Since I just used this I'll give it some explaination.
You have to already have the tonemap controler in your map to start with and if you think the HDR isn't dynamic enough, or is too dynamic or is simply burning your retinas then here's what to do:
In your console turn on cheats (sv_cheats 1) and then use these three commands and simply tweak the value afterwards:
ent_fire tonemap_global SetAutoExposureMin .6
ent_fire tonemap_global SetAutoExposureMax 1
ent_fire tonemap_global SetBloomScale .3
Make sure you use the name of your tonemap controller entity in the place of tonemap_global.
Heres what each does:
SetAutoExposureMin sets the minimum level of light it will allow into your simulated eye, SetAutoExposureMax is the opposite, the maximum amount of light it will allow into your simulated eye, the further these two values are appart the more dynamic the range, so .9 and 1.1 respectively will be almost static, you'll never ever see it change, but .5 and 1.4 will have a very noticable change between light areas and dark areas.
The last one is what controls the thing called 'bloom' and using anything much over .5 for TF2 is a mistake. It will make all the normaly bright areas in the map have a surreal kind of glow, all the time. setting it to 0 will remove all glow totally, I find .3 ish is roughly right for TF2.
once you've found a set of values that work nicely scribble them down somewhere and return to hammer.
Find your logic_auto (or make one now) and set the following outputs:
onMapSpawn | Tonemap_global | SetAutoExposureMin <value>
onMapSpawn | Tonemap_global | SetAutoExposureMax <value>
onMapSpawn | Tonemap_global | SetBloomScale <value>
and you're done :thumbup1: