question about 6D burst mode

hi all
i was playing around with a friend's 6D at a NYE party. it was coupled with a 50/1.4, and a joy to use.

at one point, i was trying to take burst shots of some party silliness with a fast shutter to capture people jumping in the air. i noticed that the shutter wasnt rolling through completely - ie in a burst of 5 exposures, the 2nd or 3rd pic would have one half of the image darkened.

everything was lit with ambient light and i wasnt using a flash, so i dont know if this is something to do with the 1/180 sync speed. just found it strange that it the shutter wouldnt roll through fast enough across multiple exposures.

any thoughts?

And no flash was mounted? A half dark image is usually a flash sync issue. I'll have to try that with mine.

Hmmm, that doesn't sound good and it couldn't have anything to do with the sync speed if you weren't using flash.

hmm, hope i dont have to break the news to my friend that something may be wrong with his 6d. i will try to put up some pics later

Was the ambient light from a cycling source like florescent lights?

And you mean darkened not totally black correct?

yup, darkened

the light source was pretty much all from xmas lights strung up all around the room, and some paper lantern lamps (not sure what kind of bulbs). i doubt the light source type was the issue, as other pictures all came out fine, the issue was just when i was burst shooting

ekinnyc wrote in post #16571782
yup, darkened

the light source was pretty much all from xmas lights strung up all around the room, and some paper lantern lamps (not sure what kind of bulbs). i doubt the light source type was the issue, as other pictures all came out fine, the issue was just when i was burst shooting

If you shortened your shutter speeds in order to do the bursts then you open youself up to cycling by the various lights, which sounds like the culprit here. The cycling only shows up when your shutter speed is less than the cycle of the lights.

wouldnt it manifest differently than a half light/half dark image? ie. everything in the scene would be darker if i hit the shot mid-cycle

gonzogolf wrote in post #16571792
If you shortened your shutter speeds in order to do the bursts then you open yourself up to cycling by the various lights, which sounds like the culprit here. The cycling only shows up when your shutter speed is less than the cycle of the lights.

That is my guess as well. If you have more than one light source, you can capture one of the light sources in a different cycle and it will be dark only in the area it is illuminating.

Incandescent bulbs don't do this but any kind of fluorescent or sodium bulb will. I believe some LED lighting can also do this.

http://electronics.sta​ckexchange.com …r-like-fluorescent-lights

ekinnyc wrote in post #16571796
wouldnt it manifest differently than a half light/half dark image? ie. everything in the scene would be darker if i hit the shot mid-cycle

Nope. You can get very unusual patterns with a dark and oddly colored banding across a portion of the the frame. Keep in mind the way your shutter works, at speeds shorter than max sync speed (1/160 on the 6D ) the second curtain starts to close before the entire shutter is exposed to light. That means the effect may only appear in a portion of the frame.

ekinnyc wrote in post #16571796
wouldnt it manifest differently than a half light/half dark image? ie. everything in the scene would be darker if i hit the shot mid-cycle

No, because when the shutter speed is faster than the sync speed of the camera, the entire sensor is not exposed at the same time. At very high shutter speeds like 1/4000 the exposure is made by a slit opening that passes across the sensor, for example.

So at a shutter speed of 1/400 or so, there will be a time where half the sensor is exposed and half is under the closing curtain.

just went thru the pics, they were all ISO12800, f/1.4, and 1/400 or 1/800

here is an example

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ekinnyc wrote in post #16571782
i doubt the light source type was the issue, as other pictures all came out fine, the issue was just when i was burst shooting

ekinnyc wrote in post #16578449
just went thru the pics, they were all ISO12800, f/1.4, and 1/400 or 1/800

here is an example ...

What was the shutter speed on the images that were OK? I'm picking it was 1/120, 1/60, or 1/30 (or 1/40 if that is an option).

here is one with the same settings ISO12800 f1.4 1/400
for the most part it looks good though you could see the shutter creeping off to the right as it is just slightly dark

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That looks like typical fluorescent lighting cycling to me.