ok so i have a 1500 budget and i want to buy either a 50d without battery grip with a 70-200 f4 or a used mark II wit h70-200 f4. I am looking for their to be better quality in the noise especially without a wider aaperture that f4. as an alternative i could get a sigma 50-150 2.8 instead of the f4. I am venturing my way ino sports more but also want to do everything ALL AROUND but i NEED better noise up to 800 how will it handle on both cameras. also how is the sigma lens. Thanks I am upgrading from a XT.