Celestron Onyx 80EDF on AZ-3 - first light :D

[cathalferris]

I decided recently that I needed to get a decent quality grab'n'go scope that I can whip out quickly and with no fuss when I get home from my 10 hour evening shifts at work. I had been missing some observation possibilities as I tend to come home tired (I have full days of college as well at the moment - doesn't help) and if the next day is a schoolday it's not a good idea to spend the night out looking up.

Scouring the small ads, I found a few likely candidates, a mark 1 Megrez-80 in the US, a few scopes in the UK but the one for me was an ad on Cloudy Nights for a scope that I hadn't heard of before. This ad was for a Celestron Onyx 80EDF, 80mm doublet semi-Apo at f6.2, 2" crayford focuser and a hard case, for a significantly cheaper price than the equivalent semi-apos that I was seeing for sale.

After a bit of research, it was clear that these Onyx scopes were brought out by Celestron as an entry into the premium small apo market, with an original price tag of ~$1100 or so. The scopes were reviewing as really good, but the price point was wrong - it was the same time that Orion brought out the 80ED at ~$800 or so for roughly the same scope. In 2008 the scope was end-of-lifed and there was a closeout sale in the US shops that had the scope for well less than $600 - and it was a steal at that price.

I made contact with the seller, and we came to an arrangement. I paid for the scope and he shipped, and it arrived 2 days ago on Monday afternoon. Tuesday morning my SW AZ-3 mount arrived (€40 deal from TS - couldn't let that pass) and while I am waiting for my solar filter and AZ3 to camera adapter I used good strength industrial temporary fasteners to attach the Onyx OTA to the mount as I don't have rings for the scope yet.

The scope constuction is high-quality. Like almost everything I own, I disassembled anything on this scope that would unscrew (excepting the objective cell - I could see that this would be asking for trouble..) a to gain an undertanding of the construction, and to put it back together tightly - shipping had loosened some mating surfaces. The internal baffling appears to be good with a low-reflection black paint applied. I will get Protostar flocking though for the tube internals just to make it that bit better as I think that this would make a difference. I'll put little bits of that flocking on certain areas of the 1.25" diagonal that I'm currently using as I can see reflections from some of the internal surfaces of the diagonal. The mounting point is a Vixen dovetail with a tripod mounting nut within it. I tried the scope on my cheap camera tripod but it was a little too shaky to be really useful. The focuser is a single-speed crayford that I adjusted the tension on to withstand the zoom eyepiece's weight towards the zenith, but the motions are smooth and non-shifting. The overall finish is a black gloss that does look quite pretty but picks up fingerprints very easily - but that doesn't bother me. The lens shade slides for transport and it's just tight enough to not slip when pointing up. I'll probably add a little more felt to the shade to stiffen it a bit. The peephole finder is useless at nighttime so I'll be organising a finder shoe to replace it and probably a half-decent RDF as a finder.

The weather was pretty awful last night, with a little intermittent high cloud and frequent heavy rain showers blowing in from the Atlantic. However the 10-20 minutes between the showers were relatively clear and I could literally grab the scope and mount and go outside and be ready and looking up in less than 30 seconds. My previous refractor experience was with a 60mm Tasco 25 years ago, and my current ETX-70 f5 achro with its colourful halos all round anything bright, so when I pointed the new scope at Jupiter I was pretty much knocked off my feet by the difference. Crisp focusing, moons like starlike points, and detail on the belts. I could spot Europa's shadow. My current high-magnification eyepiece is a 4.7mm Meade UWA so I think I need to get myself a 1.6x barlow to get the best from the fantastic optics on the scope. I'm not really in the market for a 3mm Nagler yet.

I took a look at some double stars between the clouds as well. Castor resolved into a very clean double, acres of space between the Airy disks. (I can see Airy disks - this is new ). Epsilon Lyra was pretty easy at ~105x but was wishing for 150x. Rigel was hinting at being resolved but needed more magnification to be clear. The Trapezium was clearly resolved at 3 components, and the 4th was intermittent given the clouds drifting slowly at high altitude. After a while I realised that the haziness was not helping so that was the point that I gave up.

As for colour correction, Vega had no halo in focus. The Moon was nicely framed in the fov of the 4.7, and had no discernible fringe on-axis. I could see fringing but that was dependent on my eye position relative to the exit pupil so I know it's eyepiece-related.

My eyepieces of choice to be kept in the case are going to be the Meade 4.7 UWA, the Baader mkii 8-24 zoom, and my meade 34mm SWA whenever I get around to getting a 2" diagonal.

My overall impression is that I now understand why an 80mm apo is a great complimentary scope to a 8" newt, and I can't wait for a genuinely clear night to see how it performs on deep sky in a dark sky. I'm very happy with the purchase and I'm looking forwards to using this scope more and taking those little opportunities that I was not getting to take before.

[Sarah]

Hi Cathal.

It's nice to read a first light report for the Onyx. It is a lovely scope. We got ours about 3 years ago, when it was heavily discounted, as it had been discontinued, by then. I agree that the sight hole is useless for astro viewing. We used to use a wide field eyepiece to help locate objects, but we now have the Rigel QuikFinder.

Sarah

[John]

Thats a very interesting report - thanks for posting it

You don't see much written about the Onyx's but they are clearly very nice scopes from your experiences

[damnut]

Hi Cathal,

Great report, glad to see you are upholding the tradition of taking apart before using :-)

Enjoy your new scope

Sláinte

[andrew63]

Nice report, it sounds like you have found an ideal grab and go scope. Small good quality refractors are very rewarding to view with - with the weather we have, you might end up using it more than the 8"!

andrew

[johninderby]

They are very nice scopes, but being overpriced new and only having a single speed focuser they were never big sellers so there aren't that many around.

However the focuser can easily be replaced as Baader does an adaptor for this scope.

Steeltrack RT Adapter for Celestron Onyx ED APO 80mm

http://www.365astronomy.com/steeltrack-rt-adapter-for-celestron-onyx-ed-apo-80mm-p-700.html

John

[cathalferris]

Thanks to all

The mount is quite good for what it is as well, surprisingly. I see why people have problems with the Synta glue "lubricant" A few sprays of WD40 to thin the glue and it moves with a lot less stiction than it did straight from the box. I will get around to disassembling the mount at some point over Christmas and re-greasing with a more suitable lubricant, as well as adding a wingnut to vary the altitude tension. I may add a handle to move the scope without touching the scope.

This mount will carry my new 600D every so often, as well as my 6"f5 newt if it can handle that (quite a light OTA actually). It's a fine mount for the price, for purely light visual work, and it's light enough to easily carry with one hand with the scope mounted. Exactly what I need - something I can come home after a 15 hour day to a clear sky above, grab the scope box and az3 and be looking at pretty things (in the sky!) for half an hour before lifting kit and caboodle indoors in one go, then finally getting to bed!