I am a beginner and wondering if one of these 2 additional lenses would be worthwhile for me to spend my money on. Here is what i have Nikon D80 18-135 mm f/3.5-5.6G I was looking at the 50mm f/1.8D and the Zoom telephoto 70-300mm F4-5.6 both are in my $$ range ($100-140). Can someone give me an overview of the pros and cons of these 2 types of lenses? Or if what i have now will suffice? I do know that the lens i currently have does not allow enough light in for some of the fast shots i have tried to take of splashes in water, and i thought the 50/1.8 might help with that. Any suggestions?