If your camera has an electronic shutter with a remote shutter release, you may be able to actuate the shutter using an output of your HiViz trigger circuit. This is a useful thing to be able to do if you're, say, photographing insects, birds, or other unpredictable subjects. You simply can't hold the shutter open waiting for the subject to appear. Another application where it's useful to trigger a camera is in splash photography. The immediate output of a delay unit can be used to trigger the camera and the delayed output to trigger a flash unit. The camera exposure time can be set so that the shutter remains open just long enough for the splash event to be completed.
These instructions describe the most basic and least expensive way to trigger a camera shutter from a HiViz trigger or delay circuit. Note that this method does not completely isolate your camera's circuitry from the HiViz circuit. However, since your camera will be connected to an SCR output, which acts as a simple switch, there is effective isolation from the trigger circuit. I've used this method for years and never damaged a camera by doing so. (I've done a lot more damage by dropping cameras over the years.) Nevertheless, if you're concerned about the possibility of damage, consider using an optoisolated switch instead. See the Camera Opto-Switch.
Since you're still reading, I assume you're going ahead with the DIY version. Here's what you'll need:
The remote shutter cable for your camera and the willingness to cut it in two or destroy the pushbutton remote. If you purchased the original equipment cable (for example, Nikon's MC30 or Canon's RS-80N3 or RS-60E3), you probably paid a lot of money and aren't sure you want to cut your investment in two. If so, search online for replacement cables from third-party sources. Amazon.com is a good place to start. You should be able to find inexpensive cables (and low shipping costs, too) that you can use for this project.
Your HiViz trigger or delay circuit. This method is compatible with all HiViz trigger circuits.
- 3 pieces of hook up wire about 6" long each, preferably 3 different colors, 22-gauge, single strand
Tools: wire stripper, needle-nose pliers, 15-30W soldering iron, multimeter for testing connectivity (optional)
- Supplies: solder, electrical tape or heat-shrink tubing (~3/32" dia)
In case you're wondering about what cable your camera uses, the table below shows the ones used most often. All of these cables terminate in a pushbutton switch of some kind. That's the end you're going to cut off. The important part is the camera plug, since that's what plugs into your camera. Many of these plugs are non-standardized, so you can't just go out and buy the plug. An exception is for cameras that use the Canon RS-60E3 cable. That cable uses a standard 2.5mm stereo plug. You can get one at Radio Shack if you want to make up your own cable.
Here's the table I mentioned above. Click on the images for larger views.
What you need to know about all these cables is that that are three important wires. I'll call them the shutter, focus, and common (or ground) wires. Here's how they work. If you connect the focus wire to the common wire, the camera will autofocus. If you then connect the shutter wire to the other two, the shutter will actuate. This is all that the pushbutton part of the cable does. When you press the button half-way, the camera autofocuses just as if you pressed the shutter button halfway. If you press the button all the way, the camera snaps a picture. Since we're just talking about a switch (actually, two switches), you can use the SCR output of a HiViz trigger circuit to trip your camera shutter. But first, you need to figure out which of the three wires has what function. So now it's time to cut the cable or open the pushbutton remote. Use whichever method below that you prefer or that fits your situation.
Method 1. Opening the pushbutton remote
If your camera isn't listed above, this may be the only method available to you. Open the remote to see where the wires are connected. If the remote is held together with screws, this should be easy. Otherwise, you'll need to crack, saw, or pry it open. Inside, you should find what amounts to a two-stage switch with three contacts. One contact will be common to both stages. Another contact is for the half press of the button and a third for the full press. Be sure to record what functions go with what colors of wire. In order to gain access to the bare wires, you can either disassemble the remote and remove the wires or just cut the remote off. Strip back each of the wires about half an inch. Then skip down to Testing the Cable.
Method 2. Cutting the cable and tracing the wires
Cut the cable in two, leaving about 6" on the end that has the pushbutton remote. While you won't be using that end with your HiViz trigger circuit, you may decide at a later date that you want to reconnect it. So leaving some cable on it will make it easier to do that. Now put the pushbutton remote aside. You won't be using that below. You'll be dealing with the part of the cable that connects to the camera.
