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I got a pair of "no name" strobe lights with a simple hot-shoe trigger and trying to use it with EOS 550D. Although it seems to work at first glance (strobes fire when shutter is triggered) in fact they don't make any difference to the picture.

Camera is set on Manual mode - 1/125 F1.8 ISO 100 - and both with the strobes on and with them turned off the image is exactly the same.

I suspect they fire too early or too late, not when the curtain is open. I have disabled red eye correction but can't do much else in the Flash control menu - all the menu items are disabled because the hot shoe trigger is not a Canon brand I suppose.

Any ideas or pointers to what could be the problem and how to set up the camera for use with strobes?

Thanks!

  • What do you mean by "simple hot-shoe trigger"?--radio slaves? It sounds almost like you're using built-in optical slaves in the strobes with the 550D's pop-up flash. – inkista Jul 12 '15 at 15:38
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    Is your hot shoe trigger optical or radio? – Michael C Jul 12 '15 at 18:49
  • What is the guide number of the strobes and how far are they from the subject? How much ambient light is in the scene? If you are shooting in bright daylight it takes a LOT of strobe to make any difference. – Michael C Jul 12 '15 at 18:50
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    @MichaelClark - They are radio controlled and the strobes are close to the subject (half a meter) and there is very little ambient light. In fact when I tried with build in pop-up flash with the same manual settings it made a significant difference on the picture. But these massive strobes don't. I strongly believe they fire too early or too late. But why? – MLu Jul 12 '15 at 22:28
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    Have you tried using a slower shutter speed? Like 1/60th second? – Harry Sanderson Jul 16 '15 at 13:28
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As some have pointed out, it could be that your camera is somehow in E-TTL mode and triggering the strobes through the pre-flash. If so, make sure that your triggers are compatible with the 550D and that they're making a solid connection. Quite often, triggers can seem like they're attached properly when, in reality, they're not seated all the way (or properly mated with mount).

Also, knowing the model of your radio trigger will help. I've heard stories of people buying radio triggers off of eBay that ended up having a really poor flash sync (>= 1/125 shutters even).

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If you are using the pop up flash to trigger your lights you will need to press the * button before you take the shot.

(The * button is the flash exposure lock button, if using this button, remember to let your lights recycle before taking the shot, your lights will fire twice. Once when you press the * button and once when you press the shutter release. )

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Make some tests.

  • Try setting your camera in rear courtain and see if that helps.

  • Lower your shutter speed. (I do not think this would make a diference, because you would have noticed a brighter band already but try)

  • If they have an optical slave, and you can change the power, lower it and trigger them with your pop up flash.

  • Take a shoot directly to the flashes. If you see a small trail of light there is a chance they fired sooner.

  • Test them on another camera. If they work it is your camera the one that is not syncronized.

  • Test your camera with another trigger, perhaphs a cable one.

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You can do this with your DIGITAL camera by shooting a bunch of test shots with your camera but a light meter is so much nicer.

You need a light meter that will do flash metering. Set the iso on you meter to the iso setting you are using on your camera, use the slave to trigger the strobes while holding the light meter at the location of the subject. do this for each strobe independently so you know how much light each strobe is putting out. This will give you a reading of shutter speed and fstop needed for you to set your camera. You will need to calculate, either manually or in the light meter, to bring the shutter speed down to at or below your flash sync speed needed for your camera. you can make adjustment to you strobes power settings or by moving them closer or farther from subject to affect the fstop you desire.

EDIT - you need to have your camera in manual mode. You are the brain making the decisions and setting the controls of your tool (camera) in this scenario.

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