The Ten Most Frequently Asked Questions
Click here for many more questions.
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Can I trigger my camera's electronic shutter with a photogate or other trigger?
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I'm just getting started in high-speed photography. What kinds of triggers do you recommend?
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Can I trigger a wireless controller such as a PocketWizard with a HiViz circuit?
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My flash doesn't have a PC cord. How do I connect it to the trigger?
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How do I get a trigger circuit to discharge a Nikon SB-600 flash?
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What's the difference between the various types of photogates?
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Is the SK2 sound trigger sensitive enough to capture a water splash with the sound of the splash?
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Do HiViz circuits output a voltage that can hurt my flash unit or camera?
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 do its thing. Our triggers and delay unit will trigger either flash units or camera shutters that have electronic shutter cables. In order to do the latter, you'll need to cut your remote shutter cable in order to splice it to the trigger or delay unit output. The remote cables usually have 3 wires. Shorting 2 of them together performs the autofocus and exposure operations of the camera. Shorting the 3rd wire to the other two closes the shutter. You would use the output of the trigger or delay unit to perform the latter function.
Some cameras have shutter cables designed especially for DIY projects. An example is the Nikon MC-22 remote cord which works with the Nikon D series cameras with the exception of certain models (see below). The cable ends of the MC-22 are blue, black, and yellow. Shorting the blue and black ends together does the autofocusing and exposure operations. Shorting the yellow cable to the other two actuates the shutter.
Cameras with infrared remotes such as the D70/70s aren't well-adapted for use with our triggers. While you might be able to wire a trigger directly to the remote, the shutter lag may be unacceptable for high-speed applications. See this link for a discussion.
A sound trigger, photogate, and delay unit cover many situations. The SPG1 style photogate provides for flexible positioning of the emitter and detector. You can also replace the infrared LED with a red laser pointer in order to operate the photogate over large distances. A delay unit is often used with a photogate. If, for example, you want to photograph splashes, you need to delay the discharge of the flash from when the drop passes through the photogate until it reaches the water's surface.
When using the sound trigger, delays are usually set according to the distance from the source of the sound to the microphone. Figure a delay of about a thousandth of a second per foot (30 cm) of distance. If you need particularly long delays, then it becomes convenient to use a delay unit. You can use the same delay unit as for the photogate.
The delay unit can also be used with a contact trigger. See this page about contact triggers. You would simply connect the two wires from the contact trigger to the input and the ground of the delay unit.
3. Can I trigger a wireless controller such as a PocketWizard with a HiViz circuit?
Here's a comment from Scott Thorson: "I spent some time last night working with the flash triggers (sound and photogate) and my Pocket Wizard Plus II’s. I can definitively say that it works. Using the same flash outputs (1 & 2) from the circuits set up for Canon flashes, I can trigger the PW’s. I successfully triggered the PW’s from the “camera/flash” mini plug port (on the top near their antenna) as well as from their hot shoe (using a Paramount mini plug to female hot shoe adapter cable). This worked wonderfully and allows me to trigger several flashes and my camera as well, so I can take shorter exposures and not have to have the room totally dark to get the same effect."
4. When using a HiViz delay circuit to trigger my Canon 430ex or 580ex flash, the flash unit is disabled after each discharge until I turn the unit off and on again. What can I do?
Versions of our kits prior to v10 used the 22-kΩ resistors shown in this photo. If this is what you're using, try replacing the 22-kΩ resistors with 1-kΩ resistors. Or try this method reported by Brad Steel: Connect a 4.7k resistor in between the delay SCR output and the flash wire. We think this has the effect of limiting residual current in the Canon trigger circuit that would otherwise keep the SCR closed.
5. What is the maximum separation of the emitter and detector of the SPG1 or TPG photogates? I'd like to have the circuit trigger on birds breaking the beam of the photogate.
Beyond 4 inches of separation, alignment of the emitter and detector is especially critical and sensitive to small changes. For large distances, a red laser pointer can be used in place of the infrared LED. The detector is sensitive to red light as well as infrared. When using a laser, you may need to place a pinhole aperture in front of the laser so that the beam on the emitter isn't too intense. (This tip comes from Roy Marshall.) Note also that a red spot may appear on the subject so try to arrange things so that the red spot will be on the opposite side of the subject as the camera. Alternatively, you might be able to edit the red spot out of the photograph.
6. My flash doesn't have a PC cord. How do I connect it to the trigger?
If your flash unit doesn't have a cord, it must have connections on the foot for triggering it. You can get an adapter shoe that fits on the flash foot and has an output PC cord. You should be able to find these in camera stores or purchase one from the HiViz store. More information on making connections is found here.
7. How do I get a trigger circuit to discharge a Nikon SB-600 flash?
First put the SB-600 in manual mode. Then you'll need a way to attach the SB-600 to the trigger circuit output. See the following link for a way to do that.
http://strobist.blogspot.com/2007/12/easy-nikon-sb-600-sync-jack-mod.html
Thanks to Tom Denham for the information above.
The
SPG1 is more flexible than the SPG2, because the emitter
and detector of the SPG1 can be positioned independently
of each other. Objects of various sizes can pass through
the SPG1 photogate. The SPG2 uses an interrupter as
shown to the right. The emitter and detector are fixed
in position in a plastic housing. This is convenient
for triggering on drops but is limited to objects that
can pass through the gate. You can use either type of
photogate with the same base trigger circuit.
The SPG is the most universal and works for nearly all applications. An exception might be very fast and small projectiles that are in the beam for a very short time. The TPG has a faster response and is designed for the latter situation.
9. Is the SK2 sound trigger sensitive enough to capture a water splash with the sound of the splash?
The SK2 is designed to trigger on loud and sharp sounds such as that of a balloon burst, hand clap, or finger snap. In order to capture water splashes, a photogate with delay is the recommended trigger. The drop passes though the photogate and starts the delay timer. After a preset delay, the delay unit triggers the flash unit or camera.
10. Do HiViz circuits output a voltage that can hurt my flash unit or camera?
No. The output stage of the trigger and delay circuits is simply a short circuit. The latter is what is required to trigger most flash units.
