Advice please - choice of next scope!

[Zermelo]

I’ve been starting to think about my next scope, and knowing that order lead times are quite long at the moment, I’ve been spurred into writing by the pre-midnight appearance of Jupiter and Saturn.

I’m hoping for some wise input to break me out of analysis paralysis. Here are my thoughts so far. Please feel free to rebut/add anything at all (but you might want to note my PS). Thanks in advance.

Context: I’ve had a "budget" (but quite decent) 70mm F/10 refractor on a GEM for a while now, and recently have started to take observing more seriously, learned my way around a bit, and started to run up against aperture limits. My partner is also interested, but not so keen on spending long hours in the cold watching me failing to find stuff. We already have Telrad, barlow and a few extra EPs.

Location: most observation is likely to be from the back garden, which ClearOutside declares to be Bortle 4 (I would say slightly generous, some nearby lighting) but we have darker skies within a 15 minute drive that we would like to take advantage of with the next scope.

Likely Targets: equally interested in solar system, DSOs and doubles, so not much help on the decision there I'm afraid. Might be interested in spectroscopy at some point, but not a deal breaker. Not really keen on solar.

Imaging: we are both interested to get into this “at some point” but I have taken on board the message that visual and imaging often send you down different paths, and we have agreed that we will prioritize visual for a few seasons, and consider buying further kit later if we do decide to do imaging. It might be a bit nuanced now with decisions like mounts, but ideally we would prefer to spend only what we need for visual work now, rather than going for a higher spec that would also support photography at some unknown point in the future.

Budget: not particularly constrained, but ideally looking to spend no more than £600.

Aperture: I know some have said good things about some 130mm scopes elsewhere, but I feel anything less than 150mm doesn’t seem enough of a step up from the current scope (and also possibly because Patrick Moore always said six inches was the minimum size for a beginner! ). I even considered a 200mm but decided against on portability (and on the heights of some of the prospective observers! ).

OTA: looking to a Newt for bang/buck. There is so much choice that I’ve only been looking at Skywatcher models so far – not because I’ve already decided they’re best, but they seem to be a decent quality/price point for us and then I’ll have something to compare with if people suggest alternative ranges. So in the 150mm arena I've been looking at the Explorer 150P (F/5) and 150PL (F/8). Obviously if we were going to do imaging we’d opt for the shorter model, but for visual the F/8 is quite appealing to me with its 1200mm focal length – better contrast and magnification, more forgiving in various respects (eyepiece design, collimation, …) We’re probably not looking to spend more than £50ish per eyepiece, and may need two or three more yet, so that favours the PL. On the con side, we are obviously sacrificing some TFOV compared with the F/5, and it’s physically longer. I'm thinking a wide-field 32mm will span most DSOs with the PL. The 150P comes with a 2” Crayford focuser, the PL has a rack-and-pinion, I’ve read pros and cons for both? We’re unlikely to make use of 2” ultra-wide field EPs. Both scopes have parabolic mirrors, which I like, and I've read good things about the durability of the coatings. The PL seems to have attracted some good feedback in these pages.

Mount: Getting tricky now. But GoTo (or at least PushTo) is an absolute must, because there will be one or more observers who will be wanting fast location (and even I will probably lose the will to live if I have to star hop too much). I have seen good things written about the Skywatcher AZ GTi (and it’s a keen price), but I’m advised that it’s not too stable with anything larger than a 130mm instrument. So if I went for the F/8 150 Newt, then in the Skywatcher range we’re looking at, minimum an EQ3 pro, possibly an EQ5 pro (I’m quite comfortable with equatorials). Is it worth the extra £160 for the EQ5? Would we only see any benefit in the future for imaging, or will a 1200mm tube behave better now on an EQ5 anyway? One other factor: noise. Small back garden, so motors must be quiet, and need to be able to slip and slew by hand without the GoTo losing its fix.

So, where I am at the moment: For the sake of convenience, I’m still framing this in terms of the Skywatcher range (in the absence of some revelation of a better value offering elsewhere).

I seem to have convinced myself of the following:

- Newtonian
- 150mm
- GoTo (probably on an EQ mount )
- Skywatcher are a brand to beat

But still undecided on the focal length. I’ve found one or two “150P vs 150PL” discussions on these forums that are interesting but haven’t been conclusive for me, mainly because I have no preference on planetary vs DSO. I think more of a factor for me on the longer focal length is just the effect on stability, and the impact of that on the mount decision. We could live with the PL on an EQ3 if it were steady enough for regular visual, even knowing that we wouldn't use the mount subsequently for photography, or even for upgrading to a 200mm for visual only. Is it just a question of living with a bit longer wait for the image to settle after focusing, for example? That wouldn't be a problem. But if an EQ3 is only marginally capable handling the 150PL, that would push us into considering either the 150P on EQ3 or 150PL on EQ5.

