The Letus Elite has two items the Extreme does not have: (1) Backfocus ring (2) upgraded achromat lens. The latter is supposed to improve image sharpness. Great! Now could somebody explain to me what an achromat lens is?
An achromat allows the camera to focus closely on the GG since the GG to lens distance is often so close. A poor achromat can introduce unwanted artifacts like chromatic abberation and poor edge to edge sharpness.
