TTV or “Through The Viewfinder” is kind of a neat idea, though the results are sometimes very primitive looking. The idea is that you take a photo (usually digital) through the viewfinder of another, older (usually film) camera. Most folks shoot through TLR (Twin Lens Reflex) cameras, which have a large, waist level viewfinder which one can shoot through it with a standard 50mm lens or even a zoom lens. Others experiment with everything from old range finders to box cameras, and even toy cameras. Some cheaper versions of the waist level TLR cameras can be had for a few dollars on ebay. Since the functionality of the camera really doesn’t matter (you are only using the viewfinder), as long as the view piece is crack, mold, or fog free, the camera can be otherwise broken and still serve it’s purpose for you. Some folks even desire the dusty cracked, or fogged viewfinders for some added grittiness.
I, on the other hand, don’t currently own a TLR or any other camera worthy of this project (yet?), so I actually used some template layers that other folks have made with their TTV cameras and simply worked them into my photos. I cheated, yes, but I had fun at it, and may consider picking up an old Kodak Duaflex sometime soon to give the real-deal a go.