1.8

 I've begun to shoot increasingly in f/1.8. I've always shied away from using it extensively because 1) the DOF is so narrow it's hit-and-miss as far as getting the subject in focus, and 2) even when it is in focus you lose some sharpness. Yet, I can't help to enjoy its ability to really isolate your subject and produce some really nice effects. The bokeh on my 50mm 1.8 is not very desirable (only a 5-bladed aperture), but it also produces some nice vignetting at really high f-stops.