30D won't focus w/o battery grip
I haven't had the problem (traded my 30D up to a 50D), but it sounds like the shutter switch might have a broken or marginal solder joint. Although I can't explain why it would work with the battery pack on. Is it be intermittent?
Can never hurt to have a spare battery, though.
|Child and seal by APenza|
from Kids world
|Calatrava in Reggio Emilia by NCV|
from Your City - Telelens in the City
|Aurora's, Science and the Milky Way by man4mopar|
from My Best Photo of the Week