LRTimelapse Forum

I've been shooting time lapse with my Sony Alpha 77 now for three years. Wow, time does fly! During that period, I've occasionally had issues with dark areas of an image: when I lift these using the shadows control in LR I sometimes see different and random hues in that area of the image on each frame in a sequence. This results in a very noticeable colour flicker, and because it doesn't affect overall brightness it can't be corrected using LRT's visual deflicker (which is to be expected, of course).

I have never found a way to correct this problem, and I usually end up keeping the shadows almost black in order to avoid the effect becoming visible. Sometimes I even use one of the grad filters to desaturate that part of the image, where possible. Of course the best solution would be to shoot with enough exposure to avoid the black end of the histogram... but of course, often that's not practical because there is bright sky in the shot and I'm trying to avoid blown highlights.

Then, today, I was watching some time lapse shooting advice (from Ian Norman at Lonely Speck - https://www.youtube.com/watch?v=ir7gBv7FRcs ), and noticed that Ian (who is using a Sony a6000, I think) advises to set white balance to something other than AWB. I suddenly wondered whether this was the problem! I had never thought about it before, because I always shoot RAW, so I assumed that AWB would not affect the images. However, I can imagine that perhaps there is some sort of 'compensatory' data value stored alongside the raw data, which LR may use to correct the colours on each shot, despite having RAW files. This seems unlikely, but it's one possible explanation.

An alternative explanation is that the sensor data is simply too dark to have sufficient resolution, and therefore the colours are being amplified from a small set of values, resulting in poor colour fidelity.

I wanted to mention the issue in case others have investigated it before and discovered anything relating to using AWB in RAW mode. If you have any advice, I'd be grateful to receive it.

Thanks, and happy shooting!

Did you have AWB set on the Keyframes? Normally LRTimelapse sets a default WB value when initializing, and then normally you just set the WB manually when editing the keyframes. However, if you set the WB back to "As Shot" in Lightroom, of course when developing, it will evaluate the values that the Camera wrote into the exif data - and this might be different for each image.

Thanks Gunther, that's worth knowing! I'm pretty sure I never touch that setting though. I just checked one of the affected sequences to make sure, and all the key frames are set to Custom.

I think I'm going to do some experiments with my camera to try to understand more deeply how it behaves. It may be that the actual colour information somehow depends on the AWB, even in RAW mode, which would then mean that there is no easy way to fix it in post-processing. However, I'm beginning to think that the other explanation may be more plausible: if pixels are dark enough, the hue information is degraded when the luminance is increased later on in post. I'm not sure whether actual pixel data in a RAW is floating point (I suspect not), but even if it is, then I assume the problem could still happen because of the effectively-reduced bit depth of the actual signal from the sensor.

The best solution may be to use a camera that handles low light better. That's on my wish list

I've experienced that kind of color flicker in very dark sequences (for example Milky Way) too with the earlier Sony sensors (Nikon D7000 for example). And I always shoot with fixed WB. It's a pita and quite impossible to correct, at least, if you need the colors. I don't think it has to do with the WB setting.
Make your experiments - but my recommendation would be to change to a better sensor.

That's bad news, but thanks for posting the info! I bought my a77 before I became interested in time lapse, and for a long time I've realised it wasn't the best choice. Later this year I may have budget for new gear. Out of interest, do you still recommend Nikon D750, or are there better choices around now?