Strip back the outer insulation on the cut end about an inch. You'll see at least 3 wires, but there may be more. Strip back the insulation about an inch on each of the wires. Some of these cables are designed to be used with more expensive controllers, and they have more wires for that purpose. In that case, you'll need to figure out which ones of the wires are the three important ones. If you're lucky, there will only be three wires to start with, but you'll still have to identify which of the three functions (shutter, focus, ground) go with which wire. Here's where your multimeter will come in handy together with the diagrams below. What you'll be doing is checking for connectivity between each of the three relevant pins indicated in the photos below and the individual wires of your cable. When you've figured that out, note the colors and functions of the wires for future reference. If your cable has more than 3 wires, cut off the exposed metal strands on the extra wires. Then tape them back out of the way.
Testing the cable
Here's a way to test if you've identified the wires correctly.
- Start with your camera turned off. Connect the shutter cable to the camera. Make sure the bare wires on the other end aren't touching each other.
- Now turn the camera on. Put it in a mode that will autofocus and make sure that the subject is far enough away that the camera will allow a photo to be taken.
- Next you'll work with the bare wires. Hold the focus wire against the common wire. The camera should autofocus. While continuing to hold these wires together, touch the shutter wire to the other two. The shutter should actuate.
I always like to remind people about this...
Solder in a well-lit, well-ventilated, open area. Avoid contact with all metal surfaces on the iron.
Keep the tip of the soldering iron clean by wiping it against a wet sponge or towel before and after each use. A clean tip should look shiny and silvery; any yellow or black material on the tip will get into the solder and may weaken your solder joint.
Once the tip of your soldering iron is clean, touch a bit of solder to the tip just before use. This is called tinning, and helps the solder run more evenly.
Heat the connection to be soldered by holding the soldering iron to it, until solder applied at the junction between the two melts and flows freely. This ensures the connection and the solder are both hot enough to yield a good solder joint. This should take no more than 10-15 seconds. After the connection is heated, try to get solder along the entire length of the connection by briskly moving the solder and iron along.
Avoid touching only the solder to the connection, and then the soldering iron to the solder to melt it onto the connection. The connection will be cooler than the melted solder and won’t form a good solder joint.
- Let new solder joints cool for several seconds before examining them. There should be solder all the way around the connection, forming a rigid joint. When done, unplug your soldering iron and let it cool.
Soldering leads onto the wires
You probably found that the small wires coming out of the shutter cable were difficult to deal with. Besides being small, they have multiple strands and are too flexible to push into the breadboard of your trigger circuit. So in order to make connections easier, solder on to the wires stiff pieces of 22-gauge single strand hook up wire. If possible, use insulation colors that match those of the shutter cable. That will help avoid confusion. Here's the procedure for soldering on a wire lead:
Click for larger image
|Strip back the insulation on the hook up wire about half an inch. Then wrap shutter the cable wire tightly around the stiff wire.|
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|Solder the connection. The photo shows all three wires soldered.|
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|Shrink heat-shrink tubing around the solder joints or wrap with electrical tubing if you don't have tubing.|
Finally, strip back the ends of the wires about an eighth of an inch and you're ready for using the cable with your trigger circuit.
Triggering your camera with your HiViz circuit
I'll show you how to do this with a sound trigger/delay. The method is similar for other trigger circuits. See the photos below with captions. Note that for my cable, the shutter wire is red, the focus wire is yellow, and the common wire is white. You can click on the photos below for larger versions.
For the example above, the shutter wire is connected to the delayed output. Therefore the shutter will be delayed by an amount depending on the setting of the blue and brown pots. You can also connect the shutter to the immediate output of the delay unit or to the direct output of the sound trigger.
For repeated triggering events, the camera shutter should
actuate repeatedly as long as you keep the shutter, focus,
and common wires connected to the breadboard. In some instances--and
this may depend on your camera--the shutter may be disabled
after the first event. If this happens, a reset is necessary.
You can effect a reset simply by disconnecting and reconnecting
the shutter wire. Another way to deal with this is to replace
the SCR with a 2N2222 or other general-purpose NPN transistor.
Insert the transistor in the same holes with the same orientation
as the SCR. This will likely eliminate the need to reset
the camera. Caution: When triggering a flash unit
rather than a camera, we recommend against the transistor
replacement just described, as the SCR protects the trigger
circuit from the voltage across the flash terminals.
You may find that your camera's LCD screen doesn't display the photo you've taken. Don't worry; there's nothing wrong with your camera. You have to disconnect the focus wire in order to enable the LCD screen.
For some situations such as a steady stream of drops falling through a photogate, you may not want your camera to go off repeatedly in quick succession. If you have the camera connected to the delayed output, you can increase the reset delay according to the method described here.