Here is a question. When purchasing a filter system do you go by 'apparent lens length' or acutual lens length. What I mean is the cokin filter set has 2 series A and P. A is for telephoto and normal stuff. It doesn't work at angles less then around 35mm since you start to get vinetting with the filter. The P series on the other hand is for wide angle shots since they are a much bigger filter. But my question is will I need to go to the P series when I get a digital camera due to the 17mm wide angle lens? Or is this counter balanced with the 1.5x magnification? In other words if my 'equivilent' length is 35mm am I still good with the A series?