I've been using a simple dime-store magnifying glass to focus with for three years. I started out with a loupe, but already had a spotmeter and framing card dangling from my neck and so I used to put the thing in my pocket, where it was too bulky and picked up difficult to clean crud. The magnifying glass works just fine -- and even better in some ways because I can angle it in the corners like a Silvestri loupe. Do I look unprofessional under the darkcloth without a loupe? You BET! ...but who cares, it's DARK under there! Anyway, I keep it, a pocket level, and a pen light in my one back pocket all the time and can always tell which I'm pulling out by its shape.