What is the optimum viewing distance for the KMQ prism viewer?

The mirror based over/under 3-D viewers can be manually adjusted to fit most viewing distances.
With the prism viewer KMQ SSG1b, its fixed optical spreading of left/right eyesights (19deg) means that you have to measure the vertical distance of the stereo pair and then multiply by 4.5 to get the optimum viewing distance (paper or screen to viewer).

KMQ viewer is available in the USA again

Good news for the project ! One of the best known US web shops for stereoscopic tools http://www.berezin.com now also lists the SSG1b KMQ viewer - the main building block for the openKMQ project. This means, US artists, students and S3D-Photographers don't have to worry about international shipping and import taxes.
I very much hope, Steve Berezin also joins in as a provider for the platic kit components. The more requests he gets, the better ;-)