Hi, Just a quick question. I have a Nikon 18-200VR F3.5-5.6 lense Although this lense is great as all rounder, I want to have a deciated lense for indoor photography e.g. children birthday party, and to get faster shutter speeds to avoid motion blur. Most shots i have taken so far between 20mm and 50mm seem to average around F4.5 I was thinking about getting a Tamron 17-50mm F2.8. 1) Would a F2.8 lense give a faster shutter speed? 2) or have I got my camera setup wrong? Setup of the camera is Shutter Priority, Auto ISO. Thanks.