Creating a HDR - default 'brightness' in my material slot

[tricky]

I am having a bit of an experiment with creating a HDR image from multiple bracketed photos. Once I generate the HDR and put it into a vrayHDR map slot, the preview is very dark, which means I need to up the multiplier of the vraydomelight to which it is assigned quite a lot - around about 100 or so.

When I use a Peter Guthrie HDR, the HDR is already quite bright (you might say 'normal') in the vrayHDR map slot. This means I only need to have the vraydomelight with a multiplier of around 1.0

Why is this? Do I need to tweek the default brightness of the HDR somehow?

[joconnell]

Yep you need to set the default exposure, normally in something like HDRshop or wherever the hdr was made.

[Neilg]

you can do this in photoshop too. open one of guthries, add an exposure adjustment and see how far you have to push it to get it looking like yours - do the opposite to yours and save it.