On my way on experimenting with time-lapse, I'm facing a flickering of brightness after I stitch the images together and make a video. I understand that if I use Av mode while I'm taking the pictures, per each shot, the camera will recalculate the exposure and that might result in different shutter speeds and in turn, this will result in the flicker when the images are made into a video.
But in this case, I'm using the manual mode and I'm setting the aperture, time and ISO manually. There's no readjustment left for the camera and supposedly all the shots are identical - parameter-wise (and they are, I checked). But still, when I stitch the images into one video file, it flickers. Why is that?
BTW, I'm not interested in how to fix this issue using a software. I'm just curious if this is expected and if there's a reasonable explanation behind it.
I'm using a Canon 6D. It was on a tripod for half an hour and I took 360 shots with the following settings:
- Aperture: F22
- Shutter speed: 1/5
- ISO: 200
- Lens: Canon EF 24-105mm 1:4 L IS USM
- With two ND filters: 8ND and a 4ND (I was shooting the clouds on bright daylight)
Here's my video on youtube. The quality is lowered but I believe you can see the blue sky flickering.
I just remembered that I have another test with the same exact problem. In this case, I was indoors and in a shade. I've had almost the same settings as before except my shutter speed was 1/3s. Even though I'm not 100% sure but I think I've had three ND filters this time (2ND + 4ND + 8ND).
Per suggestions in the answer, I shot another time-lapse. This time, the camera was in shade completely and with a hood on. The settings are like before (1/5s and with two ND filters) and the flicking is still there. Next, I'll test with higher shutter speed and without ND filters (but I think the result will be the same). Stay tuned (I have to wait for another partly cloudy day).
As the only test left (at this point), I conducted another failed test. This time I shot in RAW format and set the white balance in post-production using Darktable. But as you can see the flickering is still there.
On top of that, as part of the new knowledge that I've gained, I extracted the exposure value out of the exif data (called
MeasuredEV) and plotted it in the following chart:
My eyes are not exact enough to say if the flickerings are actually matching the spikes or not. But I assume so. To be complete, my camera settings are; shutter speeds 1.6", ISO 50, and aperture F22. Also, I had three ND2, ND4, and ND8 filters mounted on the lens.