I don't have my Retinas nearby, but as I recall, the IIc/IIIc (small c) have better contrast than the IIa. Keep in mind that most Retinas will need to be cleaned and serviced, which includes the viewfinder components.
The Big C models - IB, IIC and IIIC - all have the best viewfinders and include framelines for the auxiliary lens (not the IB, which has a fixed Xenar).
If you're looking for a better viewfinder, look at one of the Big C models.
Sorry about the deleted posts below. I was trying to make some edits while using a tablet device.
Last edited by elekm; 02-12-2012 at 10:12 PM. Click to view previous post history.