Public Lab Research note

Dual camera KAP rig

Here is a prototype rig that performed well on its maiden flight. The design might be appropriate for matched visible/IR cameras for vertical photography, like the Canon A495s from the Balloon Mapping Kickstarter project. For such a use, it would require the addition of an intervalometer to trigger both cameras simultaneously. I am not yet sure how to add that function.

I aligned 15 photos from the test flight in MapKnitter, just because it's fun to use MapKnitter. https://mapknitter.org/tms/lone-rock-pond/openlayers.html

13 Comments

I love it, Chris!

in regards to the sway-- I see what you're seeing-- it looks like the center of gravity is off.

Two matched cameras would definitely balance better, and I bet if one camera was flipped 180, so the two were mounted tripod mount to tripod mount, the weight might be more symmetrical.

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Mathew, mounting cameras base to base is a good idea (but then the USB ports are on opposites sides). Eventually the payload will include a few AAA batteries and some USB cables. Maybe they can be placed to balance the load. But I agree that matched cameras will solve most of the problem.

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Hey all - I'm working on a dual-camera setup here (i think it may be yours, chris, since you're a backer at that level!):

http://publiclaboratory.org/wiki/t-bracket-dual-camera-rig

We've had several variations but wanted to test out a solid one for the kickstarter kits. Feedback/input welcome!

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Warren -- Most clever and elegant! Spread the cameras a bit more and you will have room to use Brooxes camera keepers (red thumb screws). Those are way handy and only $2 apiece. For example, did you try it with the existing unused hole at the opposite end of the T? It should balance without tilting. But then it would require a bigger cover if you wanted to protect the whole thing.

I am looking forward to your synchrony solution.

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Yeah i may try both ends of the T -- i was just trying to keep the lenses close together to reduce parallax.

Wow! I'd never seen those camera keepers, but they look amazing! I'll have to try them out. Maybe we can buy from Brooks in bulk for the Kickstarter:

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You might need a tee made from thinner stock to use Brooxes camera keepers. Or you can order some longer ones. Brooks' are 1" diam. knurl and 1/4" long threaded screw. This place has them with 3/8" long screw: http://mdmetric.com/shearloc/onequarter.htm For 1/4" length, you will not save much money or time compared to Brooks.

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I posted a note on auto-triggering with a circuit Mathew found, will be posting more as well:

http://publiclaboratory.org/notes/warren/2-27-2012/555-trigger-synchronized-dual-cameras

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Hi Chris - I was wondering if you'd mind putting a "main image" on this post (it's in the sidebar when you edit it) so that a nice thumbnail shows up on the videos page:

http://publiclaboratory.org/videos

I like the one with the lego men :-) but any thumbnail will do.

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Hi! I am pretty sure that the stereo-data-maker camera firmware hack allows synchronising two cameras to make photos with intervals. In fact, it is what is was made for. So no need for circuits when using canon powershots! The site: http://www.stereo.jpn.org/eng/sdm/index.htm

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Hi Jasja,

I think the stereo photography and other synchronous photography done with SDM requires that an external signal be sent to the multiple cameras. That is often done with a switch or timer (or fancy timer for bullet-time sequences). Our goal is to have the cameras receive this signal while they are aloft, so a circuit of some sort is required. SDM or CHDK can trigger a camera at any interval, but it can't synchronize two cameras without an external signal. We have figured out how to use CHDK (which has the same features as SDM) to precisely sync two cameras (http://publiclaboratory.org/notes/cfastie/4-14-2012/good-shutter-synchronization). We are now working on doing this with a $5 timer (http://publiclaboratory.org/notes/cfastie/5-2-2012/no-output-signal-ir-kit-timer). That is mostly resolved except for finding an appropriate battery. Up soon will be syncing the cameras with a $10 transmitter/receiver pair (http://publiclaboratory.org/notes/cfastie/4-22-2012/tiny-remote-control). So it's kind of like all circuits, all the time!

Chris

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It may be that the video processing in the different camera chips handle movement differently .. thus the apparent delay and re-synch Is there a steady function on one camera, which will try and smooth out movement with auto cropping of a frame larger than the recorded image? Does one of the lenses have an anti shake feature? Also if the lens barrels are moved / shook in relation to their sensors. Good work though, It sure beats building a 200 foot tripod.

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Roderick, that's a really good point that the two cameras are different models and might be processing the frames differently. Someone also commented that if the two clips are just a tiny bit out of sync they would appear to have strange behavior. So there are a lot of variables to worry about and I have decided not to. Also, I'm almost ready to post about a new dual camera rig design. One every two years seem about right?

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Thanks, I've also put together a quick video about picavet if anybody needs instructions.https://www.youtube.com/watch?v=SmRau9R2ZO8&feature=youtube_gdata_player

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