Antares 127mm Crayford Upgrade
The biggest shortcoming of the stock Antares refractor is the rack and pinion focuser - very stiff, an unacceptable amount of play in the drawtube, and a visual back which uses metal set screws instead of a compression ring. To remedy this weak link, I ordered a new FRM2 dual-speed Crayford focuser from ScopeStuff for $149.00; mounting it to the Antares required the FRC7 5" adapter ring, an additional $44.00. The focuser is produced by GSO, though there are no markings on either piece.
For under $200, I believe I have transformed this scope dramatically from a visual-only instrument to something I might actually be able to use for imaging. I say "believe" because, along with the focuser, the mailman also delivered clouds and likely thunderstorms for the weekend, so field tests will have to wait. But my initial impressions are positive - very smooth feel, fairly nice construction. Surely not as nice as a Moonlite or FeatherTouch, but I just couldn't bring myself to spend $500-$600 on a focuser for a $300 OTA.
I'm a little concerned about back focus, the drawtube is not nearly as long as the stock R&P focuser. Whether this will allow enough range to work without an extension tube remains to be seen. I'm fairly certain that I will need some sort of extension for imaging with the DSLR, but it might be OK for visual use. We shall see...
Installation was not too difficult: I removed the three mounting screws and gently worked the stock focuser off the OTA. There was a strip of tape around the edge of the tube which had to be removed before the new 5" mounting ring would fit. The ring was supplied with three screws, washers, and nuts; I managed to secure them without dropping anything into the tube. Finally, the focuser mounted to the ring using the three screws from the original focuser - I would have preferred new screws because the original ones are the countersunk type.
In my haste to install the FRM2, I forgot to weigh it to compare with the stock focuser. I'm going to say it is slightly heavier, but I can't be sure. There are two tension screws on the underside between the knobs: One adjusts the tension of the drawtube - by loosening it completely, the drawtube can be completely disengaged and moved in and out by hand. The second screw locks the focuser and prevents the focus knobs from moving the drawtube. This works far better than the single tension screw system I've been accustomed to.
Other notes on GSO focusers: