Whats causing this?
Dec 5, 2021 11:55:38 #
CHG_CANON wrote:
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.
I forgive the camera 🤗
Dec 5, 2021 11:57:26 #
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. Any ideas? These aren't flickering lights.
The Ghost of Christmas Present
Dec 5, 2021 12:03:11 #
How'd we get from Christmas lights flickering to frame rates on TVs??? 
Dec 5, 2021 12:06:32 #
Well I think the OP isn't curious but I am. So if I am the OP I would try to plug one of the strings differently to see if the strings are on and off the same time. It appears that as is one of the strings is on while the other is off. I think the plug isn't polarized so that you can plug them in either way.
Dec 5, 2021 12:08:45 #
BebuLamar wrote:
Well I think the OP isn't curious but I am. So if I am the OP I would try to plug one of the strings differently to see if the strings are on and off the same time. It appears that as is one of the strings is on while the other is off. I think the plug isn't polarized so that you can plug them in either way.
Nothing to do with plug polarization or orientation.
Dec 5, 2021 12:28:17 #
BebuLamar wrote:
Well I think the OP isn't curious but I am. So if I am the OP I would try to plug one of the strings differently to see if the strings are on and off the same time. It appears that as is one of the strings is on while the other is off. I think the plug isn't polarized so that you can plug them in either way.
It's only one string BebuLamar.
Dec 5, 2021 12:34:39 #
Ava'sPapa wrote:
It's only one string BebuLamar.
OK if it's only 1 string so internally it's wired so that half of the lights would lit up for 1/2 the cycle and the other half lit up for the other half of the cycle. It would make perfect sense for doing so.
If the entire string would light up or off then the polarity of the plug makes the different.
Dec 5, 2021 12:38:47 #
BebuLamar wrote:
...
If the entire string would light up or off then the polarity of the plug makes the different.
If the entire string would light up or off then the polarity of the plug makes the different.
No, it would look the same, only phase shifted 1/2 a cycle.
Dec 5, 2021 12:41:29 #
Longshadow wrote:
No, it would look the same, only phase shifted 1/2 a cycle.
But if you have 2 strings that each only light up for half of the cycle. Changing the polarity of one would make them both on or off at the same time or alternate.
Dec 5, 2021 12:47:40 #
BebuLamar wrote:
But if you have 2 strings that each only light up for half of the cycle. Changing the polarity of one would make them both on or off at the same time or alternate.
Ahhhh. Key operator: TWO STRINGS.....
I was referring to one string.
Then again, it depends in the wiring to be the same in both strings.
If the Anode goes to the other plug in one string, to get them in sync, one would have to be plugged in backwards.
But of course it would only apply to certain shutter speeds, not the human eye.
Dec 5, 2021 13:29:19 #
Longshadow wrote:
How'd we get from Christmas lights flickering to frame rates on TVs???
AC power frequency is directly related to both.
Dec 5, 2021 13:55:10 #
Another example: Fluorescent lights.
The fluorescent bulbs flicker at a 120 Hz rate (twice the 60 Hz line) because the power flows both ways through the discharge in the bulb. You get a pulse of UV light from the discharge which activates the phosphor coating on the bulb to produce the visible light. About 10 years ago I took a series of shots of a fluorescent bulb at 1/1000 second. You can see the different colors where the UV pulse is activating the phosphor and where the UV pulse has dissipated and the phosphor is changing color. The bulbs are vertical in the image and the shutter travels along the length of the bulb giving an exposure that shows different times along the tube. The typical shutter takes about 1/250 second to travel across the image so you see about half the 1/120 second lighting of the bulb. The different colors are in different locations because there is no synchronization between the shutter and the line frequency.
This also shows why fluorescent lighting can present problems for short exposures, particularly in the white balance of the resulting image.
The fluorescent bulbs flicker at a 120 Hz rate (twice the 60 Hz line) because the power flows both ways through the discharge in the bulb. You get a pulse of UV light from the discharge which activates the phosphor coating on the bulb to produce the visible light. About 10 years ago I took a series of shots of a fluorescent bulb at 1/1000 second. You can see the different colors where the UV pulse is activating the phosphor and where the UV pulse has dissipated and the phosphor is changing color. The bulbs are vertical in the image and the shutter travels along the length of the bulb giving an exposure that shows different times along the tube. The typical shutter takes about 1/250 second to travel across the image so you see about half the 1/120 second lighting of the bulb. The different colors are in different locations because there is no synchronization between the shutter and the line frequency.
This also shows why fluorescent lighting can present problems for short exposures, particularly in the white balance of the resulting image.
Dec 5, 2021 14:08:08 #
larryepage
Loc: North Texas area
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. Any ideas? These aren't flickering lights.
So unplug the string that is out of synch, flip the plug 180 degrees, and replug it. Then turn on anti flicker and try again. All should be good. Not an uncommon problem, and not a biggie to fix.
Dec 5, 2021 14:28:18 #
burkphoto wrote:
AC power frequency is directly related to both.
As well as digital clocks.
Still off on a tangent from the original question. Lets explain everything affected by line frequency, it's related.
Dec 5, 2021 15:32:09 #
larryepage wrote:
So unplug the string that is out of synch, flip the plug 180 degrees, and replug it. Then turn on anti flicker and try again. All should be good. Not an uncommon problem, and not a biggie to fix.
Just looked up anti-flicker. Apparently Canon has it on some cameras. It works by sensing flicker and delaying a shutter release to a specific part of the flicker phase. It works at 100 or 120 Hz to correspond to common line frequencies. None of my old bodies has it (they're all Nikon). https://www.the-digital-picture.com/Canon-Cameras/Anti-Flicker-Mode.aspx
If that is what it does, then depending on where in the image it is sensing the flicker, what you will get is all your shots with the same portion of the string on in every shot. It's not likely that LED lights will overlap on an AC driven string. No matter which way you have it plugged in. (And it assumes that your light string does not have a polarized plug, which is common on many two-prong plugs these days [the neutral prong is slightly wider than the hot prong]). PS: the referenced article says that if flicker is detected, an indication appears in the viewfinder.
But if your R6 has anti-flicker, then it's an easy experiment to perform. Post the results, please.
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