D300 does IR

I was out shooting today for the first time with an IR filter. As I got back I noticed that the photos weren't that sharp. I still have my old D70s hanging around and I'll try that the next time I'm out.

Do you think it (the D70s) could produce sharper shots because of its lighter IR rejection?

Anyways, here's one of the results. Prints available here:
http://www.redbubble.com/people/npmonkko/works/9216408-a-field-in-the-forest

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http://www.redbubble.com/people/npmonkko
http://nikomonkkonen.carbonmade.com