ASTROPHOTO mount. (Considerations)

RE: ASTROPHOTO mount. (Considerations)

lokkytron — Tue, 28 Apr 2015 17:38:38 GMT

Thank you Andy Clark, Enrico Miglino and Clem Martins for your comments and contributions.

I apologize for have been away from element14 for about a week. I've been in bed with a wild migraines.

I'm still not recovered, so I can not use too much time the computer.

But I have read the comments and my idea need to be revised... With only two axis I cannot get the rotation of sky so i need al teast one more motor. And the entire device need to be positioned manually pointing to Polaris and then make the move to point and follow an object. As i said, the whole idea need to be revised.

Thanks again for your time and contributions.

RE: ASTROPHOTO mount. (Considerations)

balearicdynamics — Fri, 24 Apr 2015 16:04:14 GMT

Hello,

take a look to these two links. This is a smaller structure but if you need we can study something that will work for the DSLR camera, that is the next step of the project.

https://www.tindie.com/products/alicemirror/tiltpan-micro-camera-kit/

and

https://www.tindie.com/products/alicemirror/tiltpan-arduino-shield/

This version is for the stop-motion photography but it doesn't matter because the applied principle is the same. In this case I have used servos and - despite that I appreciate the steppers - I saw two important things developing and testing this proejct; The first is that cheap servos has a considerable torsion and the second is that until now I was able to avoid the dual gear transmission because with microimpulses servos can move very short.

Now the product you see in the videos works with two common servos but the base can be also work fine with a 360 deg servo (not a modified one, a real full rotation servo).

With the GoPro and - more - with a heavier DSLR camera there is the problem that the direct traction (coaxial) base servo has serious difficulties to maintain a correct horizon. So, as you can see in the two attached images (done with the mobile of the piece on my desk, no-quality at all, sorry) I have designed a base with recirculating ball bearing included that fits perfectly stable. As you can see in the images of the links on Tindie above with the GoPro (about 100 gr weight) I have also used a small bronze with iron balls bearing (less than 1$ cost) to keep the camera stable when following the azimuth.

[View:/resized-image/__size/1200x899/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-fe13c90d-c7f9-4f8b-9c31-8514f787b8b5/contentimage_5F00_182682.jpg:1200:899]

[View:/resized-image/__size/1200x899/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-fe13c90d-c7f9-4f8b-9c31-8514f787b8b5/contentimage_5F00_182683.jpg:1200:899]

RE: ASTROPHOTO mount. (Considerations)

Workshopshed — Fri, 24 Apr 2015 15:01:24 GMT

The problem with steppers is you don't know where you've started from. So you can either move to a fixed point and then record steps from there or you can use some kind of feedback. I used a slotted optical disk for my clock project and homed the motors on boot.

I did some experiments with a PS/2 mouse attached to a UNO, something like that might work, perhaps with 2 mice?

[View:https://www.youtube.com/watch?v=BSddlLDFsdk:520:333]

If you move the H axis camera to the right it will balance the weight of the V axis one.

RE: ASTROPHOTO mount. (Considerations)

Robert Peter Oakes — Mon, 20 Apr 2015 02:28:13 GMT

Search for Equatorial Mounts, for years people have been making these for exactly this purpose, with a combination of crafting and some simple motors you can get what you need

The aparatus will need aligning with the north star in order to simplify the whole rig

Let me know how you get on

RE: ASTROPHOTO mount. (Considerations)

clem57 — Mon, 20 Apr 2015 00:44:42 GMT

I bet with proper gearing, you could make a precise movement with Arduino/motor...

Clem

RE: ASTROPHOTO mount. (Considerations)

lokkytron — Sun, 19 Apr 2015 22:57:21 GMT

I will answer the third by myself. Accelerometer at camera position.

It seems stupid to me now that i think in this.