The view through the T is really unusable as a viewfinder. The openings- and thus the view- are the round, and the RF patch covers around 80% of it. It might corospond to a 250-300mm lens; even if you could find such a thing and wanted to use it, the shape is all wrong- you would only get a vague sense of the framing. You're much better off using seperate finders. I use my T mostly for my 21mm lens, where the finder is no problem. I can generally Zone or hyper-focus, and use the finder for framing, which makes it as fast to use as any other camera. The RF is there when I want or need precise focus. Even with longer lenses, I find the T is pretty fast and easy to use, and the long base and high magnification make for precise focusing. It's a great cheap back-up body.