Canon Prime Lens and remote focus

[Photosbykev]

Has anyone reverse engineered the focussing signals required to remotely focus the Canon EF mount lens ??

Obviously with a normal dSLR behind the lens the focus can be remotely controlled via the USB connection. If I wanted to mount a CCD behind a Canon lens I would lose this functionality but if the signals/power to control the lens focus could be replicated then the lens could still be remotely focussed via an adaptor ring.

An alternative would be to make a motorised belt drive that coupled to the focussing ring of the lens and control that with a stepper or DC drive

[jgs001]

There is an option, not belt drive, I've seen somewhere with a pair of rings that fit to the lens and give a fine tune drive mechanism of some sort (from memory) for focus, probably easier to remote control too.

[Psychobilly]

Sigma,Tamron et al....have reverse engineered it...

Dont know if theres any info in the public domain

Quick google....

http://photography-on-the.net/forum/archive/index.php/t-108016.html

The Signals are listed here...

http://f20c.com/stuff/canon/partslist/EXTENDER%20EF%201.4X.PDF

but no info on the "protocols" used...

The link doesnt work anymore

http://www.birger.com/Merchant2/merchant.mvc?Screen=ef232_softintf

Looks like its SPI but no more info found ... yet...

Billy...

[ollypenrice]

There is an option, not belt drive, I've seen somewhere with a pair of rings that fit to the lens and give a fine tune drive mechanism of some sort (from memory) for focus, probably easier to remote control too.

Telescope Service sell these.

Olly

[Psychobilly]

Think Dangerous Dave uses one... and I started to make one...

As shown in this thread....

http://stargazerslounge.com/imaging-deep-sky/110035-nan-ccd-pentax-6x7-new-project.html

Billy..

[Photosbykev]

Thank you for all the info, it's got me thinking

[Psychobilly]

EOS Lens protocol analyse - anybody intresting?

Still looking...

Billy...