Flickering in Backlight

[Lister]

Shooting in backlight can apparently cause flickering only visible when the lens is pointing at the sun. Anybody else seeing these effects?

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[Lister]

Nearly a hundred views and nobody else is seeing this effect? Maybe my hardware is suspect.

After inspecting the prop circles and the gimbal position, I find it hard to see how the props could ever shadow the lens.

 

[Kilrah]

Yup, that would be the props, pretty common on all models.

 

[scro]

The mini 3 camera basically can't see the props at any point throughout the full gimbal range of motion, and certainly not in fairly steady flight in good conditions. Also, any shadows cast by the props can only pass across the camera when the light (ie sun) is a bit above the horizon and well round to either side relative to the drone body. In flight the body tilts and this affects where prop shadows would fall, but in anything but the most extreme of cases the direction of the light relative to the camera would be so far out of view that it the camera wouldn't see or be affected by prop shadows.

Many other DJI drones had the props much closer to the camera's field of view and in the right conditions the camera could actually see the props dip into view.

The flickering in the sample video is occurring when the sun is at such an angle that shadows from the props would not pass over or even nearly over the camera. The particular flickering observed is most likely caused by something else, potentially linked to the very fast shutter speed. In auto exposure the shutter speed would typically increase the more the camera is pointed towards the sun.

 

[Kilrah]

The sun does not need to hit the camera within the field of view, it'll still make some glare from internal reflections even if way out. If that gets to it through the props you'll see flickering like this.
Especially if the camera lens has some dust/dirt on it, so you might want to check that.

 

[scro]

The sun would have to be out of the camera's field of view for shadows from the props to pass over the camera. From a few crude measurements the sun would need to be more than 60deg off to the left or right for prop shadows to get to the camera. In the sample video it might just be far enough around to the left to get prop shadows, but then it also needs to be fairly low - nearly on the horizon.

 

[Lister]

Thanks for all the replies.

scro is correct and my initial estimation was wrong. An inspection of the aircraft shows that the props can never shadow the lens unless the sun is on the horizon or the aircraft is in an extreme and unusual attitude. On neither of those two shots do those conditions apply. They may be able to reflect light into the lens, however.

I did some more tests and I can see that the Mini 3 lens is quite susceptible to internal reflections. The combination of high shutter speed and the particular sun angle seems to reveal this.

I was unable to return to that location at the same time of day. I will attempt to do so tomorrow. If I can replicate the flickering, it may help to track down the cause.

 

[Lister]

I've been unable to reproduce the flickering for now. The sun is mostly obscured by wildfire smoke.

 

[Siam]

Thanks for all the replies.

scro is correct and my initial estimation was wrong. An inspection of the aircraft shows that the props can never shadow the lens unless the sun is on the horizon or the aircraft is in an extreme and unusual attitude. On neither of those two shots do those conditions apply. They may be able to reflect light into the lens, however.

I did some more tests and I can see that the Mini 3 lens is quite susceptible to internal reflections. The combination of high shutter speed and the particular sun angle seems to reveal this.

I was unable to return to that location at the same time of day. I will attempt to do so tomorrow. If I can replicate the flickering, it may help to track down the cause.

To really replicate the situation, wouldn't you want to return a few minutes later since the movement of the earth and sun changes every day (1 minute or so).