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Author Topic: Transistor versus optoisolator for Canon camera trigger  (Read 1732 times)
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Hello,

New to this forum and a novice with electronics, so pardon me if this is a really silly question. As one of my early projects, I want to use an Arduino Uno to trigger the shutter of my Canon camera. Canon professional cameras, as you may know, use a shutter release cable comprising three leads: two hot ones for focus and the actual shutter release with the third being for ground. I'm only concerned with the one for shutter release. Short it to ground and the camera fires. So, how to do this with the Arduino? I've seen others use optoisolators to keep the camera's shutter release circuity completely independent  of system current. Can I use a simple transistor instead? Is there a real risk of connecting the camera's shutter release circuity to the common ground?

Apologies if I haven't explained this correctly.

-David
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Hello,

New to this forum and a novice with electronics, so pardon me if this is a really silly question. As one of my early projects, I want to use an Arduino Uno to trigger the shutter of my Canon camera. Canon professional cameras, as you may know, use a shutter release cable comprising three leads: two hot ones for focus and the actual shutter release with the third being for ground. I'm only concerned with the one for shutter release. Short it to ground and the camera fires. So, how to do this with the Arduino? I've seen others use optoisolators to keep the camera's shutter release circuity completely independent  of system current. Can I use a simple transistor instead? Is there a real risk of connecting the camera's shutter release circuity to the common ground?



Apologies if I haven't explained this correctly.

-David

You can use either two (or one), transistors (with base resistors) , optoisolators (with LED input current limiting resistors), or even small 5 vdc relays to perform the functions. Circuit isolation is not required in this application but many like to do it anyway.

 I'm a fan of using small reed relays for such functions but people call me an old foggy, but that way I don't have to think too much about what the camera's contact operating voltage is, what the polarity of the contact interface is or how much contact current is being switched when activated, I'm just wiring 'dry contacts' to the camera. Here is one that can be directly wired to an arduino output pin, (but do wire a reversed diode across the relay coil terminals for transient protection) as it only draws 10 millamps from the output pin to operate, plus you gain total electrical isolation between the arduino and the camera.

http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_1860070_-1

Lefty

« Last Edit: January 30, 2013, 10:45:44 am by retrolefty » Logged

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For such a small difference in price between an optocoupler and a simple transistor I wouldn't risk my camera.
Lefty, this reed solution is nice as well.
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Thanks both. I've got a few optoisolators coming in the mail now. Hypothetically speaking, what type of circuit could I wire up to make the transistor method as safe as possible?
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for the idea u have u dont need to isolate at all. the shuter input is cmos and dont draw any amp
connect common to ground and both focus and shutter to any digital pin.
will take picture when low for at least 10ms (reliably)

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