I had an opportunity to borrow a 12″ LX850 OTA so I snatched it. I’ve previously owned three 12″ F/10 Schmidt-Cassegrains and reviewed a 12″ RCX back in the day – and my current primary instrument is a 12″ F/8 RC so I have a pretty good idea what to expect. I haven’t done any serious analysis yet but I’ve had it on the mount for a few sessions and can make some comments.
All my leftover accessories from the old F/10 scopes fit the new model. I was going to re-use my tube rings but after taking a look at the beefy radius blocks on the new OTA I decided to stick with the supplied dovetail plate. It’s very strong and I trust it to remain rigid more than I trusted the original Losmandy plates on my old tubes (hence the tube rings). Plus the new plate has adjustments to eliminate cone error! I haven’t bothered with that but if I owned one of these and planned to use it long term I would. The metal dewshield dropped right on, though of course it’s the old shiny finish. Speaking of finish – that pebbly new finish grows on one after a while. I didn’t think I’d like it. I even found the old 3.25″ Meade flange for my Moonlight focuser so I was able transfer that to the new Meade tube.
About the focuser: This is as good as I hoped it would be when I first heard about the new design. Firm, smooth, no backlash and little or no image shift. I haven’t noticed any but will watch it with a camera when time permits so I can make a definitive statement. I wouldn’t have bothered with the Moonlight but I rely on being able to focus remotely. I believe that with one of the old belt-drive Robofocus motors this focuser could be controlled just as accurately as my stepper-equipped Moonlight. I checked image scale with the Moonlight in place, by the way, and was a little surprised at the modest focal length increase. It’s running at 2530mm (F/8.3); I’m used to seeing a larger increase from adding a focuser to an SCT. Makes sense after some thought, though. The F/8 tube uses a secondary with a smaller multiplier. The good news is that this probably also means less focus shift with temperature, but of course that isn’t eliminated (thus my need for remote focus capability).
This OTA is probably about as close to what the RCX could have been as anything we are likely to see. It has the same great optics set and solves the traditional focuser issues, though in a different way. The RCX did have some other nice features. I won’t miss the internal dew heater much; that’s easy enough to do otherwise. The remote collimation was very cool, but my gear isn’t moved around so I don’t need to collimate frequently. I did really, really like the through-the-tube airflow with rear fans and front vents; that is a great way to end tube currents. I think that when this one goes back home I’ll miss it as much as I missed the RCX.