Being a gfx whore, my curiosity is killing me over gfx settings i cant seem to decipher!

First off, what does unchecking the "disable DoF" box do? It surely doesnt enable depth of field, i've never noticed it, and i cant notice any difference with it checked either..

Secondly, the Softness (adv lighting) setting which is supposed to control the bloom and such, has absolutely 0 effect as far as i can see.
Then i installed the postfx mod which basically replaced the bloom with a sharpen filter, and then the slider had a visible effect, so i know the options slider isnt bugged. Just that i cant possibly see any difference no matter how eagleeyed i am!
The only POSSIBLE impact i can imagine, is that the slow random "clouds" floating in front of the camera may be a bit brighter? Which cant easily be captured on screenies or reproduced. Is that it?

Here, you try! Feel free to save / open the images in seperate tabs and flip through. Screenshots of the slider at 0, 50 and 100.