A broody hen gets off the nest at least once a day, sometimes for almost an hour, so it wont hurt to take your time when candling. Better to be careful and not drop one! I use slide projectors for my candlers. If you cant see into an egg with one of those, it cannot be done.
You can get a really good flash light at WalMart for about $20. Make sure it has a spot light feature which really projects into the eggs, and you can see EVERYTHING so good...I love my little flashlight.
I just took an extra heat lamp I have, replaced the bulb with a normal 60 watt, then taped a piece of cardboard with a hole in it over the dome. it works great, and the best part is that if you point it upwards, you can have hands free viewing by just placing the egg over the hole!