A6300 Shadow Color Shift/Flickering Bug

[jbproflm]

Hey guys, I've been testing my A6300 without any major issues so far until I started noticing something very strange. I'll do my best to describe it. When shooting with either ITU709(800%), S-Log2 or S-Log 3 Picture Profile gammas, there seems to be some kind of odd color shifting/flickering that occurs in the shadow regions of a shot whenever a brighter light source enters or goes off screen. Like if I'm shooting a living room or kitchen interior and I pan into or away from a bright window or a lamp, the shadow areas will suddenly start flickering and shifting colors. It looks like some kind of exposure detection is triggering the effect, but I've turned off all of the camera's auto settings and it still occurs. Here's a short clip showing what I'm talking about:

 

 

https://www.youtube.com/watch?v=t8SZBe5HaZ4

 

 

I've tested this with different lenses, all video formats and the main configuration that seems to trigger this color shift/flickering is using either ITU709 800%, S-Log2 or S-Log 3 gammas in 4K XAVC S mode and sometimes in HD XAVC S mode. I managed to see this flickering in Cine2 gamma as well, but not as consistently as with the other 3 gammas. I've tried using auto/manual/custom white balance, in all still/video dial modes, all Picture Profile options, manual/auto exposure/shutter, all auto, all manual settings and I consistently keep seeing the same bug as long as one of those gammas are selected. My camera firmware version is Ver. 1.00.

 

One other strange observation I've noticed is that whenever I change ISOs with these gammas, I will see a similar type of flickering occur a few moments after switching to a new ISO. I'm not sure if this is somehow related to what's causing this. Can any of you A6300 owners try this out and see if you get similar results? I'm really curious to know if I'm the only one having this issue. Thanks.

 

 

[jbproflm]

Anyone else seeing this? I've tested every configuration ad-nauseum and this bug will not go away no matter what the settings are as long as those main 3 gammas are selected. (ITU709(800%),S-Log2, S-Log3) though I have also seen it occur even in Cine2 a bit. As you can see from the video, the flickering occurs in a stepping up/down type of pattern.

 

My best technical guess of what may be occurring is either some type of auto exposure/scene detection is pushing/pulling the lowlights in realtime based on how bright/dark the scene becomes. It almost appears similar to what the DRO Dynamic Range Optimizer does, but this option is disabled and greyed out whenever Picture Profiles are being used. What is strange is that the shadow colors are also shifting cooler/warmer, like if AWB was turned on but its definitely switched off in the camera settings. 

 

There must be some kind of unchangeable automatic setting being activated in Movie Mode whenever these gammas are being selected. Even without a lens attached and turning the camera with the body cap on, I can see this flickering effect while changing ISOs. (For example, changing to PP3 and switching the gamma to ITU709(800%), the flicker is very noticeable switching through ISOs when the body cap is on. Some ISOs will show a stronger stepping effect than others. I don't know if this ISO switching flicker effect is related to the main bug I mentioned, but its just an observation I've made that also occurs when these gammas are selected. If this was something that occurred all the time no matter what the settings were I would think I had a defective camera, but the fact that its only occurring under specific Picture Profile gamma settings leads me to believe this is some kind of firmware issue. Does anyone else want to try it and see if your camera does this too?

 

 

[jbproflm]

After very exhaustive testing, I've concluded that this color shift/flickering is in fact occurring under ANY selected gamma and even with Picture Profiles turned OFF. The main 3 gammas previously mentioned just happen to be more SENSITIVE about it than all the others, as well as the main 3 with the ISO switching flicker effect.

 

There is definitely some type of automatic setting enabled during Movie Recording (or perhaps all the time?) that is detecting exposure and/or white balance and is automatically COMPENSATING in realtime by either pulling/pushing exposure or shifting the color balance of the shadows/lowlights in a stepping up/down pattern whenever a bright light source is entering and exiting a shot. I have turned off EVERY selectable automatic option in the menus, switched every possible mode to MANUAL including White Balance, made sure DRO/Auto HDR is OFF, but this is still occurring no matter what. 

 

 

I was planning to use this camera to shoot real estate videos, but if I keep getting this shadow color shift/flickering effect happening every time I'm panning over to any interior windows/lights, I'm going to end up with a lot of flickering footage. Unfortunately my camera is now past the return/exchange period so at this point I need to find out if I have a defective camera or not. The only real way to find out is by hearing back from other owners to see if this is in fact something that is occurring with all A6300s. I'd really appreciate anyone else willing to try this out to confirm whether or not it just happens with my camera. Thanks.

[CTMB]

@jbproflm,

 

I noticed that in your test video your lamp has what looks like a LED bulb. I was running a test in one of bedrooms with LED lighting and had a similar problem. Have you tried using another light source?

[Golem]

@jbproflm,

 

I noticed that in your test video your lamp has what looks like a LED bulb.

I was running a test in one of bedrooms with LED lighting and had a similar

problem. Have you tried using another light source?

  

But the problem can be seen even with the body cap in place. 

  

I don't fully understand, but one thing that struck me is changing

ISOs. I thought the profiles were for use at base ISO without the

added gain of a raised ISO, cuz the profiles are designed to allow

pumping up the image in post instead of while recording.

  

The shadow noise looks like excessive gain. BTW what tells you

it's an LED light ? I tried to find some hint, but I'm not finding it.  

  

If the above has any merit at all, then the effect should disappear

at the base ISO. As I said, I don't fully understand. I'm not a video

geek in the least. 

[jbproflm]

Part of my testing included testing this under different lighting scenarios. I've since had this effect occur even in daylight by just filming a kitchen/living room interior and panning towards/away from a sunlit window. I've even tried it outdoors in a sunlit/shade scenario. There is definitely some kind of automatic exposure scene detection that is triggering the effect based on the scene's contrast between bright and dark levels as it seems to be triggered in a noticeable stepping up/down pattern.

[Golem]

Again I'm no video geek but my best understanding of

video is that ... crudely explained ... you are  basically

recording the viewing image. If that is a semi-accurate

ideation of digital video, then maybe you are shooting

with the "constant viewing brightness" engaged, which

means you selected "Effect Preview OFF". Perhaps try

filming with Effect Preview ON ? I realize that with the

gamma contour you've chosen this may be difficult but

even if it's not a practical approach to filming, it might

serve as a diagnostic tool. 

  

I might be a prime example of "a little knowledge is a

dangerous thing", but sometimes it leads to "thinking

outside the box". Seems like the experts thinking "in

the box" haven't solved it so far, so what-the-hey .... 

  

Acoarst it would be a drag if viewing in Effect Preview

defeats the "exposure detection" bugaboo but results

in difficult or impossible viewing while filming. 

  

Afterthought: Can it be that the gamma you've chosen

is "trying to open up" the deep shadows, but where the

available supply of photons is not adequate to do that

then it just makes a whole bunch of gain noise ?

[DanBoey]

I just received my a6300 today and am keen to use it for video mostly as well. I can definitely confirm that this colour flickering has also happened to me today while i was in my kitchen and was testing out some panning shots. Hopefully will be addressed in an upcoming firmware update? Id hate for this to be overlooked.