The Skywatcher Star Adventurer astrophotography mount is a lightweight portable battery powered astrophotography mount designed mainly for DSLR astrophotography with a 5kg payload.
The astrophotography side of the Skywatcher Star Adventurer mount is well implemented with a ST-4 port for guide camera correction and a battery life rated at 72 hours on 4 x AA batteries. The built illuminated polar scope helps with accurate polar alignment and the geared Equatorial wedge provides fine adjustment. On my mount the polar scope reticle was very accurately aligned with the RA axis and required no adjustment. One negative of the polar scope mounting design is that the trackers needs to be aligned BEFORE mounting the camera to the tracker. The additional weight of the camera and slight movement of the tripod/tracker during the camera mounting will shift the polar alignment which might be an issue for long exposures with longer focal length lenses. To counter this issue it is possible to drift align the mount but it does take time.
This was a simple astro image taken with a Canon 5D3 and Canon 100mm lens after a visual polar alignment of the Skywatcher Star Adventurer mount.
The build quality is very good with a DC motor providing the motive power controlled by a 44 slot encoder disc for closed loop feedback. Information on the guiding capabilities can be found here.
What the Skywatcher Star Adventurer is lacking, imho, is the implementation of good camera control and timelapse functionality and this post will document the development and replacement of the in-built control system so that the mount can be used for Astro and Timelapse photography.
Hopefully it will provide some information to others that want to experiment with the Star Adventurer mount.
Comet C/2014 E2 (Jacques) in Cassiopeia (23/08/14). Twenty x 40 second lights and darks stacked on the comet hence the star trails. Taken on a Canon 5D3 and Canon 100-400mm lens at 400mm FL.
Access into the mount is very simple. 4 x socket head cap screws need to be removed and the casing can be split open. Internally there is enough freedom in the wiring loom to allow the top case to be hinged back giving easy access to the main components.
The encoder mounted directly on the rear motor shaft is a 44 slot disk with 4 wires controlling the encoder generating the control pulses.
Maybe power, ground, A and B pulses? this needs to be checked. A futher check on the encoder shows it is an IR transmitter/receiver pair so only a single pulse from each slot/post pair on the encoder wheel i.e 44 pulses/revolution. At sidereal rate the motor and encoder disc spins at approx 48rpm, giving a pulse rate of (48*44)/60 = 35 pulses per second which is easily within the capability of an arduino. Also I need to look at the nominal voltage, presumably PWM driven, going to the motor. The nominal voltage going to the motor is 5 volts PWM controlled.
The output from the motor goes into a direct coupled gearbox with a 24T brass spur gear on the gearbox output. The gearbox ratio needs to be determined during the initial testing.
The 24T spur gear drives a 42T brass idler gear which, in turn, drives a 37T brass spur gear coupled directly to the brass worm. The worm drives a 144T wheel for the primary rotation.
28/01/16 update: There is a new advanced firmware available for the Adventurer which addresses some of the functional shortcomings found in the original tracker.