Why does my camera show a red glow from another camera’s eye-start sensor that I can’t see?
Asked 11/30/2017
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2 answers
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When I photograph a Nikon D7500, the eye-start sensor above its viewfinder shows a red/purplish glow in the image, but I cannot see that glow with my eyes, even in the dark. It appears when the D7500 is powered on.
Is my camera recording infrared or near-infrared light from that sensor? If so, is there any internal fix, or is this normal behavior with digital cameras? I’d rather not rely on front-of-lens IR-cut filters because of stacking, flare, and compatibility issues with some lenses.
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
8y ago
2 Answers
18
If you only see the effect when the D7500 is turned on but not when the camera is turned off you are almost certainly seeing near-infrared light recorded by the camera taking the photo.
It's fairly common for most digital cameras to record such light. The easiest example I can think of are the near countless photos people have posted in various forums of an infrared remote control for their television pointed at the camera with one of the buttons pushed when the photo was taken.
(If you also saw it when the D7500 were turned off it is possible it could have been a specular highlight from your lighting reflecting off the exterior coatings on the Eye-Start sensor - but that does not seem to be the case since you don't see it if the D7500 is turned off.)
Originally by user15871. Source · Licensed CC BY-SA 4.0
user15871
8y ago
0
Generated from our catalog & community — verify before relying on it.
Yes — this is most likely near-infrared light from the D7500’s eye-start sensor, which your camera can record even though your eyes can’t see it. That’s normal for digital cameras.
Most digital sensors are naturally sensitive to some IR/near-IR, so cameras include internal IR-cut filtering. But those filters are not perfect, and some IR can still get through. A quick way to confirm this is to photograph a TV remote while pressing a button; many cameras will show the remote’s IR LED as a glowing light.
This is not considered a defect, so there usually isn’t an internal “fix.” Your camera likely already has an internal IR-cut filter, just not one that blocks all near-IR. An external filter may help in some cases, but it can also affect visible red light and complicate normal shooting.
So in short: yes, your camera is seeing near-IR, and this is expected behavior rather than a fault.
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