Shorting thee wiresatonce

This seems to me to be an extraordinarily simple problem, but it is eluding this old brain of mine. I have built a camera rail for time lapse photography and will be triggering the camera shutter with a remote shutter release (electrical) and an arduino mini pro. The issue is that there are three wires (red, yellow, white) that under normal circumstances all short together at almost the same time. I have found that if I short a yellow and a white wire, the camera focuses. Then if I short a red wire to the other two, the shutter is released. Shorting the red wire to ether of the others alone does nothing. It seams that all three must be shorted to release the shutter.

I thought about using two reed relays but that seems a bit kludgy and might be asking too much of the mini ports.

Any ideas, or am I over simplifying (or complicating) the issue?

What's the voltage between the white and yellow wires?

I'll wager money that either yellow or white is the camera's digital ground, and the others get shorted to ground.

If that turns out to be correct, you can do it with just a pair of transistors or fets.

If it is for some reason more complicated than that, you're probably looking at relays. Check the specs to find ones that don't use much current to close. There are small wimpy relays that can't switch large loads, but which can be driven directly off an I/O pin (don't forget the diode to clamp the back emf) - or you can use one of the relay boards that has a transistor on board to switch the relay coils.

I imagine you need to trigger focus first and allow it enough time and then trigger the shutter.

And, regarding your Title, there is a HUGE difference in computer terms between doing things "at once" and "at almost the same time". The latter is trivially easy.

...R

DrAzzy: One of the strange things about this is that I can read no voltage between red and white, Yellow and white, or red and yellow. I have three multimeters and I tried all three and found I could not read anything.

I believe that the white is common or ground, Yellow and white will focus, but all three seem to be required to release the shutter.

I am not sure I am up to designing a solution that uses trans or fets, so I am hoping I can do it otherwise. My experience with setting up transistor circuits has been limited to stealing someone else's design and applying minor tweaks.... (ashamed to say). I will play around a bit and see if I can figure something out.

Robin2 I used "almost" because I did not know if there needed to be a very small lag between when all three came together. I have since experimented more....

If I short red (shutter?) and white (common?) together nothing happens until I add yellow (focus?) to the other two. The shutter is then released, but I've noticed that it doesn't seem to complete the process (display the picture on the LCD or allow the shutter to be released again) until there a a brief break between yellow and white.

I am still left thinking that all three have to come together, allow the shutter to fire, and then come apart.

Who'd a thunk it.

Thanks for the reponses so far.

I guess I will see what I can find for low draw relays and maybe do some bread boarding with transistors.

crchisholm:
If I short red (shutter?) and white (common?) together nothing happens until I add yellow (focus?) to the other two.

It seems to me completely illogical to think of the problem in that order.

...R

Robin2: You may be right, but you don't say why. Clearly, I am thinking of the problem the only way I know how. If I was sure that I had a clear picture, I probably wouldn't be on here asking about it. Also I may be in the wrong forum. I took this to be where I would go for guidance with a project and telling me my way of viewing the problem is illogical doesn't seem to give me enough info to understand WHY it is illogical.

My guess is, with 5 gold stars and 15k+ posts, you could actually offer some guidance if you wanted to.

5V, 11mA coil relays are readily available.

Do the wires behave differently if the camera is set to manual focus (I assume you can do that)? Do you nerd it to focus every time?

crchisholm:
Robin2: You may be right, but you don't say why.

Sorry. I thought it would be obvious that the camera would need a small amount of time after the focusing mechanism is switched on to allow it to focus on the subject before the shutter is triggered to take the picture. As far as I know that is why they are switched separately.

...R

Lots of info, even Arduino diagrams, if I Google "camera remote shutter diagram" (images).
Leo..

ChrisHigs: no, they don't. The camera is set to manual focus, but I still seem to need all the wires (focus, release, and common) to be shorted together to release, and then separated to reset the camera for the next shot.

