If you use the right camera focal length, things should be in scale and not blurry.  However, some IBL maps seem to work better than others.  Try a few combinations and see.  I think I usually get good results with neutral to wideish angle "lenses", starting at 50mm.

 

Quote - Another question regarding ibl maps. I dont quite understand to what purpouse they serve? Quite often they are out of scale and blurry are they suppose to create a poor man's DOF effet?