trigger voltage and the 10D

Hey there everyone,
Newbie to the Forums and an amateur photographer. I have been doing photos for a fitness model for awhile with a 2.1 mp Sony Mavica CD1000. The quality of the pic isn't great but I have tried to make do. I bought an Interfit 250s colorflash strobe and have been triggering it with a Wein Peanut Slave using the cameras built in flash. The model decided she wanted to start submitting photos to some of the magazines, so I knew it was time for a real digital slr camera, so after looking into it I bought the Canon 10D from B&H Photo along with two lenses. I figured I could just plug the strobe pc cable into the pc port on the 10D, but I saw some websites that said if the trigger voltage on the strobe is too high it can damage the camera. What is meant by this? I always figured the strobe was activated by some sort of a relay that used a little voltage from the camera to trigger it. Is this something to worry about? Thanks for any help.

You can measure the trigger voltage on your studio light. Find the end of the cable where it plugs into the camera, and turn the studio light on and ready. Put a DC voltmeter across the contacts.

Most Canon Speedlites will read 5-6 volts DC. Some big studio lights will read hundreds of volts.

---Bob Gross---

Interfit do an IR transmitter (they call it the IRX) that sits in the camera hotshoe and triggers their range of flash heads. I'm nearly 100% sure the 250 units have the receiver built in.

Cheers

Ian

The PC and hot shoe circuit on the 10D is connected to the shutter and is rated for a maximum of about 6volts. You exceed that at your own risk and the loss of your shutter$$$$$$$. Use a Safe Sync or wireless/infrared system. I use the Pocket Wizard Plus.
Regards,
Scott

Thaks for the reply's. I measured the voltage coming out of the sync cable and it is around 9 volts. Sounds like the IR unit is the way to go. Anyone ever use one? Does it work as fast or as well as a cable hook up?

IR units are limited in maximum distance. The STE 2 has the advantage of wireless ETTL with 420EX and 550EX flashes. You get more distance with radio transmitters like the Pocket Wizards, but you lose ETTL.
Scott

I agree, and had a conversation by e-mail with Canon tech support about this very issue, since I have an older functional flash that I wanted to use via the PC cord. The 10D supports 6-volts and under both on the shoe and the PC socket. Don't go higher, and especially don't go way higher!

Here is some information from White Lightning...I have been using their studio flash units for about 15 years and they are fantastic performers.

Q: I'm using my light with a sync cord. It only fires about half the time when triggered with the camera.
When I fire the light with the test button, it flashes every time. Why is this?A: Some newer (usually digital) cameras will not accept a sync voltage from the flash unit greater than 6 volts; if the sync voltage is greater than 6 volts it can cause misfires. The sync voltages on our X-Series and UltraZAP flash units are all under 6 volts, and are safe for use with digital cameras. Some of our older models of flash units, however, have higher sync voltages. Most other brands of flash units have sync voltages much higher than these, some as high as 50-60V! This sync voltage problem can be easily corrected by inserting a small voltage regulator between the PC & Sync cords. A voltage regulator is a small device that will regulate the voltage fed to your camera, reducing the voltage to a lower, acceptable level for your camera. We recommend the safe sync regulators from both Wein and Paramount.

This problem also can occur when the AC hot and neutral wirings are reversed (when your outlet is improperly wired). Often photographers experience this on location, particularly in older buildings. To find out if this is the case, use a circuit tester. This is a small three-prong device that plugs into the AC outlet and has lights that indicate if there are any wiring problems. You can pick one up at home improvement and electrical supply stores for a few dollars. If you shoot a lot of location, it’s a good thing to have along in the equipment bag.

I have both the STE 2 and a Wein safesync (hotshoe) with a 10D and Bowens light setup. The STE 2 works fine until you want to something like put a strobe behind the backdrop, then it often wont fire. As a rule I use the wein if I am using a tripod otherwise the STE2 (which is my preference). The Bowens units all have built in slaves and they are pretty sensitive.

The STE2 transmits a red/infrared signal. Like anything optical, it can be bounced using a mirror. Stick the STE2 on the camera, and put a mirror at the far right or left of the scene, just out of frame, and align it so that the strobe behind the backdrop can see the mirrored STE2 signal.

---Bob Gros---