I know I must be overlooking something somewhere, but here is a question I was discussing with a friend of mine. Suppose we agree that the major reason for the invention of the slr was the mirror and the ability to look/meter through the lens, and the ability to change lenses (although some rangefinder can do that). If this is true, then now there should be no problem to see through the lens because once the image hits the sensor, it can be (electronically) transferred to the lcd screen (or wherever else you want, viewfinder etc...). We could use interchangeable lenses withouot any mirrors or curtains but just the old round shutter (the James Bond one, I forget its name) and thus have lighter hardware and more quiet operation etc... So why are dslr still superior?