how to test a speedlight for issues?
Shot a wedding saturday night and had 2 580-ex2s with me and 2 bodies. One was way more powerful than the other so I tested them by swapping flashes, changing batteries, etc.
Yes, one was definitely under by about 2 stops (FEC +2 balanced things out).
OK...monday is here and I"m in teh studio and guess what? I can't get the flash to act up...I have 3 580s and all do the same thing - darkened the studio (not as dark as the hall was though) and using a flash meter as well as the histogram on the camera, direct and bounced (which is how I used them at the event) and all three read the same on both the meter and the histogram and look the same on the LCD.
So....other than maybe it being a heating up issue (of the flash - tried multiple batts, fresh, from the good flash, alkalines as well as 2 brands of nimh) I don't see an issue.
So how does one test a flash? If I can't replicate the issue sending in to canon won't do me any good as they'll find nothing wrong.
Vision without execution is hallucination. T. Edison.
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