EOS Rebel XSi not triggering ring flash

[inventorgeorge]

I am doing some very closeup work with my Rebel xsi. Due to lens shadowing, I need to use a ring flash, connected through the hot shoe. The camera works 100%, as does the ring flash. however, no matter how I set the camera, the flash is not triggered. Using menu, and going to flash control, all items there give me an error message saying that the flash is not compatible.

Is there any way to force the camera to trigger a non-Canon, not "compatible" ring flash unit?

[rs-eos]

Even if it is a light with a duration of 1/50 sec, that is too slow and would greatly restrict your ability to freeze action. You’d need to rely on your shutter speed to freeze action.

Some flash units, when at lower power output, can have durations of 1/50000 (one thousand times quicker) or even faster. Far exceeding shutter speeds.

In your case, you have an incompatible light. And one that most likely has a poor CRI rating. We know its fastest duration is very poor. And total output in terms of a guide number or watt second is probably also on the low end.

If you need to work with flash, pick up a Canon flash (they do make a proper ring light) or third party unit from companies that would have something compatible.

[inventorgeorge]

BTW, LEDs CAN flash! I am an electronic engineer [with a 55 year background], and I use LEDs in many projects, including for short duration, ie flash, applications. LEDs can be turned on and off far faster than incandescent  bulbs, making them actually far better for flash application than anything else.

I really could design and build my own strobe/flash system, BUT I would need to know something about the schematic of the Rebel to do that. I really do not want to reinvent the wheel, only get a ring flash that works with my camera.

[kvbarkley]

"making them actually far better for flash application than anything else."

Other than xenon flash tubes, of course,  which are what are used in actual flash units. I suggest you do a little more market research.

[MikeSowsun]

Is this the one you have? The description for this says it has a continuous, steady on mode.

[normadel]

The answer is plain and simple. Do you have the manual for the camera? If not, view/download it from Canon Support.  On page 100, in the Live View section, it states that a non-Canon flash WILL NOT FIRE.

There's no way around this. On later cameras there is a function called "Silent Shooting" that if disabled will allow non-Canon flashes to fire. On cameras without Silent Shooting you CANNOT make the flash fire in Live View.

In viewfinder mode (not Live View), the flash should fire just fine.