Occasional shadow flutter in shot

[Topo]

On some of my footage I’m seeing a flutter, which appears to be coming from some sort of prop shadow. It’s not the issue where you can actually see a prop in the upper corner. This flutter is seen over the entire raster. It’s kind of like a light shadowy waviness, generated by the props. I believe I see it when I am going swiftly forward in a certain light from the sun. It’s tricky to evaluate what conditions are causing it, but those shots aren’t usable with the flutter.
Anyway...appreciate it if someone has experienced this and knows how to avoid it.

 

[SpinItUp]

footage or it doesn't happen
pulease
Welcome BTW (excuse my non politeness)

 

[Topo]

Ahh...yes, good advice...I’ll get a sample together when I have a chance.

 

[CanadaDrone]

Include your exposure settings as well - with that and footage it should be easy enough to tell what is going on.

 

[Meta4]

On some of my footage I’m seeing a flutter, which appears to be coming from some sort of prop shadow. It’s not the issue where you can actually see a prop in the upper corner. This flutter is seen over the entire raster. It’s kind of like a light shadowy waviness, generated by the props. I believe I see it when I am going swiftly forward in a certain light from the sun. It’s tricky to evaluate what conditions are causing it, but those shots aren’t usable with the flutter.
Anyway...appreciate it if someone has experienced this and knows how to avoid it.

The obvious way to prevent prop shadow is to avoid flying camera angles that allow the sun to shine through your props onto the lens

 

[kloogee]

As others have mentioned, the cause is from the shadows generated from the props when they are in a direct line between the sun and the camera lens. The first solution is probably quite obvious which is "just don't do that". Lol!

The second much less obvious solution is to use ND filters to bring your shutter speed down to match the "rule of 180" when it comes the relationship between shutter speed and the frame rate you are recording. Without the ND filters, the shutter speed is probably extremely fast and is able to catch the movement of the props in the shadows. If you slow the shutter speed down, then motion blur will effectively remove this as a problem.

I made a video about ND filters over a year ago and made a demonstration using a fan. The concept is very similar to what is seen with the fan. At a very high shutter speed, the fan looks very choppy. At a much slower shutter speed matching the rule of 180, the fan looks buttery smooth. It is around the 8:05 mark in the video where this demonstration starts.

 

[Topo]

Thanks everyone...here's a bit of one shot. I had exposure in auto. Kloogee, it sounds like you're quite familiar with this issue. Does my sample appear to display the issue you think it is? I guess I was flying in just the right direction to cause this... I'll check out your tutorial vid. Dropbox - FlickeryDickery.mp4.

 

[Topo]

As others have mentioned, the cause is from the shadows generated from the props when they are in a direct line between the sun and the camera lens. The first solution is probably quite obvious which is "just don't do that". Lol!

The second much less obvious solution is to use ND filters to bring your shutter speed down to match the "rule of 180" when it comes the relationship between shutter speed and the frame rate you are recording. Without the ND filters, the shutter speed is probably extremely fast and is able to catch the movement of the props in the shadows. If you slow the shutter speed down, then motion blur will effectively remove this as a problem.

I made a video about ND filters over a year ago and made a demonstration using a fan. The concept is very similar to what is seen with the fan. At a very high shutter speed, the fan looks very choppy. At a much slower shutter speed matching the rule of 180, the fan looks buttery smooth. It is around the 8:05 mark in the video where this demonstration starts.

Just watched your vid...excellent. Dumb question; if I use an ND filter, and leave my exposure in Auto, will the camera adjust appropriately? Or is it necessary to set exposure manually? A friend had just told me to look into a filter called Polar Pro...is that an ND, or just a polarizing filter? thanks

 

[kloogee]

Thanks everyone...here's a bit of one shot. I had exposure in auto. Kloogee, it sounds like you're quite familiar with this issue. Does my sample appear to display the issue you think it is? I guess I was flying in just the right direction to cause this... I'll check out your tutorial vid. Dropbox - FlickeryDickery.mp4.

Yes, that looks very much like what I expected to see. It does look like prop shadow from the sun to me.

 

[kloogee]

Just watched your vid...excellent. Dumb question; if I use an ND filter, and leave my exposure in Auto, will the camera adjust appropriately? Or is it necessary to set exposure manually? A friend had just told me to look into a filter called Polar Pro...is that an ND, or just a polarizing filter? thanks

Yes, you can definitely leave the camera in auto and it will adjust appropriately. By having an ND filter installed, it will limit the amount of light entering the camera and will slow the shutter speed down. I think most people think of PolarPro as the top of line (and most expensive) ND filters. Freewell also makes some great filters at a bit lower cost.

Good ND Filters won't affect the color of your picture at all, just will allow you to slow down your shutter speed to the lower amount of light entering the camera. Polarizing filters actually will affect the colors and depends upon the angle of the sun and the adjustment you make on the circular lens. The following article is a good start to describing ND vs. Polarizers. It isn't specific to drones, but a camera is a camera regardless of if you are holding it or flying it with a drone.

https://www.adorama.com/alc/nd-filter-vs-polarizer-what%e2%80%99s-the-difference

ETA: PolarPro makes a great phone app that helps you choose which filter to use in a given situation: PolarPro | App

 

[Topo]

Yes, you can definitely leave the camera in auto and it will adjust appropriately. By having an ND filter installed, it will limit the amount of light entering the camera and will slow the shutter speed down. I think most people think of PolarPro as the top of line (and most expensive) ND filters. Freewell also makes some great filters at a bit lower cost.

Good ND Filters won't affect the color of your picture at all, just will allow you to slow down your shutter speed to the lower amount of light entering the camera. Polarizing filters actually will affect the colors and depends upon the angle of the sun and the adjustment you make on the circular lens. The following article is a good start to describing ND vs. Polarizers. It isn't specific to drones, but a camera is a camera regardless of if you are holding it or flying it with a drone.

https://www.adorama.com/alc/nd-filter-vs-polarizer-what%e2%80%99s-the-difference

ETA: PolarPro makes a great phone app that helps you choose which filter to use in a given situation: PolarPro | App

I've ordered just 3 inexpensive ND's to start. Another dji drone owner friend and myself are trying to understand shutter speed as it relates to video. With stills, it's quite common sense, as a slower shutter speed can give you the blurred water effect, shooting a stream or falls. I guess it must be similar, since you've described filter "motion blur" introduced with slower shutter speeds, in video.

 

[kloogee]

I've ordered just 3 inexpensive ND's to start. Another dji drone owner friend and myself are trying to understand shutter speed as it relates to video. With stills, it's quite common sense, as a slower shutter speed can give you the blurred water effect, shooting a stream or falls. I guess it must be similar, since you've described filter "motion blur" introduced with slower shutter speeds, in video.

Yep, because of the way the brain and eye work together, it expects to see a certain amount of motion blur in each individual image that makes up the video. Video after all is just a quick series of individual pictures recorded/shown at a rate of 24/30/60 images per second. If the amount of movement between frames is larger than the amount of motion blur associated with that frame, then the brain starts disconnecting them and sees them in a staccato sequence rather than a smooth sequence. If interested in learning more, google "video rule of 180".