So as I said, a bit deadlocked at the moment. If anyone can chip in with any thoughts that sway it one way or another (or unpick it and take it in some other direction), I’d be very grateful!

(PS Yes, I know I’ve not mentioned Dobs.  Yes, I have considered them, but as I mentioned, it’s important to me that we have a scope that finds and tracks objects. While I’m sure you can make a Dob do that, I don’t think that’s its raison d’être. Please don’t be offended, Dob lovers).

 

[Kyle Allen]

It’s good that you’ve thought your requirements through well. Just as a thought, Newtonians on equatorial mounts can be a bit tricky to use as the eyepiece can end up in weird positions. It’s not a big problem and easily solved by rotating the tube in its rings but can be a bit tiresome if you are constantly looking in different areas of the sky. Perhaps consider an alt-az GoTo instead if you don’t intend to do imaging?

There is a Sky-Watcher Star Discovery 150i WiFi but I don’t have any experience with it. Looking at the specs, the focuser isn’t as good as the Explorer versions. Just another option to consider though!

If you are considering the 150PL, I think the EQ3-2 would be right at its limits but it should cope fine for visual use with the short tube version. Also, you can achieve a narrow field of view with the F5 scope but you can’t achieve a wide field of view (relatively) with the F8 version.

Both of the scopes you are looking at are good quality so I’m sure you will be happy with either of them, whatever choice you make 👍

 

[Nigeyboy]

I have the 150-PL on the EQ3. I am Purely visual at the moment and can tell you the mount is indeed at the limit!! Lots of shake when you focus etc but it does settle down fairly quickly. Views are pretty good to be honest! I have spent plenty of evenings on the moon and planets and the extra focal length does make a difference. Ages ago I had the 150-P and the PLs extra length really makes a difference. 

[Zermelo]

"There is a Sky-Watcher Star Discovery 150i WiFi ..."

So there is, Kyle - I had completely missed that one on FLO.  At £389 all in, that's comparable with the EQ3 Pro combinations and quite a bit cheaper than the EQ5 Pro.  I will investigate.

[Kyle Allen]

I have no idea what it's like - the optics should be the same as the Explorer versions. I was just thinking that alt-az mounts keep the eyepiece in a comfortable viewing position and don't require polar alignment (I'm not sure how critical this has to be for GoTo to work as I've never used it). Looks like it's cheaper than the GoTo EQ3 mount too so that's a plus!

[KevinPSJ]

Hi. I have a skywatcher 150p on EQ3-2 mount and it's great for visual. I'm way way through the great book Turn Left at Orion and really enjoying the chase.

I've started dipping my toes in the imaging waters with it too and while its been an uphill struggle with polar alignment and balancing I've got some results using stacked 30s subs that have impressed family and friends enough to spur me on. 

[Cosmic Geoff]

A 6" Newtonian on a GoTo mount seems a sensible setup for you.

I would suggest having a look beyond Skywatcher mounts. Admittedly there seems little choice in between lightweight starter GoTo mounts and heavy and expensive mounts.  I recently acquired a Skywatcher EQ5 Synscan mount via an upgrade kit, and am not too impressed re. ease of use.  Selecting alignment stars is a severe pain and the final accuracy (as set up) was not impressive.  This after several 'training' sessions.  For comparison, I got some use out of my Nexstar SLT on the first night.

I would comment that you don't need an equatorial GoTo for your intended use, but whether you can find something suitable in the right weight limit and cost range is another matter. 

I would suggest erring on the generous side in mount choice. As others have pointed out, the EQ3-2 could be on the limit with a long 6" reflector.  The EQ-5 allows you more leeway.  I found the manual EQ-5 was a handy mount to have around as I could put any scope in my collection on it.  The potential odd position of eyepieces could be a nuisance, though.

It's easy to under-mount a scope or not realise what may be required.  I have a vintage brass 70mm refractor with a long focal length. I acquired it without a mount and was disconcerted to find that an adequate alt-az astro mount for it was an AZ-4 costing nearly £200.  It's an excellent scope but my modern ones are much easier to handle. I also tried it out on the manual EQ-5. A suitable GoTo mount would be an EQ-5 Synscan at around £550 (ouch!).

A left-field suggestion: look for a used Celestron C6 on the alt-az SE GoTo mount.  With luck, you should be able to find one within your budget, its alt-az Nexstar GoTo will be easy to use and, the whole outfit will be smaller and lighter than a Newtonian and EQ mount, and easier to manage.  It can be used for planetary imaging.

