Canon EF Lens Controls

[lost]

Does anyone have any info relating to how a Body communicates with the Lens?
Specifically how the body tells the lens to change aperatures? Maybe even a pinout diagram and details of the communications.

Thanks I am going to attempt something rather out of the ordinary, but dont want to talk too much about it until its done.


Edit: I have an email into Canon for this info. Lets see if they will be helpful.

[accord]

You can try here: http://home19.inet.tele.dk/ne/manualer.htm

Good luck.

[blue_max]

Does anyone have any info relating to how a Body communicates with the Lens?
Specifically how the body tells the lens to change aperatures? Maybe even a pinout diagram and details of the communications.

Thanks I am going to attempt something rather out of the ordinary, but dont want to talk too much about it until its done.

You can't leave us like that!!! You have got me wondering now.

Graham

[lost]

No luck there, I am looking for signal or voltages sent to and from the Lens to change the aperature.

Thanks for the link though.

[FlyingPete]

Ah no one really knows except Canon, even the likes of Sigma and Tamron have to reverse engineer the comunications, hence why for reasons unknown these third party lenses often don't work with the newest cameras.

Same goes for flash guns and their communications with the camera.

[FScott]

This may be quite an involved process. I doubt it is as simple as applying a DC voltage to the correct pin. I would guess that the pins are some kind of serial bus to talk to the embedded processor in the lens plus several power and return pins. I also doubt that Canon is going to tell anyone since this would help the 3rd party lens companies. Your best bet is to build a breakout adapter that fits between the camera and the lens perhaps by taking apart a cheap teleconverter (tamron 1.4x) and probing for which pins are DC power and putting the rest on a logic analyzer. Good luck!

-- Scott.

[FlyingPete]

This may be quite an involved process. I doubt it is as simple as applying a DC voltage to the correct pin. I would guess that the pins are some kind of serial bus to talk to the embedded processor in the lens plus several power and return pins. I also doubt that Canon is going to tell anyone since this would help the 3rd party lens companies. Your best bet is to build a breakout adapter that fits between the camera and the lens perhaps by taking apart a cheap teleconverter (tamron 1.4x) and probing for which pins are DC power and putting the rest on a logic analyzer. Good luck!


There will also be some two way stuff happening, the lens lets the camera know a bit about itself as well, focal length aperture options etc. Newer lenses also report distance to focused subject.

I would imagine it is a fairly typical tired and true serial protocol with some very proprietory information.

[lost]

Yes, I know this may be an exercise in futility. :) But that is part of the fun. I am only conscerned with the Aperature right now. But that will probably be just as hard as the rest.

[CyberDyneSystems]

....something to do with t-cons...?

[xuxu1]

....something to do with t-cons...?
....something to do with t-cons... and AF ???