For Christmas this year my wife bought me a motorised filter wheel for use in astrophotography. It has taken me this long to set it up and test that it is working, as the imaging camera I was going to use it with (ZWO ASI178MM-cooled) has not been shipped as yet.
Looking at the filter wheel, I would have to say that it looks nicely constructed. It is very thin (only 0.7″ thick, and adds only 19mm to the optical path with supplied adapters) so should be easily adapted to work with my various telescopes, together with the Orion thin off-axis guider and either my Baader Coma corrector III with the 12″ Orion Optics Newtonian, or the Astro-Physics CCDT67 telecompressor and either the Skywatcher ED80 or Astro-tech 8″ RC. And it also helps that it is not too heavy. It should work very well with the ZWO mono camera, while not tax the focusers of my telescopes too much.
It came well packed with a 10ft long mini-USB cable. It comes with 4 accessories – T2-T2male adapter, C-mount – T2 adapter, T2 – 1.25″ nosepiece, 1.25″ Dark filter attachment.
The filter set I decided to get for imaging was the Astronomik LRGB Type 2c 1.25″ filter set which blocks infrared.
To get into the filter wheel, I had to remove 7 screws. Then it was easy to mount the filters onto the numbered filter slots. The sequence I used for the filters was red, green, blue, luminance and dark filter.
After installing the filters, the cover is replaced and the filter wheel is ready for connecting to the computer. The process involved downloading the USB driver, Ascom filter wheel driver and Ascom software and everything is ready to be used.
The instructions in the manual (available online) are very clear. The filter wheel was controlled with my Surface Pro 3 and seems to change from one filter to another accurately; there is an option to allow for adjusting of the position of the filter wheel to be even better centered. It is interesting that there is an option on adjusting the focus for each filter (presumably with motorised focuser) to compensate for any focus shift of the different colour wavelengths due to the telescope optics. I might need to look into this if there is significant shift with the blue colour with my Skywatcher ED80.
But ultimately the test is when using this for imaging. I will have to wait patiently for the mono imager to arrive, and then the learning curve will have to start all over again with new image capturing software, new imaging process, learning to stack of the different colour channels to form the final image. That should all be very interesting (and hopefully not frustrating). Once I’ve had a chance to use this filter wheel out in the field, then I will post my findings here as well.
(update 23/6/16: I was asked recently what the weight of the Xagyl motorized filter wheel was. Hence I took the the picture below to answer that question.)