Join Date: Mar 2007
Location: Birmingham, West Midlands, UK
Programs: Mucci, BMI*G, M&M SEN, FB Gold, PC Plat, Father of GhettoIFE
Posts: 3,972
I've been a no filter person for a long time... anything that blocks light from getting to the sensor/film is not a good thing. Flare and ghosting are just additional side effects.
I only run one UV (Kenkro) on my 17-40L, just to protect the front element, but more often than not, it comes off (although it adds a degree of weatherproofing a good lens)