This picture shows the assembled electric focusser, the bracket is attached to the 10" LX200's rear cell using two 5mm stainless steel Allen (hex socket) screws. The rear cell is not quite cylindrical at this point so a few degrees offset had to be built into the bracket so the gears mesh correctly. The cell wall is only some 1/4" thick so I drilled and tapped right through (and removed the corrector plate afterwards to clean out the metal particles).

A close-up of the slip clutch, which is simply a case-hardened steel spur gear trapped between the rear of the oversize (2" dia) manual knob and a spring-loaded bronze plate. The gear is lubricated with a little molly grease to give a smooth manual focussing action. Spring tension is adjusted so that the knob can be turned manually against the friction of the clutch. In practice very little pressure is needed (my standard focusser is free-running), and the 6 springs are vastly overkill, three smaller springs would have been sufficient.

This is the control box. When powered by it's internal 9V battery focussing speed is adjustable from a top rate of 1 full turn in 30 seconds, and down to an almost imperceptable movement (which is way too slow for all practical purposes). The box has two micro switches to control direction of the focusser, and also a toggle switch to turn the unit's power off to prevent accidental activation during imaging. I was very pleased to see that the motor stops immediately the power is removed, probably due to there being lots of drag in the high ratio box, and also that a momentary 'stab' of the direction buttons gave precise incremental focussing movements.

This is another picture of the assembled focusser, I obviously had to make sure there was sufficient clearance through the forks to allow the OTA to swing through (not a problem as there is plenty of room - might be more tricky on a 12" OTA). I think my focusser is far less obtrusive than the factory Meade electric focusser which sticks out of the back of the mirror housing some considerable distance - and in my case would interfere with positioning my slide-mirror/filter-wheel assembly. You can see mine protrudes no further than the original focussing knob.

The cover for the motor assembly involved far more work than anything else! Fabricated from aluminium channel then anodised black, it offers good protection from dew & frost, and is solid enough to protect from accidental impact too. The electrical connection to the controller box is via a DIN socket. I have 2 leads I can use; either connecting to the controller box directly, or to the LX200 main panel to be controlled by the LX handset. The large focusser knob has been made with a zeroing engraved scale to facilitate resetting focus positions. Once the unfiltered focus is achieved the red mark is aligned with the mark to enable it to be reset to the same position. Further focussing operations are done just once to establish the offsets required (from the normal unfiltered image) for any additional filters which might be inserted into the lightpath (whether RGB, ND, polarising, narrowband or other special filter). These filters can then be slotted straight in and the focus offset dialed in to obtain perfect focus with each. The green & red LED indicators are for monitoring what the focusser is doing when Pictorview has control of it.

Conclusion: A successful project; the focusser is quiet and precise in action, and there is no significant vibration visible in the image even using high magnification - an end to the focussing wiggles! In practice, the fastest focussing speed (using it's own controller box) is 2 rev/min - fine for visual use, though perhaps a slower speed (1 rev/min) might be better for precision CCD focussing. The lack of overrun and virtual quantal focus shift in response to a single 'stab' of the focus control buttons make it ideal for CCD imaging. Another advantage of my focusser is that it will also connect to the LX200 main panel and can be operated through the handset as a standard Meade 2-speed focusser. If (and when) Meade ever fix the auto-focus software routine in PictorView my focusser should work with it. It appears that the Meade focusser uses 18V for high-speed focussing, and probably 9V for low-speed focussing. I didn't check for the lower voltage but the speed seems to be the same as when using the 9V battery in the controller box. Run at 18V results in a higher top speed than when using the 9V control box, a disadvantage of which is far more overrun is apparent than at 9V, though for rough focussing this is not a problem.

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