New to the board - thanks for any help. I am currently using a Nikon D50 with Nikkor 18-135mm f3.5-5.6 lens to shoot youth baseball, soccer and swim meets. All outside, during the day and dusk. Love the lens, but it won't quite reach across the infield, or to the end of the pool.

I am considering several options - (1) using a Kenko 1.5x teleconverter on my current lens ... have tried this with mixed results ... in overcast conditions, it is really slow ... otherwise the autofocus jumps like crazy, or won't work at all if the zoom is maxed out. (2) Purchasing a Sigma 28-300mm f3.5-5.6 lens, or (3) purchasing a 70-200mm f2.8 lens.

I'm not wed to these options. I can use a tripod or monopod. My budget is $300-$1000. Thanks for your suggestions.