Pawl Panorama Camera

March 2008

I made a semi-experimental camera holder to take a series of pictures that can be placed edge to edge to make a wide view.

The last time I made a frame to hold a camera, it was mostly for horizontal pictures, and the camera aim was fixed in one place.
This time, I mounted the camera vertical and made a mechanism to turn the camera frame to get pictures around a full circle.
A vertical camera takes advantage of an easy aim all the way to the horizon.
And I got that idea from someone else who saw the simplicity of a vertical shaft mechanism. Chris Bentons 'Notes on KAP' site is invaluable for sharing information and ideas.

The mechanism was easy to make, the same shaft that cranks the rotation gear also trips the shutter. Turn, stop and steady, trip shutter, repeat.

Rather than go mechanical, I could have opened the camera and wired into the switch, but the warranty on this little camera would really be ka_put then.
Some people do this with remote servo control and a fast shutter camera, but that gets heavier and more complicated that it is worth for me.

Gear is from a hobby shop, for model race cars.

Mine has 32 teeth, and the pawl advances it 3 teeth at a time.
A short second pawl holds the new position while the moving pawl goes back for another bight into the gear.

11 pictures cover a full circle. And the next circle will be shifted by a third of a picture, so if I didn't like the framing of each picture on the first 10, just wait and get 10 more, and then another 10 more before the original pattern repeats.
I try to avoid the main subject being split between two pictures.

Crank drives arm with one pawl edge that drives gear.
There is adjustment so the pawl can move the gear two, three, or four teeth at one push.

The crank rod is driven by a battery power gearmotor that was meant to turn Christmas ornaments.

The entire rig with camera and 2 AAA batteries for the gearmotor weighs 17 oz (470 grams).
I don't intend to make another one. I could make it smaller, but if I ever get a bigger camera, I have room to put it into the existing frame. But a smaller frame might lessen wind resistance and swing.
There is room for further experimenting, such as placing the camera horizontal. .

HInts if you ever try one:

check how your photos look in your photo program after you rotate them so the horizon is level. I have to rotate the camera frame clockwise as seen from above so the pictures line up their edges when viewed from left to right in a photo program. I didn't check this first and made it first as a Counter clockwise, and the picture line-up was confusing.

This is a simple mechanical shutter tripper.
The crank rod advances the camera turn on one third of the cycle. and after the frame is steady, the shutter is cam tripped.
The camera needs about 7 seconds just to take the picture and store it before it's ready to take another. A full circle of pictures takes over a minute. A kite string can move a long ways out of position in a minute.

I try to stitch the picture edges at some minor line like open fields or shadows or clumps of trees so the errors don't show so bad.
And these aren't perfect panoramas like from a tripod. Rarely does a kite string hold the same position and altitude for 11 pictures in a row.

Below is my result when I stitched together a series of pictures from an early test flight.

There are actual rules or guides for stitching pictures together,
but half of those 'fly out the window' when hanging a camera on a moving kite string.
For this one, I kept the level horizon in the picture and let the distortion and overlaps fall in the shadows.

I cloned away some rough edges of the street.
And it comes out 'bent' and in reality it only has two curves. I could cut off the lower edge of the street, and no one but me would be the wiser for it.

Also, the wind varied a lot on this first test flight.
The picture on the right probably coincided with an altitude plunge of 50 feet from the previous picture 7 seconds earlier. Two streets didn't line up by 200 feet, yet only I know that and it still makes a pleasing scene.

This panoramic picture covers a half circle, 180 degrees of angle. I could stitch more on, but the subjects go into deep shadows and back-lighting so late in the day.

Hard to do this aerial panoramic method by any other way, except maybe from a stationary helicopter or an expensive crane.

In full size, this picture is 7000 pixels wide, seven times larger than shown here. Pretty good for a first attempt.
Made from seven pictures from a 4 mega pixel camera. Makes my ten-year old computer chug into low gear to process the picture when it gets large.

It's a compromise of quality and distortion for size.

Also, it is easy to survey an area for potential aerial views by using the turning rig. I just send it up, let it make three turns (33 pictures) and bring it back to check what I 'caught'.

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-------------------------------- Wrote March 8, 2008