I'm fairly new at Arduinos, but I wanted to know if the following scenario is possible. I need to attach multiple DSLRs (a Canon 7D) N3 connectors together to an Arduino so I can trigger them at the same time. I thought about using a PC with USB connections but there is a delay between triggering each camera (probably due to iterations of instances). I thought about splicing all the shutters together and all the grounds together but wouldn't the second camera (once it's plugged in), begin triggering the first?
with the low level port commands you can set multiple output lines of an Arduino in one instruction.( 62.5 nanosecond)
check - Arduino Reference - Arduino Reference - you need to learn a bit about bit operations and masking, not really difficult, just spending one evening to dive into it.
example
PORTD = PORTD | B10101000; // OR-ed -> sets digital pins 7,5,3 HIGH, leaving rest as is
PORTD = PORTD & B01010111; // AND-ed -> clears digital pins 7,5,3 HIGH
If you can find out the maximum current either from a datasheet or empirically by connecting an ammeter in series (it seems a shame to have to cut into such a nice looking cable) and verify that it is not more than 30mA , then you can use the ADG512 Analog switch designed for 5V operation (meaning each switch has a DIGITAL (0/5v TTL compatible) control line. The analogsignals are connected to the switch pins and the arduino digital control line is connected to the digital control pin. Alternately you could use relays (see attached and following link) http://www.ebay.com/itm/5V-One-1-Channel-Relay-Module-Board-Shield-For-PIC AVR-DSP-ARM-MCU-Arduino-/310566336050 I would keep them all separate rather than in series but I'm not a photographer. If you build a mounting plate with N3 recepticles and connect all the pins IN PARALLEL to the N/O contacts of a single relay that might work just as well. The only difference I see is that if you are running HIGH SPEED film and they were connected to separate individual relays, a difference of 10mS one way or the other would be insignificant in any other application but in high speed photography it could mean a noticable difference in the photo.
Since I need the circuit to extend to N cameras, would it be possible to loop the input pin of the opto-isolators to create a parallel circuit?
Yes, but you will need to drive N optos so depending on the size of N you may need to boost the Arduino output with a transistor or other amplifier. Or use multiple outputs. The best way really depends on the size of N and if that will vary or always be the same value.
Since I need the circuit to extend to N cameras, would it be possible to loop the input pin of the opto-isolators to create a parallel circuit?
Yes, but you will need to drive N optos so depending on the size of N you may need to boost the Arduino output with a transistor or other amplifier. Or use multiple outputs. The best way really depends on the size of N and if that will vary or always be the same value.
Rob
Wouldn't using multiple pin outs delay the triggering?
Not if you use port manipulation.
But even without it, you can use one IO pin to control multiple optocouplers in connected parallel, like I said previously.
iTech:
Wouldn't using multiple pin outs delay the triggering?
Frankly, it is unlikely the cameras require very much current at all to trigger them.
Unfortunately, the need to slice up nicely manufactured (and no doubt ridiculously expensive) remote cables, is a consequence of the use of proprietary fittings.
If you can determine that one side of the trigger is grounded to the body of the camera (as it likely is if it has a remote control connector), then you do not need opto-couplers, all the grounds can be connected together and the shutter lines each with a diode in series, pulled low by a single transistor. You may have to do the same with the "focus" control lines as well.
As to whether it matters whether there is a delay of a few microseconds between shutter activation, this is most improbable unless there are a lot of cameras. Even digital cameras do not have shutters that fast (though those exploding resistor pictures were pretty impressive!).
Paul__B:
Unfortunately, the need to slice up nicely manufactured (and no doubt ridiculously expensive) remote cables, is a consequence of the use of proprietary fittings.
You can get cables that have the proprietary camera bit on one end, and a standard 2.5mm or 3.5mm audio connector on the other for most cameras these days for about $10US each. These are made for some of the shutter releases that support multiple cameras. For example, look through this site for the Cactus V5 shutter release cables: http://www.gadgetinfinity.com/wired-shutter-release/. Or if you want to slice cables, you can find various clone (Opteka or JJC) wired shutter release cables on ebay fairly cheaply ($5 or so).
Note, there are some DSLRs that don't support a wired shutter release, but support an infrared shutter release. You can make a trigger via an IR LED fairly simply. And there are a few cameras which have neither wired nor IR shutter release support, and there you would need to rig up a servo to push the shutter button.
Paul__B:
As to whether it matters whether there is a delay of a few microseconds between shutter activation, this is most improbable unless there are a lot of cameras. Even digital cameras do not have shutters that fast (though those exploding resistor pictures were pretty impressive!).
The really high speed shots are done by putting the camera in a dark room, pre-focus, and shoot for a long period of time, and then you engage the flash at the precise time you want (for example, n microseconds after a sound triggers for doing the popping balloon, breaking glass type shots). Typically, you need to do it many, many times to get the timing just correct.
MichaelMeissner:
The really high speed shots are done by putting the camera in a dark room, pre-focus, and shoot for a long period of time, and then you engage the flash at the precise time you want (for example, n microseconds after a sound triggers for doing the popping balloon, breaking glass type shots). Typically, you need to do it many, many times to get the timing just correct.
The really, really high speed photography is done with air gap flashes.
For the really, really, really, high speed photography there is this thing.
But back to the subject.
Synchronizing the triggering of multiple SLR cameras (or any camera with a mechanical shutter) could be affected by slightly different mechanisms in each individual camera, even if they are the same model.
Shpaget:
Synchronising the triggering of multiple SLR cameras (or any camera with a mechanical shutter)
But ... do cameras have mechanical shutters?
MichaelMeissner:
The really high speed shots are done by putting the camera in a dark room, pre-focus, and shoot for a long period of time, and then you engage the flash at the precise time you want (for example, n microseconds after a sound triggers for doing the popping balloon, breaking glass type shots). Typically, you need to do it many, many times to get the timing just correct.
Yes, well, that is of course true, but the camera referenced in this thread seems to be taking pretty fast video with an even faster "shutter" speed and without a strobe. I didn't go and look at the actual specifications for that model.