Update on the project.
Got a Pi 3B+
Followed the guide for the shutter release (using octocouplers instead of transistors, as I found in an update to the original guide).
Have a basic prototype for using LDRs , but might need a way to convert the analog signal to digital.
Have more questions, and a desire to reduce latency in the circuit design.
Hope to contact the author with some questions.
Ordered the lightning detector circuit, put it on the backburner for now (still interested though).
So, that tl;dr got a little bit long, but it sums it all up pretty well. I'll go into a bit more detail here and ask a few questions as well.
First, the link to the update to the original guide: https://scribblesandsnaps.com/2015/02/2 ... ocouplers/
I managed to not see the link to the update near the end of the first guide until a few days ago. I think the transistors cost about $2, and will be useful in other projects, so no loss there.
The prototype octocoupler I made according to the guide seems to be functioning, in the sense that it is reducing resistance across the correct wires (focus to camera ground, and shutter to ground) when the led is on, but I don't know how much resistance is tolerable/recommended for the wires leading to the camera. There are varibles- like led brightness, LDR design resistance, and what percent of the light is actually hitting the LDR (my prototype now is using green electrical tape, but I have heat shrink for the real deal).
I've found and glanced at a few component sheets to look at response times, but not done any serious calculations yet. I've already got all the parts for the project (minus a possible need for an analog to digital converter), so the experience gained makes this worthwhile to me even if the project does not succeed.
I'm using a fairly cheap multimeter right now, but not getting any idea of response time in the circuit. Is there a good way to measure this, perhaps through a little circuitry or having the Pi read out signals at pins (with timestamps or similar).
Another latency source that I have no idea about is how long the lightning detected signal will take to be handled by the Pi and sent to the focus/shutter wires. The scripts I have used are in python, is this a good way, or should I look into another method?
Focus/shutter delays- the program in the guide has a half second delay between focus and shutter. That's fine for general use, but I do not know if that is just a generic value, or a minimum. If it is identical to the way the camera button works (half press to focus, full press for shutter), it should be fine to have no delay between the two signals. I will have to look more into that, as well as pre-locking the camera focus.
Well, that thing is just really cool, so I got it. I am in pretty deep already with the LDR method of detection right now, so I will look into making more use of the lightning detector when I have finished the LDR method.
The programming aspect of things has been a challenge for me, but the scripts have been short enough and usually commented well enough for me to be able to figure out what is going on, and make basic customizations to them. I'm sure this is the area I will need most help in, but I don't have specific questions just yet.
The LDR will have a drop in resistance when light hits it. This will produce a voltage drop? How would I convert that to a usable signal for the Pi? I need to do more research, but it seems like an ADC would be useful here?
If you made it here, thanks for reading. Please don't feel obligated to answer all of the questions, many of them are partially here in part to help me conceptualize what has been done and what needs doing.
If anyone is interested, I have a few pictures / short movies at various stages of the project.