Just picked up a new 70D and moving down from a professional 1D body. Don't call me crazy. I've been doing a ton more video work and servo focus on the 70D sold me on it. That plus I am pocketing almost $2000 to put towards new glass. Yes, coming down from a 1D MKIV, the 70D does feel light, and the thing I miss the most of the large bright viewfinder. So far I haven't noticed much of a difference in IQ or dynamic range but I haven't pushed the 70D into any difficult situations yet.
Below is image # 1 from the 70D ( I didn't even rename the file) - This is my friends daughter. So far so good !


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