Skate Boarder at Night Fall

I was experimenting with my 5D and 24-70mm lens at a local skate park in the late afternoon until dark. These are not perfect but I thought I would show them anyway. Besides being slightly blurred, grainy, dark, and some blown white areas, the comp came out like I wanted. I did run them through Noise Ninja which helped a bit.

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I really like the second one, the sky looks menacing behind the skater

both the skaters are really dark, do you have an onboard flash with you? or better yet, an off camera flash? also keep this question in mind when shooting skating, "Can you see where he's coming from? Can you see where he's landing?", number one is fine for that, but for number two, it's as if he's going to land in a never-ending-sky, get it?

Thanks for the comments.

I shot with my 5D that night which doesn't have the pop up flash, but I do have a 580 flash I can put on it next time. I see what you mean about the coming and going of the skater. I don't think my son will mind going back and doing his jumps for me again