Haven't had a coyoteget spooked by a flash yet but I'm sure it happens. I get lots of coyote pics over coyote trails, just have to scout for them.

Another idea is to use the trapping method of a dirt hole set-up. Just dig a small hole with some sort of backing and put some type of bait down the hole. Then spray the backing (post, rock, tree etc.) with coyote, bobcat or fox urine. Again a good idea to place this up wind of a know coyote trail. A link with diagrams
www.trapperman.com/trapperman/dirthole_set.html