Periodicals/magazines/blogs for cinematography?
For basics in digital cinema the Vimeo School is a great start.

There are tons of blogs for cinematography.

One of the most interesting blogs that covers gear and on the set experiences
is by noted DP, Philip Bloom, a real major force in modern digital cinema:
http://philipbloom.net/blog/

Coen Brothers too:
http://thecoenbrothers.blogspot.com/?zx=2bb8d66a241d6286

For me the best way to find what's up is to see if your favorite
director, studio, camera manufacturer, or whatever has a blog via Google.