A few weeks back I added the Lunt LS50 to my stable of equipment. I wanted to dabble in solar imaging without getting too heavily invested monetarily, and the LS50 seemed like a good starting point, despite the fact that most threads say it isn't designed for imaging. After seeing a number of imagers getting good results with it, however, I dug a little deeper. Most were changing out the stock helical focusing unit for a crayford or Moonlite unit. Having dealt with Moonlite before, I noticed that they make a unit just for the LS50, so I immediately ordered one. Scope and focusing unit arrived within a few days of each other, and I got everything connected within minutes. Clouds slowed my progress for almost two weeks before a sunny morning allowed me to do some testing.
I originally ordered the scope with a B1200 blocking filter. I had spoken with Lunt as well as asking for information here, and everyone seemed to agree the 1200 was needed for imaging. However, when I fired up the camera in Firecapture, I quickly discovered the B1200 had way too much back focus. Even putting the camera directly atop the blocking filter, I could see I was pretty far off. I spoke with Woodland Hills Telescope and we did an exchange for the B600.
With the B600 installed, I mounted the ZWO 178MM into the clamping ring and tried to focus. The 30mm tall T2 adapter turned out to be about 2mm too tall, not quite allowing me to get a crisp image! I could see focus was very close, and since the LS50 came with two additional 30mm extensions, I went down to my shop and machined one of them down to 20mm in length. After carefully trimming the threads and test fitting with the other extension tube, I reassembled the camera and tube onto the B600. Success! I was able to focus with a little bit of reserve. The focal range of the focuser (stock or Moonlite) is quite short, and I could probably go down to 18mm and still be centered in the focal range.
Here's a shot of the S50, Moonlite focuser and ZWO 178MM:
Edited by APshooter, 14 April 2017 - 05:38 PM.