First light with Equinox 120ED

[parallaxerr]

My first attempt at an observing report that is a bit of a mix with an equipment review I suppose....

I was very lucky to acquire a Sky-Watcher Equinox 120ED refractor at a bargain price this past weekend. As an added bonus there was a Televue 2” diagonal and a William Optics dovetail plate included in the sale. However, despite the good price, I was still somewhat nervous about handing over a large volume of cash for a scope whose optical performance I had not measured. So, my priority was to get it out under the stars as soon as possible and would you believe it, I had first light on the first night! I hoped this wasn’t a bad sign as we all know that new astro equipment should be accompanied by days of cloud cover!

Initial impressions of the scope are very good. There seem to be mixed opinions on the piano black finish, but I like it. The OTA is in excellent condition with no blemishes that I can find. The focuser has drawn some criticism over noisy, rough movement, but I’m happy to report that this sample is smooth in operation, perhaps the previous owner applied the light grease fix? The Crayford mechanism also feels smooth, however, I did notice the drawtube could slip with a light pull, it’s proven sufficient so far though, holding 2” diagonal and 1.25” EPs at Zenith. The dew shield is smooth when extending with a very nice level of resistance making the whole assembly feel tight, like new.

I inspected the coatings on the objective and they seemed very evenly applied and a nice deep green colour. There was a fair build-up of dust and dew marks so I gave it a blow and a wipe over with my cleaning fluid and Baader wonder cloth. The only few remaining dust particles appeared to be on the rear face of the lens cell, but I won’t let that bother me (much).

I set the Equinox up on my HEQ5/16” pillar extension/2” CG5 tripod combo that I use for imaging as the Equinox alone weighs in about the same as my imaging rig! I levelled the mount and pointed it roughly North and carried out a 3-Star alignment with a reticule eyepiece letting the mount compensate for lack of accurate alignment. Gotos were subsequently perfectly acceptable putting targets close centre, even with high power Eps.

The weather was a bit mixed. Whilst transparency appeared good, the seeing was quite poor with lots of twinkling going on and there were frequent gusts of wind. Temperature was close to 0°C so I allowed the scope to cool for 30 minutes or so.

I am by no means an experienced optical tester, however, I’ve picked up enough pointers here on SGL to know what to look for in the aberrations that bother me, namely Chromatic and Spherical aberration. Also, more recently I’ve experienced pinched optics on one of my older scopes and how it induces diffraction spikes, so I was keen to discount this.

First stop was a star test on Sirius. I immediately let out a sigh of relief as the Equinox presented near perfect diffraction rings both in intra and extra-focus. There was some intra-focus blue halo but it disappeared altogether to my eye when in focus. There was no sign of pinching as the diffraction rings appeared perfectly round and in focus, Sirius resolved to a pinpoint.

I then slewed the scope such that Sirius moved to the extremes of the field of view in several of my ES82° eyepieces and can report that there was no significant SA or astigmatism that I could note, both aberrations that I am used to seeing in my ST120.

By this time I was satisfied that the scope was a good ‘un, at least for someone of my level of experience to use visually. With street lamps starting to shut-off and my eyes becoming more dark-adapted, I moved on to some observations:

M42 – ES68° 16mm. I was immediately struck by the contrast and the structure observable in the Nebula. I can only recall seeing it this good on one occasion previously under very good conditions with an ED80, so I was surprised at what the Equinox served up under not so great skies. I observed the usual outline of the main body but to a further degree than previously, feeling like I could almost close the loop.

Trapezium in M42 – ES82° 8.8mm. Conditions simply weren’t good enough to resolve Trap E and/or F but I was convinced that they were both being hinted at. I tried the ES82° 6.7mm but the image became too soft. I’ll have to revisit this when conditions allow.

Pleaides – Vixen NPL 30mm & ES68° 16mm. The view was a little tighter than in my ST120 due to the added focal length of the Equinox, however, due to the better corrected optics I could make better use of it, framing the seven sisters right out to the edge in the 16mm whilst maintaining focus.

