There are many threads here on this topic.
In my personal experience, the dirt-cheap Wagner "Control Spray" has exceeded my wildest expectations for quality and reliability. It's the one with the turbine built right into the handle, about $70 at Home D. etc. It sprays undiluted Clearshield Canvas Type C Gloss like a champ. Just keep the volume cranked way back and figure on 2 or 3 coats total with some drying time in between. Practice on some thick cardboard until you get a feel for the right, sparing volume. Cleaning is important, and make sure you don't get any dirt or dried-up paint skin particles in the soup.
Beats the heck out of rolling! Don't know how many canvases I destroyed with rolling, but I'm getting close to 100% successes with the Wagner.
After just a few canvases you'll be able to repeatably get a finish pretty much anywhere you want between satin and gloss. If you aren't slopping on too much at once, 2 coats gives a nice satin, 3 starts to become glossy. Each coat should be one thin pass in direction, followed immediately by another pass at 90 degrees. That takes me about 90 seconds on a 2 x 5 foot canvas. Don't release the trigger between swipes, and do the turn-around spraying into space, not on the canvas. Initially give the gun a few seconds to start picking up paint. I have also used a very expensive HVLP gun with an external turbine, I prefer the Wagner because it's less hassle on cleanup and because the whole darned thing stores compactly on a shelf. Got about 30 large canvases finished this way, the Wag is still going strong. Gotta love it.
