Hey Guys!
I'm planning to built a panorama-platform for my DSLR.
It has to rotate in two axes, one from 0-360 deg, and the other one from -45 to +45 deg.
Now there's one little thing I can't find: A rotary encoder, with a good resolution, lets say it should at least detect 0.1 degree.
Most devices I found had a resolution of 1 degree or more ... that's really to much.
Does anybody know which device is capable of this task?
Regards!
If you find one with that kind of resolution it will likely be very expensive. The best I could find is this one. If you use a rubber cog belt drive with the appropriate pulley ratio it can be improved.
deloarts:
Hey Guys!
I'm planning to built a panorama-platform for my DSLR.
It has to rotate in two axes, one from 0-360 deg, and the other one from -45 to +45 deg.Now there's one little thing I can't find: A rotary encoder, with a good resolution, lets say it should at least detect 0.1 degree.
Most devices I found had a resolution of 1 degree or more ... that's really to much.Does anybody know which device is capable of this task?
Regards!
Do a search on AS5601, 12bit position per revolution, now, how to get a motor to hold a 0.0879 degree accuracy is the question. I use it on a DC gearmotor with a 3" dia 96 tooth gear. I have trouble positioning it to 1.5 degree. The gear slop is +-1 degree and will get worse as wear develops.
Chuck.
Sometimes there are ways to go around what you see as your first want ("need")
Tell us a bit more about WHHAT you wan to use the output of the angle sensor FOR?...
With that kind of resolution you would likely use some form of gear reduction between the motor and the final platform. If so, use the trick that tracking telescopes use, a lower resolution encoder on the motor shaft. Celestron uses a 360:1 gearbox on their Nexstar 6/8SE scopes and a 12 step encoder mounted directly on the back of the motor.
Thank's for all the answers, I can use every information I can get!
To my project (for some of you wanted to know more of it):
I want to build, as I said, a panorama-paltform. So I want to put my camera on it, enter some parameters (focal length, amount of images, angle between shoots, etc) via 4 buttons and a display and then the system creates all necesarry pictures for a giga-pano.
Like that one: http://www.deloarts.bplaced.net/img/photography/first_pano/index.html but much larger!
For that task I really don't need such a good resolution, for one or two degrees of angle-error can be fixed by the image post-processing.
BUT: I also want to use it as a timelapse-turning-platform. And to have smooth transistions between the single pictures I need a resolution of about 0.1 degree.
The motor & gearbox aren't the problem (I use a chain and sprockets to reduce the motors speed to about 1 RPM). Btw.: The motor does already have a gearbox with 5RPM output.
LAst thing I wanted to say: I didn't think about to put a gear between the rotary encoder and the shaft. That's super simple and super easy! Thanks for that!
How big is your platform? I think you are missing the easiest angle indicator by not putting reflectors on the platform and using IR or visible light reflection to detect movement. If the platform is big enough, you should be able to detect 0.1 degree.
Paul
Good idea Paul!
It could have fit, because the platform is rather big (60mm x 60mm), but I already have a "geared" encoder in use. I just used two cogwheels with a ratio of 1/100 .. works quite well, now I have resolution of 0.01 degrees ... far more than I ever needed ^^
Interesting approach. Usually stepper motors are used for those tasks, but if it works, good job. 
I'll keep that solution in mind.
lg, couka