Double Cluster in Perseus – ES 68° 16mm. One of my favourites this and being close to Zenith it was out of the turbulent air observed lower down. Boy did the Equinox deliver on this one! Lovely, lovely, lovely, like diamonds glittering on a black velvet pillow! The colour rendition of the stars was fabulous with hints of blues and reds mixed in to the clusters. My previous best view of this had been through my C8 which got me in deep, the Equinox probably didn’t go as deep but the image was far more satisfying with regards clarity and the pinpoint stars.

By this time the moon was rising in the East, bathing me in light, so I thought it time to have a crack at what I bought the scope for, high power planetary. Well, conditions said “NO”, simple as that, the moon was well and truly on the boil! Nevertheless, I decided to have a play around anyway.

Moon – The first thing I noticed was a distinct yellow crescent around the upper edge of the moon when off-axis, but, I wasn’t too bothered. With the conditions the way they were, I put it down to atmospheric CA, which completely disappeared on axis. Concentrating on no specific feature, I was looking to see what all the contrast fuss was about. I was always sceptical when I owned my C8 that there could be any more contrast to be had on lunar targets, but the Equinox proved me wrong. The contrast between light and shadows was startling and during moments of less rubbish seeing, the sharpness of features was breathtaking.

All in all, I’m totally happy with the purchase. On a night that I knew better than to try observing, due to poor seeing, the Equinox delivered up some excellent sights. I look forward to more lunar work on nights of better seeing and hope that this positive first result transfers to viewing Jupiter and the other planets! I know some may argue there are better scopes for this and for that but I’m starting to believe the hype about a 120ED being the best all-rounder. I’m not getting my hopes up too high, I had some incredible nights viewing Jupiter in the C8 but it’s feeling like the Equinox won’t be far behind and it also has that lovely refractorness to boot!

Not a great picture, but the best I could manage with my mobile phone, it’s hard taking a photo of black things in the dark of night!

[25585]

I must get my 120 Equinox outside more! 

As you have a 2 inch diagonal, an ES92 17mm Ar (or longer fl) would give wider TFOV to compensate for your scope's greater focal length.

What kg counter weighting do you need please?

[parallaxerr]

10 minutes ago, 25585 said:

I must get my 120 Equinox outside more! 

As you have a 2 inch diagonal, an ES92 17mm Ar (or longer fl) would give wider TFOV to compensate for your scope's greater focal length.

What kg counter weighting do you need please?

If the counterweight bar was 1" longer I could get away with one 5kg counterweight. But it's not, so I have to use two, one of which is right up tight to the mount head so it's not adding much, just enough to balance. I may have to invest in a 1.8 or 3.5kg weight to go with one of the 5's.

[Pondus]

Highly enjoyable and very well written report Jon .

I read Your previous post, and it certainly sounds like a bargain buy to me.

I think the yellow cresent around the moon, off axis,  is lateral color from the eyepiece and not atmospheric Ca.

Especially if a widefield eyepiece is in use (ES82?) and the color disappears when on axis.

A very good Luck With future observations.

 

Rune

 

[Alan White]

Jon

Felt like I was observing with you, which in a way I was.....I was near Hereford for the last few nights and observed the same targets myself, but with binocular, clearly you had an advantage.

Wow what a scope you have obtained and what a great deal and what a great scope.

Sounds like it has delivered the goods.

Alan

[25585]

Incredible to believe the sky cleared that night. I was not as lucky as Jon, being in SW Somerset. 

The worry about having bought a pre-owned scope, especially for cash, is good to have dismissed!

 

[Pig]

I am so tempted to get one of these scopes, excellent report ?

[cotterless45]

Mate don't look on ENS site ! Nick.

http://ensoptical.co.uk/telescopes/skywatcher-equinox-pro-120-ed

[parallaxerr]

15 hours ago, Pondus said:

I think the yellow cresent around the moon, off axis,  is lateral color from the eyepiece and not atmospheric Ca.

Especially if a widefield eyepiece is in use (ES82?) and the color disappears when on axis.

 

Yes you're right Rune, in hindsight I'd agree it was the 82° EP causing the off-axis CA!

[parallaxerr]

16 minutes ago, cotterless45 said:

Mate don't look on ENS site ! Nick.

http://ensoptical.co.uk/telescopes/skywatcher-equinox-pro-120-ed

A nice Evostar DS-Pro too http://ensoptical.co.uk/telescopes/skywatcher-evostar-120ed-ds-pro-outfit-