ProRes brighter than other codecs - not good

Recording Z5U output over HDMI to PIX220. For the record, I observed this same thing with Atomos Ninja. When I use ProRes HQ (or any flavor of ProRes) the file is considerably brighter than the brightness of DNxHD or HDV. In some cases the highlights are blown out where they are not in the other codecs.

Looking at it in Sony Vegas, but seeing the same thing in After Effects.

Any thoughts as to why?

Hi Gene ,
The guys at the BMC forum talk about this. Exposing for ProRes and RAW is different.
Basically you do the ETTR method, (expose to the right)
Set your zebras to 95 or 100 and expose so the highlights don't have the zebra.
It's explained more here in this thread.
http://bmcuser.com/showthread.php?7846-ETTR&highlight=Ettr

Thanks Jake! Will be helpful. Problem is I usually record to HDV and External recorder simultaneously - and this doesn't happen with DNxHD, although perversely ironic, my Windows system does not like DNxHD.... ultimately to my mind it makes no sense for a codec choice to change the overall brightness.

Useful info kk5hy - thanks.