hi all i have problem:
when compositing scene with vraycam+vraysun+vraysky before texturing all looking beautifully (all in grey colors-deffault material) when i placing materials - materials looking as OVEREXPOSE!
i change this parameters - vraysun+vraysky - mult…irr+light … but result is not good
10x in advance
Maybe your materials are too bright.
Using the vray real camera you have to use dark materials too.
Give a look to
http://www.chaosgroup.com/forum/phpBB2/viewtopic.php?t=16499&highlight=autoexposure
You should post your renderings and also Screenshots of your settings and materials…
this way the problem seems not clear
Tom
http://www.chaosgroup.com/forum/phpBB2/viewtopic.php?t=16499
and
http://www.chaosgroup.com/forum/phpBB2/viewtopic.php?t=16553
The first post deals with the physical material actual brightness BEFORE lighting, while the second has a link to a physcam auto-exposure script i prepared.
Hope it helps.
Lele
10x for scripts … i will be tested now 
here is a scene with standart camera + direct light 