Hi Martijn,
Martijn Stol wrote:
> Most contacts are just passed through. The three extra contacts on the lens
> side are simply wired together. One of the other contacts is passed through
> the switch in the lens mount. If no lens is mounted, the circuit is
> interrupted. If a lens is mounted, the signal is passed straight through.
> Funny thing about that switch, though. The canon 1.4x TC has one, the
> soligor 2x TC has one, my eos 50e camera has one, but my eos 30 camera
> doesn't! I wonder what's it for... If your looking for the switch, it's at
> the 10 o'clock position when your looking at the lens mount... (or not).
>
Right under the front metal "wing" where the lens bayonet fits??
I found (in my 50E at least) that this switch tells the camera that it should
expect signal from a lens.
When there's no lens, and the switch is not passed, the camera works normally:
you can operate and the shutter will work. (you can see the mirror working and
the shutter opening if the time is long enough)
When the switch is triggered but no lens is present (like when you use an
extension tube, but no lens on it) the camera will meter, but when you try to
shoot, the mirror will lock up and the display will start blinking. You have to
turn the camera 'off' to take it back to normal.
Guess what you have to do if you want to use extension tubes with a pinhole...
;-)
Greetings,
Gerard.
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