From the Canon Digital Learning Center:
So far in our eclipse series we’ve discussed camera bodies and lenses that can be used to photograph the upcoming total solar eclipse. This article covers solar filters, the most important consideration for solar photography and direct viewing of the solar eclipse.See the entire article on the Canon Digital Learning Center.
It is never safe to look at the sun without proper eye protection when any part of it is visible behind the moon!
This also includes not looking through your camera’s viewfinder when photographing the eclipse – use a solar filter on the front of the lens, and look through your LCD screen instead of the viewfinder!