It's not a video, but you get a good idea between different ISOs.
Canon 7D ISO versus noise test images Marvelsfilm’s Blog

I take it as gain on our video cams. (right,,,? no...?)

JJ

Tim,

All my thoughts are referring to video and I'm in the same boat as you, just a few weeks ahead building my arsenal of lenses.

I have the Tokina 11-16 and enjoy it very much. It is, however, too wide for everyday use. It's more of a specialty lens that you will use more than expected. Very nice, rugged, and great push/pull Auto-Manual Focus ring with fixed f2.8.

If you have some money and want to end the search: Consider the Canon EF-S 17-55 IS f2.8. It's $1,000, but has great optics, IS, and a fixed f2.8 and will go as wide as you need for normal circumstances and has enough reach to be fairly close at your 10-15 feet requirement. You could survive on that lens alone for what you describe. My 2nd lens choice would be the Tokina 11-16. A 3rd would be Canon 70-200mm L f2.8 IS (or f2.8 L non IS, or f4 L if I couldn't afford the 2.8). The Canon 50mm f1.8 lens is incredible for stills and video where you don't need to focus. Focus, however, is pretty rough and fixed 50mm will require you to work a good bit harder for shots. Amazing optics for $100 though.

If you are on a budget for shooting dynamic content: Consider the Tamron 17-50 f2.8 as your first lens. Add Tokina 11-16 as 2nd when you can.

If you are on a budget and want to shoot controlled environments; that opens up a lot of lower cost options in older manual SMC Takumar or Nikkor primes at very reasonable prices that have great focus and optics. You will, however, lose the ability to use AF to get initial focus, which is a very convenient feature.

I use 28mm f1.8 and loving it very much. yes, tough to get focus right, but with lots of practice, I got better at it. People do use Z-finder type aid for focus (i own one, too).
I am thinking about my next lens to be 70-200mm f2.8 IS. It's very pricey so I am waiting for the right moment. BnH is offering $150 off on that lens till 1/16/2011, so I want to buy before that.. or could go to local store and try out a couple different lenses.
This whole lens thing is very new to me, too, but I am learning a lot from this Forum and my talented colleagues.
I visit here a lot for DSLR lately and actually planning to attend the meeting next January as well.
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jj

F 2.8 gives me as shallow a depth of field as I need. Any shallower, and I would have trouble keeping moving actors in focus. It also provides a nice level of bokeh, (blurry background). (Actually F3.2 seems to be the sweet spot for the look I like)

You don't need much light to shoot the 7D at F2.8. I shot these pictures at ISO 1600, with 1/60 shutter speed in a room lit with two lamps, each with a single 40 watt blub. When I use 500 watt tungsen key light, I have been shooting 24P at ISO 200 with 1/50 shutter speed.

The two lens I use are the Tamron 17-50mm and Sigma 50-150mm. Here are pictures of the two lens each taken with the other. They cover everything I need for video and I got them together for under $900. I'm happy.