general purpose micro-focusser?

Robert_T · #1 04-11-2005, 02:43 PM

Hi All, having resolved (well almost) the planetary camera issue the next item on my wish list is a micro-focusser to avoid mirror-shift in fine focussing while imaging - find my ability to get critical focus is letting down my images a little. I can use either 2in or 1.25 in accessories straight into the visual back on my Mewlon, just wondered what products might be out there that I could adapt to the task (failing buying something from Takahashi, which would cause grevious bodily harm to my wallet

). Motorised would be nice, but manual cool also. Any advice gratefully received.

cheers,
Robert

[1ponders] (Paul) · #2 04-11-2005, 05:36 PM

Hi Rob, if your mewlon has the standard SCT thread at the back, probably the cheapest motorized is the non-motorised JMI , then Meade microfocuser(about $400), then the motorized JMI (about $500 and three speed). The JMI motorized can be used manually as well, but why bother

Robert_T · #3 04-11-2005, 05:42 PM

Thanks Paul, I think therein lies the problem as it doesn't match the standard SCT back. The mewlon visual back thread is much larger and can take 2 inch barrel accessories direct. Maybe something with a 2in sleeve to micro-up the focussing tube of a rack and pinion refractor would do the job? - if such exists and if the aren't too "thick". cheers, Robert

[1ponders] (Paul) · #4 04-11-2005, 06:02 PM

I doubt that meade would have anything to do that job, but maybe drop JMI a line and see what you can come up with.

I had the Meade when I had an LX200 and it was ok for visual work but found it had too much backlash (well the one I had did) for autofocusing for astrophotography. I could do it manually but there was still a bit of hit and miss. I much prefer the JMI NGF-CM, there is still backlash but not as much I've found, plus I felt it gave better fine control