[Blue]

In addition to the O-ME 53 on the *istD and K20d, I have the m version of the Pentax angle finder which as 2 settings of 0 and 2x magnification. If I need more than the 1.18x (it sin't really 1.2x) of the O-ME 53, I go that route. However, they are a bit difficult to find on the used market.

Edit: I think Olympus had one that may work with our m and newer viewfinders but haven't verified fitment.