Edited June 10, 2020 by Cosmic Geoff
C6.

[jonathan]

£600 could be tricky as you stipulated GOTO as a requirement, and for GOTO plus a 150mm OTA minimum, I'd say that leaves you with an EQ5 Pro as a minimum mount too.  The £££ are already racking up. 

Personally I have found no problems at all for visual (I haven't done imaging with this setup but it should be possible) with a Skywatcher 150P (newtonian) on Celestron Omni CG-4 mount (which comes with the 1.75" tubular tripod legs - very steady and solid).  Alas, I don't know if the Omni CG-4 is still available separately or even as part of a bundle, it seems to have dropped off the radar, but if you can acquire one with dual axis motor drive upgrade then perhaps, just perhaps you can also plug in a GOTO handset or connect to a laptop to drive those motors (might require some modification, maybe EQ-MOD, but I don't know anything about that). 

The CG-4 mount and tripod cost me about £260 with dual axis motors if memory serves, although I only have the RA motor fitted for visual tracking purposes, it's a long time since I bought it.  Failing the CG-4, I'd say go for the EQ5 Pro or HEQ5 Pro, that mount should serve you well for many years.  The basic EQ5 has only crude gearing from what I've read, not so good and possibly not upgradable to GOTO, not even sure if they still sell it as the trend seems to be for GOTO now.  

One other thing I would say, even with GOTO you'll need to know what's good to look at - it's all very well looking through the catalogue of visbile objects on any given night from your location, but you need to keep in mind that through a 150 or 200mm scope a lot of the objects will be quite underwhelming, they might just be a tiny faint dot, or a faint grey patch, nothing much to get excited about (if you can even tell which white dot it is among the unknown background stars).  Also, GOTO systems don't always work correctly, even when you've gone through the full alignment procedure, so it may end up pointing at an empty patch of space or the wrong patch of sky and if you're not at least a bit clued up on what the object should look like or where in the sky it should be, you might end up admiring a random star for what it isn't.  Knowing the night sky is an important part of astronomy, you don't need to know a lot and it may take a while to learn the main brightest or most interesting stars, but it'll be time well spent on a lounger with a pair of binoculars and a star chart or guide book.  Swatting up on what to look for in a small guide book before you go out can be a very useful thing!  Sometimes the easiest objects are also the best.

[Zermelo]

"£600 could be tricky as you stipulated GOTO as a requirement"
yes, it could be, jonathan, but we can go a bit extra if we need to.

I'll have a hunt for the CG-4, thanks for that steer. I agree fully with your last point, and I have been putting in some hours with my existing, (very) manual scope, so I although I class myself as a newcomer, I won't be completely at the mercy of the tech 😂

[dweller25]

As already mentioned,  a 6” SCT with GOTO meets most of your requirements - apart from the price.......

https://www.firstlightoptics.com/se-series/celestron-nexstar-6se.html

Edited June 10, 2020 by dweller25

[jonathan]

1 hour ago, Zermelo said:

I'll have a hunt for the CG-4, thanks for that steer.

I think perhaps one of the most important features of the Omni CG-4 mount is the 1.75" tripod with its tubular steel legs, it looks to be the same tripd that's supplied with the HEQ5 Pro.  I would avoid anything that comes with the square aluminium legs.  The actual CG-4 mount is probably the same as the Skywatcher EQ3-2, but the EQ3-2 comes supplied with square aluminium tripod legs.  The stability of the mount starts with the ground you place it on (I find that grass is best).

[Zermelo]

The more I look at it, the more I like the Sky-Watcher Star Discovery 150i as a lower cost interim choice.
If you can look past the ABS shell and lack of collimation (or conversely, if you believe that it won't require any, then it actually becomes a bonus) then it has an awful lot going for it. And at that price, we'd still have a chunk left over for some EPs and a power tank.
Use it for two or three years, and then we'd be in a better position to decide whether we want to spend our serious money staying on the visual route (perhaps move to an 8" by then) or else into imaging. And even then, the 150i would still be a nice, compact, easy to use alternative to keep around for the right occasion.

[Cosmic Geoff]

I had forgotten the existence of the Sky-Watcher Star Discovery 150i, then I was not going to endorse it as it's another beginner scope with, it seems, cost-saving features compared with the other 150mm Newtonian models.

[ScouseSpaceCadet]

Given your budget and GOTO requirement, the 150i would be ideal if you want to use the money saved to buy accessories. The focuser is pants, but otherwise the mirrors are the same as a 150p.

