I can see flicker in some LED lighting in the corner of my eyes, using the rods in the irises of my eye, when I can’t see it using the cones in the retina. Stick the light in the middle of my vision, and the flicker vanishes.
Wikipedia says that the cones are more time-sensitive than the rods, which isn’t what I’d expect if that were the case.
Different points in the visual system have very different critical flicker fusion rate (CFF) sensitivities; the overall threshold frequency for perception cannot exceed the slowest of these for a given modulation amplitude. Each cell type integrates signals differently. For example, rod photoreceptor cells, which are exquisitely sensitive and capable of single-photon detection, are very sluggish, with time constants in mammals of about 200 ms. Cones, in contrast, while having much lower intensity sensitivity, have much better time resolution than rods do. For both rod- and cone-mediated vision, the fusion frequency increases as a function of illumination intensity, until it reaches a plateau corresponding to the maximal time resolution for each type of vision. The maximal fusion frequency for rod-mediated vision reaches a plateau at about 15 hertz (Hz), whereas cones reach a plateau, observable only at very high illumination intensities, of about 60 Hz.[3][4]
Passing an open hand with fingers extended in front of the light tends to make any flicker more visible, as it makes the moving fingers “judder”, as with a strobe light.
The flicker fusion threshold does not prevent indirect detection of a high frame rate, such as the phantom array effect or wagon-wheel effect, as human-visible side effects of a finite frame rate were still seen on an experimental 480 Hz display.[6]
With the rods of the eye. Your eye doesn’t consist entirely of rods.
The Wikipedia article says that your cones should be more-sensitive to flashing at higher frequencies than the rods. The rods are what are what pick up light when you’re viewing something through the corner of your eye. What I experience with these bulbs is the opposite of what I’d expect from that: flashing is noticeable and annoying when viewed in my peripheral vision, but gone (well, or on the edge of noticeability) when in the center of my vision.
EDIT: Well, to be fair, I guess I don’t actually know that they don’t have some sort of power control circuitry, haven’t pulled one apart, so I guess I shouldn’t say that they’re 60 Hz. But unlike typical LED bulbs, they’re narrow; these corncob bulbs don’t have the bulge for space for an electronic ballast. If they don’t have the ballast, I’d be expecting them to run off the wall power directly.
I wonder if I can go dig up a datasheet somewhere.
EDIT2: None of the technical material talks about any frequency of the bulb, but you might be right. There’s one other thing power-control thing that you can stick in a bulb that might take up space, and that’s a dimmable power supply. Like, if the wall power voltage drops, those will detect and reduce brightness. This one’s non-dimmable. Maybe that’s where the bulge at the base of LED bulbs comes from — dimmer electronics — and there’s enough space to fit non-dimmable electronics up inside the body of the bulb.
I can see flicker in some LED lighting in the corner of my eyes, using the rods in the irises of my eye, when I can’t see it using the cones in the retina. Stick the light in the middle of my vision, and the flicker vanishes.
Wikipedia says that the cones are more time-sensitive than the rods, which isn’t what I’d expect if that were the case.
https://en.wikipedia.org/wiki/Flicker_fusion_threshold
Passing an open hand with fingers extended in front of the light tends to make any flicker more visible, as it makes the moving fingers “judder”, as with a strobe light.
It’s totally normal to perceive flickering at 60Hz
According to the above Wikipedia article, I don’t believe it should be possible to see it with the rods at 60 Hz.
Tell that to my eyes lol. It’s easy to see flickering of 60Hz on a CRT displaying a white screen.
With the rods of the eye. Your eye doesn’t consist entirely of rods.
The Wikipedia article says that your cones should be more-sensitive to flashing at higher frequencies than the rods. The rods are what are what pick up light when you’re viewing something through the corner of your eye. What I experience with these bulbs is the opposite of what I’d expect from that: flashing is noticeable and annoying when viewed in my peripheral vision, but gone (well, or on the edge of noticeability) when in the center of my vision.
EDIT: Well, to be fair, I guess I don’t actually know that they don’t have some sort of power control circuitry, haven’t pulled one apart, so I guess I shouldn’t say that they’re 60 Hz. But unlike typical LED bulbs, they’re narrow; these corncob bulbs don’t have the bulge for space for an electronic ballast. If they don’t have the ballast, I’d be expecting them to run off the wall power directly.
I wonder if I can go dig up a datasheet somewhere.
EDIT2: None of the technical material talks about any frequency of the bulb, but you might be right. There’s one other thing power-control thing that you can stick in a bulb that might take up space, and that’s a dimmable power supply. Like, if the wall power voltage drops, those will detect and reduce brightness. This one’s non-dimmable. Maybe that’s where the bulge at the base of LED bulbs comes from — dimmer electronics — and there’s enough space to fit non-dimmable electronics up inside the body of the bulb.