 Among the DSLRs that do manage to focus using the standard phase-detection sensors used by DSLRs, unlike some compact digital cameras none has managed to show 100% frame coverage.This removes one of the key advantages of live preview over optical viewfinders, especially on more budget cameras.Additionally, 100% coverage optical viewfinders have recently become more common and affordable with the appearance of the Canon EOS 7D, Nikon D300, Olympus E-3 and the Pentax K-7.