Hi Everyone

I need a little bit of help as I havent used a a 1.4 before- i currently own the 1.8 and find that i use it quite a lot. It's nice and light, pretty sharp and great in low light conditions. However, i've been doing a lot of movement photography at the moment and found that the AF on Al Servo just cant keep up with my subjects- dogs mostly, and i'll get 1 out of 3 photos with the eyes nice and sharp, which is a little disappointing- especially when i know what this little lens can do.

For those of you that have perhaps used both, or have the 1.4 canon, would the AF be that much quicker than the 1.8's to lock onto a subject? I've found it for sale online for about $250 so it's very affordable.

Thanks very much in advance

Cheers