Why does my Canon 5D Mark III severely underexpose with a 600EX-RT in E-TTL II evaluative mode?
Asked 2/14/2013
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2 answers
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I'm using a Canon 5D Mark III with a Speedlite 600EX-RT and EF 17-40mm f/4L. In Program mode, with the flash pointed straight ahead, I sometimes get images that are several stops underexposed when using E-TTL II in evaluative mode. Switching between High-Speed Sync and first-curtain sync doesn't seem to fix it. Bounce flash seems to behave better.
Only tiny areas of the frame may be properly exposed, and they are often nowhere near the active AF point. I'm trying to understand the cause rather than just correcting it with flash exposure compensation. Could this be related to evaluative vs average flash metering, a flash/camera communication issue, or some incorrect flash setting left over from wireless/master use?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
13y ago
2 Answers
5
I have had identical issues with the 580 ex II.
Change the flash setting in the cameras menu to 'average' not evaluative it fixes it. I don't use evaluative for the camera settings without the flash either the same issue happens and photos under exposed. I think Canon need to revisit their 'evaluative' system.
Hope this helps....
Originally by user20992. Source · Licensed CC BY-SA 4.0
user20992
13y ago
0
Generated from our catalog & community — verify before relying on it.
The most likely cause is E-TTL II evaluative flash metering misbehaving, not a need to match the camera’s ambient metering mode to the flash mode. Several users reported the same Canon body/Speedlite underexposure pattern and found that changing the flash metering from evaluative to average solved it.
A reset of flash-related settings is also worth trying, especially if the flash has previously been used with wireless triggers or in master mode. One report noted that entering master mode appeared to restore normal behavior, suggesting a flash setting may have been altered.
So the practical steps are:
- In the camera’s flash control menu, change E-TTL II from evaluative to average.
- Reset flash function/custom settings on both camera and flash.
- Check that no wireless/master/slave settings are still active.
Your camera’s regular ambient metering mode does not need to “match” the flash metering mode. If average metering fixes it, that points to an evaluative E-TTL issue rather than simple exposure compensation being needed.
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AI13y ago
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