I'd guess because the LED's are brighter than the original lamps and there's more of an exposure discrepancy between them and the ambient light. In other words, the LED's go past proper exposure while the camera is exposing correctly for the overall unit/environment. If you exposed for the LEDs the rest of the exposure would be too dark. Going to guess there's no vellum between the LEDs and the meters like there is(?) between the LEDs and the dial, as well.
I notice the same thing when I take a phone snapshot for the What Are You Listening to Now thread. The strobe light on the TT gets overexposed because the phone exposes for the overall scene.
I'd guess the reason you don't SEE the hot spot is our eyes have a wider dynamic range than digital cameras. We see the LED as bright, but our eyes see the dark end lighter than a camera does.
If you were going to photograph your receiver and wanted to mitigate or possibly totally get rid of the hot spots you would:
• Tripod your camera
• Find the correct exposure for the LED via the shutter speed.*
• Use flash/es to light the rest of the scene.
*You would want an aperture small enough (size not #) to use a slower shutter speed. By slower I mean not too fast for your flash. On my camera it would have to be slower than 1/160th of a second.
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