So i'm pretty new to electronics and have managed to get my head around the programming side of my Freetronics Eleven (Arduino UNO) board.
My project should be rather simple. I'm looking at creating an intervalometer for my Canon dslr, that also has it's own lightmeter. What I am trying to work out is what resistors I require for the camera connection and the Freetronics lightmeter module. Also from my reading it seems I also require an octocoupler. I have a 5v Besta BR-500 relay, some people on this board have said I can use this with a diode. Will that offer the same protection to the camera?
Also from my reading it seems I also require an octocoupler.
No, you probably only need an optocoupler. (unless you have deviant designs on cephalopods)
I don't understand the question about the light meter.
Canon have gone to a lot of trouble to design a metering system adapted to your DSLR - do you think you can do better with an external device?
I have a 5v Besta BR-500 relay, some people on this board have said I can use this with a diode. Will that offer the same protection to the camera?
The diode will be connected across the relay's coil, so will offer the camera no protection whatsoever (because it won't even be in the same circuit as the camera)
I don't understand the question about the light meter.
Canon have gone to a lot of trouble to design a metering system adapted to your DSLR - do you think you can do better with an external device?
That is true however a cameras exposure can only be altered in 1/3 increments. When shooting a timelapse of a sunset for instance you'll end up with a much smoother transition from day to night by shooting in bulb mode and altering the exposure by smaller amounts.
How would I go about working out what resistors I need?
Changing the exposure when set in bulb mode shouldn't be too much of a problem. When the lightmeter notices a drop in light alter the shutter speed accordingly.
no probs. I figure BULB is the easiest option. I know there is a EOS interfacing library floating around however that opens up some more complications with a USB host etc...
My understanding is that i can program the output pin to set to HIGH (shutter opens) time passes and then at the desired time set it to LOW and the shutter will close. I'm just stuck with the resistors and type of octocoupler required.
I thought the optocoupler would prevent and harm coming to the camera. I've been told that the relay will release a small emp when it is switched off which will fry the board.