Recommended Lens for Olympics

The 100-400/4.5-5.6L IS USM would seem to be the obvious choice. Longer than that the lenses get very heavy, very expensive and very conspicuous. You don't want to be trying to hand hold a 500/4L for very long. The 400/4DO IS is smaller, but I think a zoom will be more useful.

If you don't mind 3rd party lenses, Sigma now have a stabilized 150-500mm F5-6.3 DG OS for around $1000 which might be interesting.

You may need to leave it at home, they are not allowing "pro" gear without press passes. There is a thread about it here somewhere.

hopefully, this link will work

http://photo.net/travel-photography-forum/00QE1g

You might want to do some research as to whether or not you'll be able to bring a 5D into the venue.

http://en.beijing2008.cn/spectators/n214263111.shtml

The 5th item under 'House Rule 2' might preclude bringing it in. The last item under Rule 4 regarding flash photography could affect you as well. As a real stretch a 5D might be considered to be 'professional recording equipment' referenced under Rule 5.

sorry the link wasn't 'live' but Richard's is better anyway; perhaps a point and shoot will have to do though the shutter lag is such a pain! cb :-)

Clearly you need on of these

But more seriously, sigma as have a new 120-400mm which may work for you, another thought is a canon 300mm f4 with teleconverter, now I don't think I've ever seen one, let alone used one but would that be any smaller than the other options?

Since you live in Beijing, at least you won't have your camera confiscated by customs when you fly into the country, as has been reliably reported is happening now. You get it back when you leave, but it's a hell of a way to welcome tourists.

Things don't look nice over there - (link)

Even Homeland Security hasn't stooped to that level yet. They just confiscate laptops and memory cards - http://news.yahoo.com/s/usnews/seizinglaptopsandcameraswithoutcause

I am not versed on the exact allowances if any, or not, for spectators to pass security.

I have been (as a spectator) to Previous Games.

From the Canon line up I would initially be looking at the 200F2.8L (or the 135F2L) and having the x1.4 and x2.0 converters in your pocket. If you choose the Canon converters use Black Tape around them. This would be a base as a general lightweight kit, IMO.

I STRONGLY suggest you are aware of the specific allowances to get you past security, and you then have a protocol to confirm those rights, should you initially be refused entry.

As you live in Beijing that will be a lot easier for you than others.

After having clearly identified what you can and can not do, if allowed: I suggest the 70 to 200F2.8LIS and the two converters I mentioned. My rationale for these choices is predicated on the necessary lens speed you will require, especially for any indoor events.

WW

"and you then have a protocol to confirm those rights"

Somehow I doubt that you'll really be able to insist on your "rights" over there.