I need a lens with the following requirements for documenting dance performances with 60D and ML:

1. constant aperture
2. good zoom range (like 18-70 or better)
3. smooth focus ring
4. fast if possible (2.8 or better)

Is there a manual lens (cheap) like this? If not, any Canon lenses?

Thanks in advance...

How close will you be to the action? I assume you're gonna want something capable of both WIDE and MEDIUM/CLOSE-UP? Lenses with 2.8 aperture or faster will cost you, especially if they cover a wide array of focal lengths; you might want to look at some non-Canon brands (Sigma, Tamron, Tokina). Any faster, and you'll likely be looking at prime lenses, which won't do you any good unless you have multiple cameras.

Canon (and non-Canon brands) have inexpensive lenses that cover an array of focal lengths (18-135mm comes to mind), however you sacrifice f-stops (f3.5 max, a lot of the time). If you're shooting indoors in low-light conditions or outside at night, you might have issues.

Sorry, not being much help. Do a search online for the non-Canon brands and see what you can find. You're likely looking at a $400-$600 range.

it's either Canon 17-55mm f2.8, 24-70mm f 2,8 or Tamron 28-105mm f 2,8, zooms faster than f:2.8 cost a bit more :)

Maybe a 24-70 f/2.8 is what you are looking for? There is a Canon L version as well as a Sigma version. The Canon version is one of the most popular lenses and one which pretty much every working photographer owns (along with the 70-200), but the Sigma version is available for half the price.

When engineering lenses for DSLR's there are a few general limitations:

1. f/2.8 is the fastest aperture you'll find in a zoom lens
2. An f/2.8 lens is generally limited to about a 3x zoom range (eg 17-50, 24-70, 70-200, 50-150, etc).

There are exceptions to these rules amongst cinema lenses, but in the DSLR world this is pretty much the limit without compromising either quality, size, or price.

Thanks for the replies. Do all the lenses mentioned have smooth focus and zoom rings? I will need to zoom in and out while recording.

What about vintage manual lenses from Nikon or others - much cheaper - (with adopter) that are of good quality and have qualities I'm looking for. Any suggestions?

I don't think any still photography lens has a sufficiently smooth ring to be able to rely upon it for consistantly smooth zooms. Part of the problem lies in the fact that the lenses do not zoom at a constant speed, even when the ring is turned at a constant speed. There are sudden parts where the zoom might speed up or slow down, so maintaining a steady hand and perfectly controlled rotation, it still won't zoom smoothly.

If I zoom mid-shot on my DSLR's I always edit out the zoom in post. If this is not possible for you, then I think DSLR's are probably not the right tool for the job.

1. f/2.8 is the fastest aperture you'll find in a zoom lens
for any DSLR. There are a couple of Olympus F/2 zooms for Micro Four Thirds cameras e.g. GH2. The 35-100mm (70-200mm full frame equivalent) & the 14-35mm (28-70mm full frame equivalent).