Camera Shutter speed sensor

Benoit

For my first project using a microcontroller, I was thinking of building a camera shutter speed meter/sensor.

I've got a small collection of old cameras, and I enjoy taking black and white photographs with them. My main challenge is that these old cameras often have slow or sticky shutters. If I could measure the actual speed of the shutters, it would simplify my life in the dark room.

I have bought the Basic stamp sampler ( one of each of the major revisions of BS2 ) and I also have a SX development kit.

I was thinking of using the SX chip, along with a photo transistor. Has anyone tried something similar before? A few pointers in the right direction would help a lot


-Ben

steve_b

Is the idea to measure shutter speed while taking actual pictures?
I could see a way of putting the phototransistor inside the camera and rigging something up to the switch mechanism to start a count on the stamp/SX.
I guess the trick is to mount the phototransistor out of the way of the film imaging process and to also detect a shutter release (switch pressed).

As far as the programming....you could have a loop that'll run depending on when the switch is pushed....then you jump in to a COUNT for the time the shutter is open....
What's a typical shutter time?
The BS2 measures in 2uS resolution (I think)....but that's something to consider....is it too fast to measure? It might be, by the time the processor gets in to it's COUNT command.

Anyhow, that's part of the fun isn't it! experimenting!

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Steve

"Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."

Benoit

I was thinking of placing a phototransistor inside the camera, and hooking it up with some extremely thin wires (28 gauge or so) to a SX chip. On the outside, I would be pointing the camera to a light source.

On the software side, I was thinking of reading the transistor , then when starts to detect light , count processor cycles until the light is off again. I think this is fairly simple, at least in idea, however I'm a noob at using phototransistors.

Anyone has a phototransistor part number to suggest? Something to hookup to a Schmidt triggered TTL (ala 7414)?

Thanks!
-Ben