I have done some minimal testing. Most of the time I cannot tell a difference for the short conceptual / music video type web output work I am doing.
My expereince is that if I have a shoot where I had literally no light and tons of noise- eg a single lamp at night at 28k+ ISO and the image is falling apart- then when I go to HQ at high res- then compress to 720p or 1080p, the noise and grain appear a bit better than the lower quality codecs.
For nearly everything else I cannot tell a difference for my own purposes- but if theatrical / big screen projection are your goals as a final desitnation- it may very well be a different story and workflow. So please reach out to others who are working for that level.
Phillip Bloom has a nice post about how he handled some of this (before Premiere was better handling the 1DC) here-
go most of the way down when you read his post- it is a terrific and helpful about how he did the video as well as some basic workflow-
(in the question section #20 from me is where I ask a newbie question about output - haha)
hope this helps!
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