Who needs a gym membership? 12" Lightbridge mini-review

[GordonCopestake]

Yup I agree with Gaz, unless you need the extreme portability the truss is kinda pointless and just makes collimation more complex. I found that I left the OTA assembled pretty much 99% of the time so would have perhaps been better off with a solid tube that was cheaper. Although one thing that I did find was that the truss allowed me to more easiliy carry the OTA!

Due to finacial reasons I no longer own the 12" lightbridge though so never got around to making as many modifications as I would perhaps have liked. I can recommend the light bridge though if you plan on moving to and from a dark site often, although dont try and do it in a mini, you'll need a hatch back at least.

[Astronut]

Sorry to hear it had to go Gordon. Does this mean you have zero hardware at the moment?

OK, so the optics are identical. What about the focuser? Which 'scope has the superior focuser? Are both 'scopes kitted with a dual-speed crayford type and if not, is the Moonlite focuser from FLO fittable on either 'scope.

[GordonCopestake]

Yup zero equipment atm. I have a thread somewhere about it. I'll be buying an SCT at some point in the next month though.

I dont believe either dobs have a dual speed focuser, but the moonlite should fit either. Steve can give you more info

[FLO]

As has already been said, there isn't any advantage to buying a truss over a closed-tube design unless you need its portability.

The Meade Lightbridge series are made by the Taiwanese GSO factory and use GSO mirror sets. Skywatcher's Skyliner Dobsonians are manufactured by Synta, the Chinese company who also manufacture for Orion Optics (US) and Celestron. I doubt very much that you will see a difference in optical quality between any of them.

The Lightbridge is supplied with a 2" GSO Crayford (not dual-focus) which, whilst good, is not in the same league as a Moonlite. The Skywatcher 200P, 250PX and 300P are supplied with the standard Synta 2" R&P focuser - it isn't as bad as some say and responds well to a strip-down and re-grease but you will probably want to upgrade it at some point.

Moonlite offer direct replacemant focusers for all of them.

[Astronut]

Hi Steve

Do the Moonlite focussers have more focus travel than the standard focussers fitted to either the Lightbridge or Skywatcher?

I've been reading some reports that the single 2" eyepiece (26mm Meade 4000 series QX) supplied with the Lightbridge has to be partly pulled out from the focusser in order to achieve focus. Is this common with the Meade 4000 series eyepieces on the standard focusser fitted to the Lightbridge or have I been misinformed?

[FLO]

Do the Moonlite focussers have more focus travel than the standard focussers fitted to either the Lightbridge or Skywatcher?

If you wish, but there are other factors to consider. Most important is whether you want to image (unlikely with a Dob') or observe. It needs to be mounted low for imaging and high for observing.

The Moonlite installation kit includes a 1/2 inch curve base-plate (to suit tube diameter) plus a 1 inch spacer to give a height of 1.5 inch. The focuser itself has a thickness of 1.45" and the standard draw-tube is 2" in length. This achieves a min height of about 2.95 inches and a racked out height of approx 4.95 inches. If more in-focus is required, the 1 inch spacer can be substituted for a 1/2 inch or removed altogether. For more out-focus, an extra spacer can be inserted or a focus-extender used.

A Moonlite can be ordered with a slim spacer so that it can be mounted low for imaging and a longer draw-tube to enable enough out-focus for awkward wide-field / long focal-length eyepieces. But, this isn't a popular option as the draw-tube can intrude into the light path when racked fully in.

On my own scope (Meade SN10) I shall mount it low enough for imaging and pop in a focus-extender for observing. For a Lightbridge, I suggest you measure the maximum out-focus of the supplied focuser and order a Moonlite with an extra 10mm travel.

I've been reading some reports that the single 2" eyepiece (26mm Meade 4000 series QX) supplied with the Lightbridge has to be partly pulled out from the focusser in order to achieve focus. Is this common with the Meade 4000 series eyepieces on the standard focusser fitted to the Lightbridge or have I been misinformed?

That is true.

Some wide-field and long focal-length eyepieces require more out-focus than the standard GSO focuser can provide. The Meade 4000QX series and 2" 5000 Series are good examples. This can be overcome with a focus extender.