have shot mine at Farnborough and fairford Arishows in the UK last year and I was most impressed, especially at Farnborough when Cadwell and I met up and I borrowed a 1.4x from him for the day as he shot the 100-400L. I had a 420mm F4 lens vs the 400mm F5.6. It can make the difference, especially if you take the 1.4x tc off and you have a 300mm F2.8 lens! The good, the bad and ugly...good: I got is early on when it was $1900; bad, currently going for $2400; ugly, I don't see it going down but what do I know. About the only thing missing is a solid IS system, or OS for Sigma.

I'm impatiently waiting for the Paris Airshow (Le Bourget) which will begin in less than 2 weeks from now, and I'll go there with my 100-400 (and the 1.4 T-con, too)