I was wondering if anybody has used one, i'm using a Olympus E-330 and was looking to buy the 2 x doubler to use on either of my lenses 14-45 and 40-150, i've read they can cause focusing issues, any advice would be great. I use the 40-150 to take alot of Rugby shots, my son plays and i thought this would be a cheaper alt than a new tele lens? Thanks