Video Cameras

[chipallen]

What experience has the group had with video cameras? I have been using a GoPro HD, but continue to have problems with "waves" in the playback. According to the GoPro Support website, this is probably vibration related.

One of the group has also used the HD170 from Drift Innovation. The videos look good, but it's more expensive.

Need to find a nice combination of ease of use, quality video, and cost, recognizing that cost and quality are directly proportional; quality gets better, price goes up!

Comments?

Thank you,

[turbopilot]

Drift HD170 will wave depending on RPM setting. In my aircraft best video is at lower power settings.

Here is one from the cockpit with audio:

[Centmont]

There are currently two very active threads on Supercub.org and BackCountry Flyers on this very subject. Much experience and ways around the prop issue... Ralph

[turbopilot]

There are currently two very active threads on Supercub.org and BackCountry Flyers on this very subject. Much experience and ways around the prop issue... Ralph

Excellent thread on Supercub.org.

[pilotmike]

It's called "temporal aliasing". It's a problem related to the frame rate of the camera, the shutter speed and the speed of the prop. It's caused by the frame rate being slow relative to some repetitive motion. The prop spins (I think) around 40 revs / second. The GoPro HD runs 30 or 60 frames a second. You'd need to get quite a bit faster frame rate to eliminate this problem and even then you'd have to play it back at the fast rate and not sample it down.

I don't know much about digital video camera technology but you might be able to fool it into a slower "shutter speed" (yah... I know it doesn't actually have a shutter) by putting any sort of dark filter in front of it and fiddling with the exposure. That might blur the prop (and anything outside ) out somewhat. If it has any sort of aperature setting, making it smaller might work. Those are the "easy" solutions.

There's some post-processing software that may be able to help (adobe after effects?). If the camera is mounted (not moving around relative to the prop location) it shouldn't be too hard.

The most complete solution would be to sync the camera frame rate (exactly) with the propeller rate/position (just like the old machine guns) and keep it out of the frame. They also used to do something like that when taking video of a CRT television screen (sync with the vertical refresh). That'd make an interesting project sometime. Probably not easy.

You could also put the camera somewhere else (that doesn't show the prop).

Good luck. Let us know what you find out.

[RanRan]

The most complete solution would be to sync the camera frame rate (exactly) with the propeller rate/position (just like the old machine guns) and keep it out of the frame. They also used to do something like that when taking video of a CRT television screen (sync with the vertical refresh). That'd make an interesting project sometime. Probably not easy.

It's pretty easy with professional cameras where syncing to, say, monitor flicker because of refresh rates on the monitor, can be adjusted for. The frame rates remain the same - 23.97 or 29.97 frames per second. But a prop is not a monitor - so the best you should expect is a prop showing in two places not four or six in the frame and to the eye.

[Pete D]

This is interesting, I'm learning a lot from you experts. Myself, I would probably take the easy way out and mount the camera where it cannot see the prop.

Pete D

[RanRan]

This is interesting, I'm learning a lot from you experts. Myself, I would probably take the easy way out and mount the camera where it cannot see the prop.

Pete D

Right. There is absolutely NO way to sync a video camera shutter to a prop - since the RPMs are always changing.

A camera like the Canon 7D could be set to a high shutter speed - the prop would at least look straighter and may appear as one blade, not 3 or 4 on the screen. I shoot with the Canon 5D - they are a great series of cameras for getting crystal clear video.

[pilotmike]

I think Pete has the right idea though it is kinda cool to see cockpit view or undercarriage view which probably include some prop visibility.

Glad you jumped in here RanRan. I'm not a photography expert. I suspect you are.

I'd think that with a little hacking you could make a system that would capture the prop in the same location every time (e.g. horizontal) which I suspect would be quite a bit more pleasant to view. Even better, you could set it up to give the prop some apparent (but constant) motion. It's on my (long) project list now. I doubt there's any commercial value though .

What would be the best way to figure out the timing? How does the tach work and can you tap into the signal? Does someone have prop spin rates from idle to max for cubcrafters?

[RanRan]

I think Pete has the right idea though it is kinda cool to see cockpit view or undercarriage view which probably include some prop visibility.

Glad you jumped in here RanRan. I'm not a photography expert. I suspect you are.

Hey Mike

At 2100 RPM there will be a blade in view 70 times a second (twice a revolution).

If you're shooting at 30 frames per second with a slow shutter - say 1/30 of second - it may be possible to blur the blade to the extent that it goes invisible and yet still have smooth video.

The other way is in edit by removing offending frames. But that would be tedious work.

When Hollywood does a shot with Howard Hughes looking forward out of the cockpit - that is all green-screen - film cameras shoot at 24 frames a second - and have the same problem with syncing props.

I would suggest getting a good camera - maybe one of the Canons - and do some testing.