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Upgrading a refractor

7sharp9

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7sharp9

7sharp9

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Hi, first post here :-)

I currently have a 150mm Sky-Watcher refractor and was thinking of upgrading.  

I was originally thinking of a 8 inch CST like the Celestron C8 or the Vixen L200 but thinking about it further I think I would like to stick with a refractor.  I was thinking of getting a good quality APO refractor, my budget is variable but around £1500 ish so maybe the Sky-Watcher Espirit ED 100 or maybe a 120mm model.

Reasons for upgrading?  The 150mm Sky-Watcher refractor is a bit of a beast to move about and store, and also the focussing and chromatic aberration tend to get in the way.  

Any recommendations?

Cheers

Dave.

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John

John

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Hi Dave and welcome to the forum :smiley:

I've owned a few of the 6" F8 refractors but most of my refractor observing is now done with a Skywatcher ED120 and it's a great scope. The 150's would do better on deep sky objects and could resolve slightly tighter double stars but the chromatic aberration control of the ED120 gives it the edge for planetary and lunar observing I feel. The ED120 is somewhat easier to mount and move about than the 150's were as well.

Unless you are keen to image with the scope, I'd try and go for the 120mm ED doublets like the ED120 Pro or the Equinox 120 Pro. The CA in them is really well controlled for visual observing.

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moriniboy

moriniboy

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The 120 Esprit weighs in at 10.5kg, the 120 Equinox is 6kg, for ease of handling I would go for the 120 Equinox and the CA is also very well controlled.

I love my Esprit but have to admit that sometimes in the cold its a bit of a struggle getting it on and off a high pier.

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7sharp9

7sharp9

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Unless you are keen to image with the scope, I'd try and go for the 120mm ED doublets like the ED120 Pro or the Equinox 120 Pro. The CA in them is really well controlled for visual observing.

What if imaging was going to be an option in the future? What would you plump for then?

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JG777

JG777

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I would plump for a lottery win... The game changes quite a bit if imaging is on the agenda . You would want a well corrected Apo and for the money you mention you would need to drop the aperture to 100mm and include a focal reducer / flattener in the price .

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Dave In Vermont

Dave In Vermont

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While the aperture is a consideration for imaging, the most vital link is the mount. You need a mount that is precise and smooth-running to track objects during long exposures. Video-astrophotography is somewhat more forgiving in the mounting considerations.

Clear & Steady Skies,

Dave

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John

John

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What if imaging was going to be an option in the future? What would you plump for then?

As has been said, for imaging the mount becomes more important and you may well want a triplet apochromat, both of which squeeze your budget tightly enough to require a more substantial drop in aperture.

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recceranger

recceranger

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I have had the same sort of dilemma. My thoughts are the ED120 SW's are superb and easily managed on an HEQ5 or NEQ6. I suppose the Q is the Pro or Equinox?

The Pro comes in at around just over £1000 and is good to go straight out of the box. However, if your into your AP it's worth purchasing and fitting a decent after market Crayford Focuser. The focuser on the Pro isn't bad it's just not the best for serious AP.

The problem with fitting a Crayford to the Pro is you loose the finder bracket. This was my experience when I fitted a Baader Steeltrack to my SW ED80 and it was a real song and dance fitting my finder afterwards. Additionally by the time you fork out on a good Crayford you will have payed out around £1300 or more

The Equinox comes in at around £1300 but doesn't include a diagonal or finder. Sure, it has an extendable dew shield, tube rings, looks pretty - blah blah! The optics are exactly the same as the ED120 Pro - aperture, F number the heap. It does include a much better Crayford but not as good as the Baader or a Moonlight etc.

My view personally would be go for the Pro and fit your own After Market Crayford if you big into AP. If that's the road you travel give me a bell and I will show you how you can fit the finder (unless your a Jedi at this DIY stuff!)

FYI, I'm going for the ED120 Pro mainly for visual and cracking on with ED80 for AP. However, if and when I'm using the 120 for AP then I will consider a upgrade to the issue Focuser

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cotterless45

cotterless45

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The 150 SW is a big beast. However I think I'd miss it terribly. I upgraded the focuser to a 2" dual speed Crayford. The ca has next to gone with a Baader 2" semi apo filter in the dielectric diagonal.

It does give stunning views of deep sky, planetary , lunar and those ticklish doubles. F8 means that it's not fickle with eps or narrow focusing.

I might be wrong , but if you control the ca , I don't see much point in splashing cash for an ed or apo. I like the Neil English reviews and he is a big fan of achros, especially 4". For visual use, the contrast given here is hard to beat,

Nick.

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7sharp9

7sharp9

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Im kind of put off upgrading the Sky-Watcher 150 as Im fairly picky with optics.   

Ive been looking at more APO's today Im kind of drawn to the Williams Optics FLT110 and the APM 107, both of those seems to have a really good build quality as well as good focusers as standard which sways me somewhat.

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John

John

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It's worth doing some reseach on William Optics focusers before coming to a conclusion. I've had a couple and they were OK but I have read quite a few stories on here from folks who have had issues with them, both the older models and newer ones.

I'm sure you know this but an APO of around 110mm probably won't out perform a 150mm achro. The images will have much less CA and may well seem nicer to the eye (especially if you don't like CA) and the scopes will be more managable but they won't break the laws of physics !

As a matter of interest, I used to use optical correctors called Chromacor's with my 6" F/8 achromats and, properly matched, installed and tuned, they worked wonders on the optics correcting about 90% of the CA and SA too. Alas they are no longer made and are as rare as hens teeth these days. Demand in the USA has pushed the price to many hundreds of $'s as well.

I did try a minus violet filter and it did reduce the visible CA fringing by about half but I didn't like the tint that was added to the image and of course the filter is removing light wheras the Chromacor actually puts it back where it needs to be - in the airey disk.

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7sharp9

7sharp9

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I'm sure you know this but an APO of around 110mm probably won't out perform a 150mm achro. The images will have much less CA and may well seem nicer to the eye (especially if you don't like CA) and the scopes will be more managable but they won't break the laws of physics !

I know what you mean, thats one of the things that concerned me.  That being said I use the 150mm with the reducing cap on so effectively it must be stopped down to around 110mm anyway.

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recceranger

recceranger

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I think if I was to choose between the 150 Evostar or 150 Startravel I would lean towards the latter. The Startravel just seems a more manageable OTA on an HEQ5.

The concern I would have would be the issue of collimation. I read a few articles that state the scopes can require re collimation and a few arrived out box that were somewhat off. Reports referred to the Evostar and I didn't hear anything regarding the Startravel

I know the ED120 is zero maintain which is a real draw for me

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7sharp9

7sharp9

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Quick update, in the end I decided on a Takahashi 102s with feathertouch.  Exciting!

I normally blog about software etc but Im tempted to start writing about astronomy, at least some unboxing etc :-)

Next step, mount upgrade ...

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