Pentax also sold one for the 645 camera series, and likely for the 67 as well. Of course, as time went on the finder window changed so the right angle finder became more specific. Something about making some money off the accessories.
Right.
I have a 645n kit and, since I like close up and macro work, a set of tubes and the excellent 120 macro lens. Since I don't really care to lie down for little critters or small low lying flowers, I bought the 645 right angle finder. Unlike the angle finders for the K cameras, the 645 finder attaches with a rather fine pitch thread. Every time I use it I worry about cross-threading the darn thing, which could be an expensive repair! What was Pentax thinking????
Making money on accessories: I have the AF 400 handle flash, TTL with the LX and the 645. Versatile, powerful, 102 watt seconds, wonderful results. I also have the 6 C cell external pack, which furnishes high voltage to the flash, and gives really fast recycle and far more flashes than the 6 AA cells in the handle module. Of course this flash won't work TTL on my digital K 10 or K 5, although using its sensor gives good results.
The AF 540FGZ which WOULD work on my DSLRs, if I owned it, takes a 6 C cell external pack, which I understand furnishes the same HV as does the one for the AF 400, but the plugs connecting to the flashes are different! Sooooo....if I buy the AF 540FGZ I could buy its TR Power Pack III for $140, or butcher the connector on my AF 400 Power Pack, or kludge some sort of adapter. Grrrrrr......
While I'm griping, the first Pentax DSLR accomplished flash TTL by reading off the sensor, just as film camera TTL flashes read off the film. Then they changed to the PTTL, with a pre-flash. Did Canon and Nikon do similar things? What was the problem with reading off the sensor? My LX and 645n with TTL flash off the film, gave and give excellent flash performance. As does my Olympus OM 4 with its dedicated flash units with TTL.
Sorry for the grousing. I've been working on taxes......