I was planning to take a fake multiple-exposure picture: use a dark room, long exposure time, and manually trigger a flash for each exposure. But can I trigger my Canon Speedlite 430EX II manually without any extra gear?

This would be trivial if I had two camera bodies, but no such luck.

Of course there is the test button in the Speedlite unit. But exactly what does the test button do? How much flash power do I get this way; can it be adjusted by using the manual mode? Is it just a tiny burst of light so that I can see that the unit is alive, or can I use the test button to get consistent exposures?

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    \$\begingroup\$ Test button is used for measurement of light, so it would be surprising if it didn't give the expected power. \$\endgroup\$
    – Joanne C
    Jun 17, 2011 at 19:20
  • \$\begingroup\$ JoanneC: Oh, I did not know what it is for; I just knew that it triggers the flash. :) \$\endgroup\$ Jun 17, 2011 at 19:28

1 Answer 1


Your test button should firing at whatever power you select manually. I can't speak to that specific model, but it has on a few different flash brands I've tried.

Its pretty easy to tell if it does.

  • Just set it to high, take a picture and press the test button.

  • Set it to low, take a picture and press the test button. Is there a big difference? Probably so.

You should get consistent exposures with it.

If for some crazy it doesn't, you can always electrically tape a couple of wires to the bottom pin and plate and just short the connection together with a momentary push button ( or just touching the wires together)- that's what the camera does.

  • \$\begingroup\$ You are right, I took a bunch of test shots using different flash power settings, and it seems that I get exactly the same flash power by pressing the test button or by letting the camera trigger the flash. I guess I should have tried it before asking, but for some reason I was assuming that the answer is "no, it's complicated"... \$\endgroup\$ Jun 17, 2011 at 19:01
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    \$\begingroup\$ +1 - I used to do that, though now I just use radio triggers and hold the transmitter to use its test button. Lets me move the flash around a lot more as well as use more flashes. \$\endgroup\$
    – Joanne C
    Jun 17, 2011 at 19:19
  • \$\begingroup\$ @JoanneC - Radio triggers with its test button - thats what I do. \$\endgroup\$
    – rfusca
    Jun 17, 2011 at 19:21

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