Hi - wondering if anyone has had any experience with this pentaprism diagonal from Kasai Trading:
Kasai Pentaprism
Here's a "better" explanation/translation:
Widescreen - Kasai diagonal
It is stated to have 97% reflectivity which seems rather good for such an arrangement, and with all the benefits of a correct view. However, it only seems to come in 1.25" and has a longish light path (around a 2" mirror diagonal, but that's ok), and is not cheap! Sounds interesting, though.
Andrew