Sony FX6 B4 developments

For those of you who may be interested in using a B4 lens on an FX6 or FX9.

A colleague of mine borrowed my Sony SEL20TC. For those not familiar, it's Sony's 2 x teleconverter which can be used with Sony's A7 series cameras and a number of Sony's longer lenses, starting with their 70-200 mm.

On returning it, he asked me, "Have you tried it on the FX6?" "No." I replied. Which got me to thinking. Be it madness or not. But being an old 2/3" shooter, I've always the hankering for the flexibility and range in one lens that a B4 servo zoom can offer. What does a B4 lens offer? It can offer a cheap solution to fill the need for a long range parfocal constant aperture lens. I've played around with adapting a B4 to an FS7, FX9 and now an FX6 before. So the two of us decided to chase this Unicorn. This is an experiment down that path.

NOTE! To be able to fit the Sony SEL20TC to the back of MTF's S16 B4 to E-Mount adapter meant, after careful measurements and calculations, I had to shim the rear flange of the MTF unit with a 0.7 mm shim. This prevents the protruding front element of the SEL20TC from meeting the rear element of the MTF S16 adapter. This still leaves sufficient back focus adjustment on the B4 lens. Though, the adjuster ends up about 50% through its adjustment in an anti-clockwise direction.