Jim's Mobile NGF-DX2 Focuser
by Robert Kerwin
Jim's Mobile, Inc. has always had an outstanding reputation as a manufacturer of aftermarket telescope parts and accessories. In Spring of 1998, JMI revamped their focuser lineup. Several improvements including larger knobs and a fully enclosed frame were added to their already popular focusers.
Although I have generally been satisfied with the performance of my older NGF-3 model on my 12.5" scope, once I saw the product announcement, I knew I wanted to upgrade!
Since I was upgrading from a previous JMI focuser, installation was a simple matter of removing the old focuser and replacing it with the new.
In use, I found the focuser to be considerably smoother than NGF-3. The large, textured knobs are easier to use, especially with gloves. As expected, the focuser is a beautiful piece of machine work. The focuser comes with a 1.25/2" low-profile adapter. Four leveling screws facilitate collimation. JMI provides the two hex keys needed to make the leveling adjustments and the tension adjustment (which should not need to be done).
Are there any cons? Well, the most obvious is the price. $200 seems rather high, but compared to the price of some of the eyepieces one could put into the focuser, it's probably not too bad. One caveat: by default, the focuser comes with a 10" radius base plate. It is also available with a 5" radius and flat base plate. Be sure to specify which base plate you want, otherwise you will end up with a 10" radius base plate.