The best investment I found that gave immediate viewing enhancement to my scopes was the addition of an electric focuser.  This gave me push button controlled motorized focusing which eliminated the need of having to touch the focuser or the OTA.  Images now "snapped" into focus without any of the associated tube shakes.

On both my SN10 and AR6 I mounted a JMI MOTOFOCUS available from:

http://www.jimsmobile.com/

After much deliberation, I chose the JMI NGF-55DM motorized Crayford zero shift focuser.  This focuser is available for the SN8 and SN10 models as a bolt on replacement - no drilling, no cutting.  It comes in a standard or deluxe model, motorized / non-motorized.  The deluxe model includes rubber gripped wheels and has a lifting capacity of eight pounds vs. six pounds for the standard.  The motorized version comes with a clutch mechanism on the left end of the shaft to permit adjustment of manual focus tension.  My ONLY criticism of this focuser is that is that I wish they would have included a second focus knob attached to the clutch end of the shaft.

The people at JMI are friendly and willing to answer your questions.  If you have any fears or doubts about which focuser fits your OTA, don’t hesitate to contact them.  Also check out their MOTOFOCUS motorized adapters which will fit the standard factory focusers on both the SN series Newtonians as well as the AR series of refractors.

When my focuser arrived via UPS, it was packed tightly in fitted foam worthy of a quality piece of precision equipment.  The parts are all finished nicely and needed very little adjustment to suit my individual feel of the action.

Mounting the new focuser was a piece of cake.  Total time was about twenty minutes with another ten minutes to align it to be perpendicular to the tube.  A task made very easy since the base includes four collimating screws to fine adjust the orientation of the focuser.

After removing the front corrector cell as described in previous sections of this guide, you simply remove the four bolts holding the stock focuser in place, and replace it with the base and gasket using the black flush mount beveled screws provided by JMI.  I placed the gasket provided by JMI between the base and the OTA and kept the factory plastic gasket for inside the OTA.  The fit is perfect with no cutting or extra holes to drill.

Once the base is mounted, add the focuser, insert your laser or crosshair sight tube and use the collimating screws in the base in conjunction with tightening the four main mounting screws to adjust the tilt of the focuser so that your crosshair or target strikes your alignment target on the opposite side of the OTA as described in the previously released Ultimate Collimation Guide.

Once you satisfied with the alignment, tighten everything down, recheck alignment one more time and then remount the corrector cell.

You can now fine tune the feel of the focuser with the small allen set screw in the back of the focuser to adjust the tension against the focus tube.  Manual focus is easily adjusted by tightening or loosening the aluminum knobs at the end of the focus shaft.

Tip:  The focuser comes with a cork washer on the large aluminum clutch wheel.  I removed the cork, polished the inside surface of both aluminum knobs very smooth with some fine jewelers rouge and then placed a thin teflon or tyvek washer sandwiched between two thin nylon washers between the two knobs.  This allowed me to maintain a much smoother and easier feel for manual focus while still maintaining no slipping in the motorized mode.

The handbox comes with two push buttons - one for each direction and a three speed selector switch.  Control is positive and precise.  Holding down the buttons for 3 seconds in either direction, kicks the motor into a high speed mode.