CrossRoads: it seems that a single DPDT would do the trick. I think 11ma coil current could be handled directly by the arduino digital port, right. This would be a very simple solution if it works?

Robin2: I will be shooting in manual focus, so no time is needed for focussing. Unfortunately, the Nikon doesn't seem to care... It still seems to require all three wires.

I am hoping I can use one of the relays CrossRoads suggested as a solution

I'm assuming that this a camera remote that electrically works just like the shutter button.
A half press focuses and then a full press triggers the shutter.
So for this you would have 3 wires.

  • ground
  • focus
  • shutter.

I would not see the need to connect them all at the same time. I'd connect the focus then the shutter.
The camera s/w is probably looking for them in that order which would explain why you can't just connect the shutter wire
without the focus wire.

If you google around there are tons of examples that show how build circuits using and arduino to trigger these types of remote inputs. Many are using optical couplers.

Just change Wawa's search to "Arduino camera remote shutter diagram"

crchisholm:
Robin2: I will be shooting in manual focus, so no time is needed for focussing. Unfortunately, the Nikon doesn't seem to care... It still seems to require all three wires.

Well as you did not bother to tell us you can hardly blame me for being confused.

What happens if you connect the focus wire so it ON all the time ? Then you would just need to trigger the shutter wire ?

If that does not work then, as said earlier, including by @bperrybap, just connect focus first followed by the shutter.

...R

What's the model / manufacturer of your camera? Without this information, its just a guess as to what the wire / pin functions are.

Computerized Shutter Control of Canon DSLRs

NIKON MODIFICATION – for the Canon DSLR PC Serial Port Control Cable

I think I have done a poor job of presenting this and I am sorry for that. My original query simply to find a way to short three wires together using the arduino and. I think CrossRoads did steer me to a good posibility with the low power DPDT relay. My focus (PTP) was on that...not so much the camera itself....but the camera is a Nikon D90.

Robin2, as I stated earlier, the wires must be separated or the camera will not reset for the next picture. I have done a butt load of testing to see what would work and what wouldn't.

I think this might be a good example for someone's book. "When simple posts go bad" Sorry.

I did determine that the red (release) and yellow (focus) can be wired together and when shorted to the white (common) the camera seems to release normally and reset afterwords, but sinse I don't know what goes on behind the scenes, I will use a DPDT relay to connect and disconnect all three lines.

I guess the only other question for right now is if it is safe (for the arduino mini) to activate the 11mA coil directly from a digital port (using a protective diode of course)? I should be able to find that in the specs.

Maybe try and give http://www.dropcontroller.com/ a quick read - came across that a few days ago... I even registered here specially to share the link! Site has a bit of info about shutter, focus, flash,,,

crchisholm:
Robin2, as I stated earlier, the wires must be separated or the camera will not reset for the next picture. I have done a butt load of testing to see what would work and what wouldn't.

In that case the next thing I would consider is separately shorting the focus and shutter wires - with the focus wire being connected first. Then the shutter connection could be made at the moment appropriate for the photo.

Nothing I have read so far suggests a need to connect focus and shutter at the same instant.

...R

seems like two 10 cent FETs would do the job.
turn on the FET to the focus wire, wait a few ms then turn on the FET for the shutter.
wait a few 10s of ms then turn them both off.

--- bill

Check this link also...
"Using an Arduino and a optocoupler to activate a camera shutter" by Martyn Currey
http://www.martyncurrey.com/activating-the-shutter-release/

Thank you again, CrossRoads. Got one of the DPDT low power relays you suggested and it works perfectly. I've hooked it to digital pin 3 and ground on the Arduino Mino pro. One pole of the wiper (not sure of the term for a relay) goes to the release line, the other goes to the focus line and both NO go to the common. Works great.

The key piece of info was the low power relay...didn't know I could get a relay that drew less tha 20mA.

Thanks again.

I'm not an electronics engineer, but I play one on the Arduino.