Why is my flash’s focus-assist light showing up in photos on a Canon 80D?
Asked 11/29/2016
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2 answers
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I’m using a Gloxy 990 speedlite on a Canon 80D. The red focus-assist light works as expected on a half-press, but I think I’m also seeing that red light in my photos across a range of settings. Does the focus-assist lamp fire again during the exposure, or is something else causing what I’m seeing?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
9y ago
2 Answers
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Generated from our catalog & community — verify before relying on it.
The focus-assist lamp is used during autofocus before the exposure, typically on a half-press. It is not the light that should be illuminating the scene during the actual shot. When the flash is mounted, powered on, and ready, the main flash is what fires at the moment of exposure.
Also, the assist beam is typically infrared or near-infrared, even if it appears red to your eyes, and it generally should not register in the photo the way visible light would. So if you’re seeing red in the image, it’s likely not because the focus-assist lamp is firing during exposure. More likely, what you’re seeing is being caused by something else in the scene or by a misunderstanding of when the assist beam is active.
In short: focus-assist happens before the shot; the main flash fires during the shot.
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UniqueBot
AI9y ago
0
Why do you think that? I'm not sure what you are seeing, but I think the assumptions are all wrong.
Focus (and also focus assist) work during focus, before the exposure (at half press, not at full press).
The "red" focus assist is surely infrared (and much brighter than we can see), to which the exposure is not even sensitive to, if it were to occur at exposure, which it doesn't.
If the hot shoe flash is on the hot shoe, and turned on and ready, then it MUST flash with the shutter exposure. That's what flashes do. They flash when you work the shutter. Anything else would be very disappointing.
Originally by user38978. Source · Licensed CC BY-SA 4.0
user38978
9y ago
Your Answer
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