Meade lightbridge : 1er test

Pris sur Cloudy nights (desole c en anglais ...)

"I’ve spent the last day or so with the LightBridge that Astronomics shipped for evaluation (direct from Meade - and BTW - a big thanks to Mike and the crew at Astronomics), and I thought some folks might be interested in some initial comments and pictures.

Right off the bat, I’ve got to hand it to Meade for bringing out the first mass produced truss telescope – and for doing it so affordably. The ability to break this telescope down for transport is indisputably nice. While I somewhat question the need for it in an 8 or 10” version, at 12” or larger, it really helps.

Assembly was straightforward. The base was the most work, and that only took about ½ an episode of Mythbusters to assemble.

When Astronomics informed me they were shipping the deluxe version, I was initially somewhat worried about the roller bearings on the base. I’d seen these before on GSO dobs, and well – to be honest have never been that enthused. There are a variety of reasons, but the biggest probably being that they simply make az motions too smooth – and the scope becomes a lazy susan. They’ve addressed that in this model. There’s a rather ingenious tensioning system involving concave washer, a roller bearing washer, and a hand knob (note the knob in the picture below). Suffice it to say that you can get any tension you want on the AZ. The Alt – well, that’s a little different matter.

The alt bearing surface is a felt-like material against aluminum, and is quite smooth. I haven’t used it at night yet, but while it’s a fair amount stiffer than premium units, it provides a nice amount of stiction. While movements are fairly stiff, they are smooth, and there does not appear to be a “break free” issue. I’ll see how it behaves when I get it under the stars.

The base has no handles, and although they could be easily added – I don’t think you really need them.
The cutouts near where the sideboards join the base serve as handles quite well.

There have been a lot of complaints about the dust cover coming off in transit and scratching the primary – the same thing happened here – however, in this case,
the damage seemed to be confined to the outer edge – there are several very small areas where the coating has been chipped off.
All told, the affected area is less than the surface area of a single retaining clip, so from a performance standpoint, it’s not a big issue.
If I was a new owner tho, I would understandably be a bit upset – especially considering that this could have been alleviated with a couple strategically placed
pieces of tape at the factory (see photo below - note that one's not the largest, but it's typical of the damage).

Otherwise – except for a single small ding/scratch or two on the outside of the unit, it arrived in good shape.

The Optical Tube Assembly goes together easily – and without tools: until you need to collimate the telescope – but I’ll get to that in a few minutes.
It’s worthwhile to take some time and make sure that everything is tight that’s supposed to be tight – secondary support, etc.
This is something I typically do every time I assemble an instrument. It only takes a moment, but often saves some pain down the road.
Nearly everything was tight – with one exception – the spider needed a slight final adjustment.

Checking collimation right out of the box – it was way off. No surprise there. Even the premium trusses typically need an adjustment after shipping.

Ironically, while they designed the assembly to be tool less, I found I needed both a Phillips head screw driver (to adjust the secondary) and a slotted screw driver
for the primary (the collimation bolts on the primary didn’t stick out far enough for me to get a good grip on them, even after trying them at various positions in their
travel).
This is something that could be easily solved – a simple replacement kit of 6 thumb bolts – three sized for the secondary, and three for the primary.
The end user could do it for themselves, but I suspect that some company (Ahemmm – Scopestuff??) will have something on the market before too long.

While the primary and secondary weren’t properly aligned, I also found that the secondary was not properly centered under the diagonal, while it’s not explained
how to center it in the manual, it’s relatively easy and only took a few minutes (it’s also not uncommon for any dob).
I’d emphasize that I’d only attempt to adjust it if you are using good quality tools to collimate and they determine it’s off.
No collimation tools ship with the telescope – I’d recommend a good laser and Cheshire (and for the really meticulous, an autocollimator).

There are a few design elements that I feel are minor issues:

1) There is no shroud, and the six pole design prevents a simple homemade solution.
If you try to wrap a shroud around a six pole design, it will clip the light path – you would need to put a stiffener in a couple of locations to take it out of the path.
Again, I suspect this will be something we will see offered separately.
In some areas of the country, a shroud does more than shield against light or the occasional dropped eyepiece – it acts as a barrier to dew and frost.
In my area – it’s pretty much a requirement.

2) As you can see in the photo below, the Alt bearings have a “lip”, and as such the base needs to be within pretty tight tolerances or they will rub against the
sidewalls – this happened with the review sample.
I didn’t notice it till I separated base and OTA to carry out to shoot these photos. It wore through the laminate on the sides in a very thing line.
This really isn’t much of an issue – even a cosmetic one because the lip covers the scratch.
However, I point it out because if you DO have this issue, you may want to clean the bearings after allowing it to wear in a bit.
This resulted in much smoother movement.

3) This may not even be an issue, but I suspect it will – so I’ll mention it.
The focuser is very close to the ends of the UTA – I suspect a glare shield would be very helpful – indeed, a friend pointed out the fact that Scopestuff already sells
one for the Lightbridge.

It was very nice to see an included fan and battery pack. A dew prevention unit for the deluxe model would be nice too, but this is something the user can easily add.

From what I can see, the finder is identical to the one sold by burgess, william optics and several other companies as their deluxe reticle finder.
It’s raised above the UTA by a plastic stalk that fits it to a standard GSO dovetail – this means that if you want to replace this with an optical finder,
it should be incredibly easy. In fact, if I were keeping this scope, I’d be tempted to do just that and add a rigel quickfinder in addition to the optical unit.

This is a very interesting telescope - the first mass produced commercial truss – offering the light gathering of a 12” telescope in a much smaller package for travel,
and while I see some initial areas for improvement (most can be done by the end user, simply and inexpensively), it has much to recommend it.
I have a feeling this is going to be a very popular telescope for Meade and that you’ll see several on various observing fields in coming summers.
I’ll keep folks updated as I get it under the stars, and you can look for a CN report coming in the future."

et en bref pour ceux qui lise pas couramment l'anglais ça dit quoi ?

Je n'ai pas eu le courage de lire plus que quelques phrases (j'ai passé ma journée à lire des articles scientifiques en anglais donc je sature!), apparament c'est du bon matériel.

MAIS:

(1) il faut se méfier des tests de Cloudynights, ils gratifient toujours les instruments et oculaires qu'ils testent (sauf si c'est vraiment de la grosse daube!);

(2) leurs conclusions prennent en compte le prix du matériel (un Newton Skywatcher est bon pour son prix mais si çà coûtait 2 à 3 fois plus cher on en serait mécontent!), du prix aux States! Or ces prix seront plus élevés en France.