Bahtinov Focus Tools for DSLRs
Autofocus doesn't work at night for astrophotography
Manually focusing at night can be a challenge, and autofocus doesn't work quite the same in the dark. Turn the autofocus off, the live view screen on, and slap on a BAHTINOV mask in front of the lens. You're ready to focus like a pro!
Developed in 2005 by the Russian amateur astronomer Pavel Bahtinov, the bahtinov focus mask works by diffracting incoming light into a predictable and recognizable pattern which you can then use as a guide to perfect infinity focus. With the mask attached, you'll be able to focus to infinity within seconds, saving you set-up time for nighttime photography. Click here to learn how to use a bahtinov tool