I have an ex Govt
Davro Optical Systems electronic focus surveilance 4" or 5" lens system that would make a great scope for a cannon!

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Weighs about 20kg on its flat bed base and from memory has a std 35mm Nikon camera and an old style video camera mount adaptor.
I think it may be one of these with older large round multi-pin plugs:
ZOOM SYSTEMS
Available in 4", 5", 7", 8", and 12" clear apertures with zoom ranges of 400 mm thru 3000 mm, 125 mm thru 1250 mm, 530 mm thru 4000 mm, 500 mm thru 4000 mm and 820 mm thru 6400 mm focal lengths. |
All of these zoom lenses are electronically controlled and available with RS-422 serial communications and tell back of focus and zoom positions to obtain quantitative metric data. |
www.davrooptical.com