Camera settings readout through flash cord

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Camera settings readout through flash cord

Post by st_m »

I have a question:
When I set my SB800 flash on any camera, I can read the settings (ISO, focal length of the lens according to which it automatically zooms its own reflector, aperture and (calculated) maximum subject distance) in the display of the flash. These data have to be transferred from the camera to the flash unit.
Does anyone know, how this exactly works? I know there are some more contacts than the central (fire) pin, but I have no clue, which bus system or data format they use for communication between camera and flash.
I would also like to know, how the preflash system is exactly working. Already had a look at the light output with an oscilloscope connected to a photo diode, and can see the preflash pulses.
Does anyone have detailled knowledge about the hard- and software involved? I ask this question, because I want to build a microscope light, that is controlled by the camera's flash shoe (and not only through the fire pin, but also can evaluate the other information and use something like the preflashes in normal photography to examine exposure conditions directly through the microscope).
I would like to use a microcontroller in my circuit to do all the hard work.
Thanks very much for any suggestions.

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Post by MikeBinOKlahoma »

I would go investigate the website They know things about the dark side over there! :-)
Mike Broderick
"I must obey the inscrutable exhortations of my soul.....My mandate includes weird bugs."--Calvin

(reposts on this site of my images for critique or instruction are welcome)