Trying to Determine what lens to purchase for 7D

[Adam Chesbrough]

I have the 50MM 1.4, 24-70 2.8, and 16mm fisheye 2.8 (which gives you some really cool effects). I have been dissatisfied with shooting video with the 24-70, think its because of the lack of IS and that I do a ton of low light at high ISO’s (i encode in prores LT rather than pro res, anyone think that should effect the quality?)

What is the highest iso that you guys go when shooting video, my video seems very grainy compared to others that I see online and I imagine that it is because of the high ISO.

What have people found to be the best wide angle prime lens? I owned a sigma 10-20 with my nikon D90 and it gave me some great stuff, doubt that would work for video though, would rather get some super fast prime lenses.Look forward to hearing everyone’s opinions. Thanks

macbook pro 17″ i7, 8GB RAM
esata external HD 7200RPM
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canon 5D mark II, 24-70mm, 50mm, 15mm fisheye, juicedink DT454, zacuto striker