The easiest way to get TTL metering on a Twin Lens Reflex (TLR)  Rolleiflex is of course to buy a new one, but let's say you love your old 2.8F and want to do things a different way?    Well here's how you can do this in two steps....

Just posted a big table of all the different corrective diopters available for all the different Rolleiflex cameras including - TLR's, 6000 series, and Hy6.  Covers waist level magnifiers, 45 and 90 degree prisms.  

Click on the link to see the post...