[dekhn]

if you really care about backlash, just measure it and then add a correction in your motor controller.

Another way to do this is to always move back to endstop zero, and only move forward. THis is very limiting.

The biggest problem I had was all my PLA prints melted in the direct sun!

[encypruon]

> if you really care about backlash

At 1200 mm equivalent a picture is only about 1.15° high, so accuracy is important :)

> just measure it and then add a correction in your motor controller.

I think your first idea doesn't really work for tilting because there is little friction and the camera isn't going to be perfectly balanced (the center of gravity also changes with the focal length and even the focus). When gravity pulls the camera towards one direction backlash is less of a problem, but when it's near the tipping point it becomes really shaky and sensitive to disturbances. Past the tipping point it is biased towards the other direction.

Preloading might be an easy fix but at the cost of acceleration.

> Another way to do this is to always move back to endstop zero, and only move forward. THis is very limiting.

At least for panning in panoramas this isn't a bad solution at all. I think both your ideas are good for panning with planned paths.

> The biggest problem I had was all my PLA prints melted in the direct sun!

Was it white PLA? So far I've only had stuff bend out of shape in the car.

[dekhn]

I've built a similar device to this (originally for a solar tracker that keeps the sun at high magnification in the middle of the frame, but it turns out to be ideal for panos as well).

It's a DSLR with crop sensor, 300mm lens, stepper+gear for azimuth and stepper+belt for altitude (with gearing to get more torque for both). I used this system with Hugin to assemble 180 degree x 180 degree, 5 degree azimuth and altitude steps (so, about 5X your resolution, I don't have the same zoom as you). Results are great- I can give this straight to hugin, update a PTO file with my known angles, and it assembles without any futher optimization. I do pan with a planned path.

If the belts are real tight, backlash is neglible (seems to be a lot smaller than any gear I could print). If you're having that much backlash on tilt (that it's shaky and sensitive) I think you might need to re-engineer the frame to be more stiff (which will cause the shakes to dissipate faster) or tune your motors (tuning velocity and acceleration). You might also be able to use a spring to keep the gear in place. I tried to get a 3D-printed worm gear working, but never made it compact enough to be practical for the altitude.

I had white PLA, in direct sunlight/90F ambient for hours, and it warped. I only noticed because I was inside watching the incoming images and the altitude staged started to "melt" causing massive positional losses.

[encypruon]

Good results without optimization at 300 mm sounds pretty impressive. Maybe belts are the way to go. Thanks for taking the time to elaborate!