I added digital setting circles (DSC's) to the mount (photo left), converting it to a "push-to" configuration. The shaft rotation sensors are CUI AMT-102 capacitive quadrature encoders. The gear belt drive components were from eBay. No stock sprockets were available that would fit the 2" shafts so I had to bore those myself. The DSC electronics were from Dave Ek's website using a PCB kit and programmed chip from Far Circuits. These worked very well with any of the planetarium programs I tried.
Later on, I added better stepper motors and Howard Dutton's OnStep Arduino controller (photos lower right) to replace the Tech2000 DOB Driver II. OnStep converted the mount to full GOTO and worked quite well. Adding GOTO abilities to the mount deleted the need for DSC's but I left them in place in case I need them in the future.
Central Texas summers are hard on astrophotography, especially with a DSLR. Our nighttime temperatures can be in the 90's and long exposures can get very noisy. I built several versions of cooling boxes for the Canon DSLR but none were really satisfactory. So, in July of 2013 I purchased a used QHY9C one-shot color (OSC) camera. The cooling system on the QHY cameras is really good, I could achieve acceptable sensor temperatures on the hottest nights. I did a lot of imaging with the QHY and started exploring the various camera control and image processing programs. Like everything else, the OSC camera is a trade-off; you don't have to have an expensive filter wheel/filters but you trade that for long exposures and many subframes.
In August, 2014 I replaced the QHY with an SBIG ST-8300, complete with eight position filter wheel and a full set of Astrodon LRGB and BVRI filters. I added a Baader narrowband Ha, OII, and SII set to round out my selections. I was ready to settled in for some serious imaging. Read more ...
Notes on the photos to the right:
The upper photo shows the new stepper motors. They are Oriental Motors PK243M-01AA, 0.9 degrees per step (400 steps/rev). The mounting brackets were designed to directly interchange with the older Hurst motor brackets. The flexible couplers adapt the 5mm motor shafts to the 1/4" worm shafts.
The lower photo is the OnStep controller. The module mounted vertically to the back wall is a GPS receiver; the prototype board directly below it is a voltage regulator and RS-232 converter; The board in the center front is the stepper motor drivers and the blue board to the right is the Arduino Mega2560.