The fixed primary won't need collimation, because well, it's fixed! The secondary can be adjusted if necessary. Buy a collimation cap with the telescope and check the collimation out of the box. If you think it's a dog, send it back.

I've owned a 130PS with the same ABS mirror cell. In the year I owned it, collimation was checked and never adjusted. I own a 150i tube and it arrived perfectly collimated. Skywatcher sell truck loads of scopes from 76mm up using the same construction, so don't let the ABS put you off.

 

Edited June 11, 2020 by ScouseSpaceCadet

[Zermelo]

ScouseSpaceCadet,

"The focuser is pants" - as in, not as good as on the 150P / 150PL?

collimation cap - so, no need for a cheshire, even though this is an F/5? Because we only need to check the flat?

[Skinnypuppy71]

I used the skywatcher star discovery with the 150pds for a year or so and while the mount really was at it's limit...it still slewed and tracked reasonably well for visual observing...just not on a windy night though.

[happy-kat]

There is a thread on here where a member changed the focuser to a GSO low profile one. It fits the 150mm requirement you had, the 150p version on the star discovery is kept lighter due to it's construction, there's a nature and astronomy video on it on YouTube and another member has put their videos with imaging with it and the challenges it presented with the immediate one the lack of inward focus is removed if just swap to first toe dip using camera and camera lens though using the telescope with webcam is more likely to be fine for the Moon and planets.

[Zermelo]

21 hours ago, Cosmic Geoff said:

I had forgotten the existence of the Sky-Watcher Star Discovery 150i, then I was not going to endorse it as it's another beginner scope with, it seems, cost-saving features compared with the other 150mm Newtonian models.

Yes, I admit I'm wandering all over the place, Geoff!   But I half expected my thoughts to be upended. It's all grist to the mill.

[Zermelo]

"... a member changed the focuser to a GSO low profile one"

happy-kat, do you have a link to this please, I couldn't find it.

[happy-kat]

There have been many users of the scope, probably like my heritage 130p, the focuser does what it needs to do.

Edited June 12, 2020 by happy-kat

[Shaun VS]

Just a quick note re your reference to a 32mm eyepiece. If you go down the line of the 150mm f5 reflector, please bare in mind that that this combination would give a exit pupil of approx 6.4mm. Now if you are an older observer(50+) or observing from a brighter location, then your pupil will not dilate to that size. In effect you will not get the full 150mm.

i would therefore suggest your minimum magnification should be around 30, which equates to an eyepiece in the range of around 25mm. Should you go for the longer F ratio scope then 32mm is fine, even desirable.

[Zermelo]

13 minutes ago, Shaun VS said:

Just a quick note re your reference to a 32mm eyepiece. If you go down the line of the 150mm f5 reflector, please bare in mind that that this combination would give a exit pupil of approx 6.4mm. Now if you are an older observer(50+) or observing from a brighter location, then your pupil will not dilate to that size. In effect you will not get the full 150mm.

i would therefore suggest your minimum magnification should be around 30, which equates to an eyepiece in the range of around 25mm. Should you go for the longer F ratio scope then 32mm is fine, even desirable.

Good point Shaun, I keep forgetting about exit pupil.

[ScouseSpaceCadet]

16 hours ago, Zermelo said:

ScouseSpaceCadet,

"The focuser is pants" - as in, not as good as on the 150P / 150PL?

collimation cap - so, no need for a cheshire, even though this is an F/5? Because we only need to check the flat?

The focuser doesn't compare with the 150P/150PL. It's a cheap as chips 1.25" rack and pinion. The focuser works, but it's coarse. Cleaning off the gunk that's passed off as grease and re-lubricating with lithium grease helps a little. See below:

Astro Baby's Focuser Tune Up.

The focuser is also very light weight, aiding balancing of the telescope with just a fixed small dovetail bar, while also reducing strain on the mount. This and the ABS fixtures knock around 1.5kg off the weight compared to a 150P.

I checked mine with a short cheshire and collimation cap. The collimation looked the same through both. The primary and secondary looked lined up fine, with all three primary clips perfectly placed.

[Zermelo]

OK ScouseSpaceCadet, I suppose that's no great surprise at that price, and that link is useful - I'm sure I can tackle that. I've also read that thin PTFE plumbers' tape (which I already have) can help with excessive play.
Thinking cap on again.

[Zermelo]

After another round of agonizing, I've ordered the Star Discovery 150i from FLO.
(and also a Hyperflex 7.2-21.5mm zoom, which seems to be well thought of in these parts)

Thanks again to everyone who chipped in to the discussion, and I apologize in advance for the obligatory spell of cloudy weather that will hit the south western UK in "approximately 10-15 working days time".