I just submit a single photo and simple explanation of the photo to the editor. They would judge the photo and idea, then if they want it, I send them the article on cd, to the format of the magazine. There is a photo limit, the one Eugene is in, I have done too, and it is I believe a 30 photo limit. Each photo requires a caption which also references the article, so it's like you wrote the article twice, once in long form and then in short form like a picture book. Be sure and include a bit about you and your inspiration for the project. Don't go through all the work of writing the article and compiling all the photo's without being accepted first. The photo's need to be large and fine quality, like 7mpx or better. Your project is going to need to be very unique for most magazines, because they see a lot more duplicate idea's than new ideas. Eventually, you know all the right people, they know what you do and how you do it..then just pick up the phone.."dude..got this cool idea, what ya think!" and your cheque is in the mail! Oh..watch those sister companies too, like woodturning design is a conglomerate of a few other magazines as well. I heard my woodturning design article might have been stolen by their scrolling partner, but haven't had that confirmed for sure. Fortunately I have them on a pitch for another article anyhow! Mags a Mag too, so if they steal you off into a different mag, pays all the same.
Sometimes confirmation is same day, sometimes it's a month! Remember, if you get in, your article may not hit the press for many months, possibly over a year! They tend to be at least a couple magazines in the future, with several issues after that partially completed. The next issue where you can fit by your topic might be 10 issues from now, or might be 2 issues from now.