After Perseides Shower yesterday night I definitely decided to go 5D3 within the next weeks. I applied 600 rule with my current 30D and a Canon 10-22, which yields exposure values between 25 to 30 seconds. Shot at ISO 800 as highest. Small crescent moon. What is your highest ISO setting while taking nightsky photographs of e.g. Milky Way? ISO 3200 or even higher? Thanks for any help!