Since the gridlines on my NEX-5 are rectangular, and there is no 1:1 ratio option in the camera, I simply took a couple of thin strips of semi-transparent, removable stickers and placed them directly on top of my LCD for framing. Works like a charm, since there isn't a viewfinder to deal with. With my A900, even though I had a grid focus screen with a square in it, I actually removed the focus screen and placed a couple of pieces of black tape to square of the VF, and I just used center weighted metering. Worked surprisingly well, since the A900's focus screens are so easy to change.