Tracker testing (2)

It's almost a year to the day since I posted the last update on testing. That's not because I've not being making progress, I've just not got around to writing about it. My bad.

The "horseshoe" star shapes I was getting suggested to me that the rod gimbals needed improving. These were the supporting pieces that held the threaded rod and allow it to remain perpendicular to the axis of the tracker itself. They were crudely pivoted on the points of screws that projected through from the sides of the block that held it to the main tracker arms. It's possible that if the axis of the pivots was not truly parallel to the tracker boards and perpendicular to the tracker axis then the turning of the rod could introduce some overall oscillation to the mechanism.

Eventually I decided to replace the pivots with hinges, that would create a more precise mechanism and hopefully fix the problem. Because the supporting pieces for the rod had been made separately and just screwed on to the tracker boards, it meant I could replace them with new ones made to accommodate the new setup. The images show how this was done. The centre of the rod aligns with the axis of the hinges, thus maintaining the correct geometry. The whole thing now moves much more precisely.

It's gratifying that now I've made these improvements to the construction, the tracker tracks properly with little or no correction needed to the geometric calculations built into the software i.e. I don't need to tweak the speedfactor through the DIP switches.

Here's a 60 sec tracked exposure of the Pleiades, as captured and after adjusting the input levels with the Gimp to remove the background fogging as much as possible.

I'm pleased with this, and I'm not sure that such a simply constructed tracker could deliver any better results.

As I mentioned previously, my suburban sky is horrible with light pollution, anything much longer than a 60 sec exposure is so fogged as to be a waste of time. However, my brother lives in one of the darkest skies spots in the country, so my next plan is to invite myself for an overnight stay. Roll on the clear weather!