Shooting digital video through propeller

Recently geeks.com had a special on a digital mini-hd video cam for $30. At that price I decided to pick one up to see if I could get some flying video. Next I needed a way to mount it. I found a neat little device called a "Clampette" for about $15.

Yesterday I flew the pattern a couple times to see if the cam would work out. Unfortunately as is common with CCD devices the prop shows up, in this case as a series of flickering lines.

Is anyone aware of other affordable miniature video cams where this isn't a problem?

Here's a link to the video: http://www.ericmarsh.info/Flying_Wit...e_Pattern.html It may look a little odd at times because the camera was not mounted perfectly perpendicularly.


I've attached photos of the cam and Clampette.



Attachment 1185Attachment 1186

You might be able to just throw a neutral density filter on the front of the lens to correct for the propeller effect. There is a good thread about this on supercub forums
http://www.supercub.org/forum/showth...ts-perspective

Interesting. That filter really made a big difference.

I've heard that you can also reduce the propeller artifacts by increasing the FPS or changing the exposure (if available on your camera). The ND8 affects the exposure by reducing light. I've heard a polarizer also helps.

This might be a way to get a tachometer calibration. I'm sure the frame rate is determined digitally.

I think that effect is due to the fact that cheaper cameras use a 'rolling shutter' and therefore distort high-speed objects like propellers. My old Kodak point-and-shoot and my current DSLR don't do this.

I had the same problem with my GoPro Hero. I ended up adapting the case to take a 1.4 Neutral Density filter. This did the trick nicely. I can also use a .8 filter but the effect is not quite as good. Here is a video I did using No filter, and then the l.4 ND filter. In the accompanying notes I also put links to Tim's site and it was his excellent "how-To" that I followed in solving my own problem with the GoPro. http://vimeo.com/23421934 I think that link will take you to the site. If not, just type Vimeo, John Veale into your browser and it should take you there.

Good luck.
John Veale

Quote:

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Originally Posted by Eric Marsh

Recently geeks.com had a special on a digital mini-hd video cam for $30. At that price I decided to pick one up to see if I could get some flying video. Next I needed a way to mount it. I found a neat little device called a "Clampette" for about $15.

Yesterday I flew the pattern a couple times to see if the cam would work out. Unfortunately as is common with CCD devices the prop shows up, in this case as a series of flickering lines.

Is anyone aware of other affordable miniature video cams where this isn't a problem?

Here's a link to the video: http://www.ericmarsh.info/Flying_Wit...e_Pattern.html It may look a little odd at times because the camera was not mounted perfectly perpendicularly.


I've attached photos of the cam and Clampette.



Attachment 1185Attachment 1186

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Excellent.

And thumbs high on the perfectly coordinated turns, cgaif!

Quote:

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Originally Posted by Frank Giger

Excellent.

And thumbs high on the perfectly coordinated turns, cgaif!

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And here I thought the scenery was what mattered. Guess I will have to continue to pay attention. ;) I must admit though, not all of my turns are co-ordinated that well.
Thanks for the comments....Video work is time consuming but rather fun to be able to look back at later. Good flying to you.
John

Attachment 1208Attachment 1209

A couple of pictures here showing the modification to the GoPro Hero video camera housing to accept ND filters. I used the same mounting holes as are used for the lense cover and drilled out a 'step-up' filter adapter to fit. Works great.

John (cgaif)

I bought a Canon HF R600 camcorder because I couldn't accept the prop sync I have seen on GoPro videos caused by the "rolling shutter." Problem is the all the camcorders use this shutter to get better videos so I had the same affect on my Canon. Another reason I bought the canon besides it being less than half the cost is that it has a mike input and head phone output along with an HDMI output. That way I can record the air-to-air conversations.

I resolved the prop sync issue the same way the GoPro does. I bought a screw on HD8 filter for about $35.

Can't see any of the prop unless you are facing into the sun which caused the shutter to speed up. Still it is not near as bad as seeing several prop blades through the wind screen without the filter. I am well satisfied with this camcorder and will use it to document my 1st flight from SoCal to OSH this July.

John