Whats causing this? I was playing around with my new RF 70-200 the other night, on my R6 and I noticed this oddity. The first two photos were shot in Program (maybe auto) and the last...

Ava'sPapa Loc: Cheshire, Ct.

I was playing around with my new RF 70-200 the other night, on my R6 and I noticed this oddity. The first two photos were shot in Program (maybe auto) and the last two were shot in aperture priority. I'm wondering why all of the lights weren't illuminated in the photo ( when in fact they were all lit ) in Program mode and they showed up fine (all lit) in AP mode. Any ideas? These aren't flickering lights.

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Longshadow Loc: Audubon, PA, United States

Need picture.

But I'll guess if they are LED lights and on a duty cycle (not constantly on), the shutter speed caught some LEDs on the off cycle. The duty cycle is fast enough that the image retention in our eyes sees them as constantly on.
A different shutter speed may have been used in AP mode. Which I'll guess to be slower.

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

Ava'sPapa wrote:

I was playing around with my new RF 70-200 the other night, on my R6 and I noticed this oddity. The first two photos were shot in Program (maybe auto) and the last two were shot in aperture priority. I'm wondering why all of the lights weren't illuminated in the photo ( when in fact they were all lit ) in Program mode and they showed up fine (all lit) in AP mode.

https://www.canon.com.hk/cpx/en/technical/pa_Anti-Flicker_Shooting.html

Ava'sPapa Loc: Cheshire, Ct.

Longshadow wrote:

Need picture.

But I'll guess if they are LED lights and on a duty cycle (not constantly on), the shutter speed caught some LEDs on the off cycle. The duty cycle is fast enough that the image retention in our eyes sees them as constantly on.
A different shutter speed may have been used in AP mode. Which I'll guess to be slower.

Constantly on which is why I'm puzzled.

Ava'sPapa Loc: Cheshire, Ct.

Gene51 wrote:

https://www.canon.com.hk/cpx/en/technical/pa_Anti-Flicker_Shooting.html

I just scrolled down. Thank you for the info. Not flickering lights BTW.

BebuLamar

Ava'sPapa wrote:

Constantly on which is why I'm puzzled.

I think you have 2 strings of lights and although to your eyes they are constantly on but they are only on half of the time.

CHG_CANON Loc: the Windy City

I didn't go through every last possible difference, but the difference in the metering mode in Aperture Priority likely caused the camera to expose the same scene differently.

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cyclespeed Loc: Calgary, Alberta Canada

I am for LED lights as the use. They change on / off so fast our eyes don't detect it but a short SS does. I had to the close to a dozen pics of our tree lit with LEDs before luck allowed all to be on.

DirtFarmer Loc: Escaped from the NYC area, back to MA

BebuLamar wrote:

I think you have 2 strings of lights and although to your eyes they are constantly on but they are only on half of the time.

LED lights running on AC. An LED only lights up when current is flowing in one direction. When it flows the other direction they are dark. This happens 60 times per second so your eyes will not see the flickering. The flicker threshold varies with individuals but is generally below 30/second, which is why that is the movie frame rate.

Use a slower shutter speed.

Tomfl101 Loc: Mount Airy, MD

I think Gene is correct. Turn on Anti Flicker and I’ll bet the problem goes away. On my R5 it’s on the red menu section 2. The only reason to turn off anti-flicker is that it slows down drive speed while the shutter pauses between exposures in order to capture full illumination of flickering lights. I usually leave it on full time. Stadium and arena lighting is where the problem is most often an issue. Mirrorless cameras seem to be more susceptible to the problem.

BebuLamar

DirtFarmer wrote:

LED lights running on AC. An LED only lights up when current is flowing in one direction. When it flows the other direction they are dark. This happens 60 times per second so your eyes will not see the flickering. The flicker threshold varies with individuals but is generally below 30/second, which is why that is the movie frame rate.

Use a slower shutter speed.

You can make the LED stays on all the time too but they are cheap so they use only half wave rectifier.

jeep_daddy Loc: Prescott AZ

DirtFarmer wrote:

LED lights running on AC. An LED only lights up when current is flowing in one direction. When it flows the other direction they are dark. This happens 60 times per second so your eyes will not see the flickering. The flicker threshold varies with individuals but is generally below 30/second, which is why that is the movie frame rate.

Use a slower shutter speed.

Brian in Whitby Loc: Whitby, Ontario, Canada

Diodes, including the light emitting diodes, LEDs, only allow electrical current to pass through them in one direction. Since the lights are using 60 Hz AC, the electricity travels first in one direction and then I the opposite direction. This happens 60 times each second. The result is the LED switches off and on 60 times a second. At shutter speeds faster than 1/60 s, the photo is taken when one of the lights is off. The work around is to use a shutter speed of 1/30 s so you catch both lights on during the exposure.
There are ways of manufacturing LED light bulbs that do not behave this way by using a full wave rectified circuit to change the AC into DC. but it would increase the cost of the bulb and is probably not worth it for holiday lighting.
I wonder is the same thing happens with LEDs used for general lighting? The same thing would happen at least some of the time, the light would be off when you press the shutter.

frankraney Loc: Clovis, Ca.

Ava'sPapa wrote:

Constantly on which is why I'm puzzled.

AC cycles on and off, 60 times a second. That's too fast for your eyes to see, but the camera can. Light talk twinkle (on and off so you can see it) are made different, and labeled as such.

Longshadow Loc: Audubon, PA, United States

Brian in Whitby wrote:

Diodes including the light emitting diodes, LEDs o... (show quote)

If they used a bridge rectifier for the lights the lights would be on for the complete cycle, not half of it. But that would add to the cost of the lights, with no "visible" benefit to the viewer.