Beginner advice on 130P upgrades.

[cornish forest]

Hello everyone

Newbie here, After deciding to buy a telescope last year and opting for a 130p explorer and then finding out about supply issues, I managed to acquire a Skywatcher Starquest 130p from FLO. 

I've bought Turn left at Orion which has been a massive help, as has the advice on here but I have two questions: firstly upgrading the finder-scope, I've found the red dot finder obscures targets even at low settings, any ideas for a suitable replacement,think i would prefer a correct image one.  Secondly I was going to upgrade the 10mm eyepice that came with it, i thought about the BST 8mm or even the 6mm?

What do you people think given my telescope.

Thanks in advance

 

[Orange Smartie]

Hello and welcome.

No experience of them, but a lot of people use the Rigel or Telrad finders. I think the Telrad may be too big for your scope, but I'm sure someone else will be along to comment. They are essentially like red dot finders, although with rings rather than dots.

I have a set of BST starguiders that I bought to improve my viewing experience with my 150p dobsonian (I got 25mm, 12mm, 8mm and 5mm). They are great eyepieces for the money. If you wanted to save a bit of money you could get a 2x Barlow lens, which will give you twice the magnification for a given lens - so for example, an 8mm would give you 81x, assuming the focal length of your telescope is 650mm; with a Barlow that would be 162x.

[Jasonb]

Welcome to SGL!

I started with the StarQuest 130p, it's a great scope! I just upgraded to a 150P explorer, but that was more to do with a mid life crisis/retail therapy then any issues with the scope.  I got lots of great advice on here (and still do!). 

I upgraded to BSTs, I eventually went with a 25mm, 12mm and 8mm. I had looked at other ones (like the 5mm), but I decided that would be a little overkill. For example, with the 5mm and the 130P, you'd get 130x magnification. However, another good upgrade is a Barlow lens, as that effectively doubles the options for each eye piece. A 2x Barlow means the 5mm jumps up to 260x, and that probably not much good considering the average seeing conditions we get.

I went with an 8mm, which gave me 81x on its own, and I got the Baader Q-Barlow, which gives 2.25x the eye piece. That brings my 8mm up to 183x, which is decent enough but not pushing it too much.

So, I'd recommend a Barlow (the Baader Q-Barlow is well recommended on here) and some BSTs, with replacing the stock 10mm that comes with the scope your first one to replace. I got a 8mm and a 12mm as that gives me a good range of magnifications, and I replaced the stock 25mm too, just to complete the set! Between my 3 eyepieces, and the Barlow, I now have 6 magnification choices: 26x, 52x, 54x, 81x, 122x, 183x. And the Q-Barlow also has an option of removing a lens from it and it works as a 1.5x Barlow, though this only works if the eyepiece can take the lens.

Regarding the RDF, that's all I've used so far, but considering how much I enjoy star-hopping with binoculars (i.e. magnified with the right way around and right way up), I'm definitely going to upgrade to a RACI finder, so that the view in the finder matches what I'd see in binoculars etc. I just haven't done it yet.

 

 

Edited March 8, 2021 by Jasonb

[ScouseSpaceCadet]

A 9x50 Right Angle Correct Image finder compliments a pointing device. You can use both with a dual finder bracket.

Loads of people use Telrads. I've never bothered, finding a red dot and/or RACI finder just fine.

I regularly use a Multi Reticule Finder but mine was approx. £20 used so have a look on Ebay etc.

The GSO 3 Element Barlow is great. Again picked up on Ebay for £20

BST Starguiders are popular replacement eyepieces.

Plossls are easier on the wallet.

 

 

 

Edited March 8, 2021 by ScouseSpaceCadet

[Zermelo]

You would probably be better with the Rigel, as the Telrad has a large footprint. I believe the Rigel also comes with a built-in "pulse mode" that you might find useful (the same function on the Telrad requires a retrofitted module).

You're probably aware of this already, but if you get a right-angled finder, be careful you get the version you want. The 50mm model linked to by @ScouseSpaceCadet is the one that corrects both up-down and left-right (i.e. a view compatible with the naked eye or star chart), but you can also buy finders (like this one) that give an image that's erect (vertically corrected) but has left-right reversed. You shouldn't go wrong if you buy from a reputable astro supplier, but I'd be a bit cautious buying elsewhere in case they haven't described it correctly.
You'll also have to decide if you want a 9x50 or 6x30, possibly dictated by the additional weight involved vs. your mount capacity. The larger version will obviously have a better limiting magnitude, all else being equal. If you get a Rigel or Telrad to replace your red dot, you should be able to re-use the current finder shoe for a RACI. Otherwise, you'll need a dual shoe as mentioned above (unless you want to get the drill out).

[Second Time Around]

I'd very much recommend a zoom eyepiece as your workhorse.  One zoom eyepiece will cover multiple focal lengths and so is really excellent value for money.   I have both the Svbony 7-21mm at around £45 plus the Baader 8-24mm at £189.  The Baader is better, but not 4x better.

Despite having high quality fixed focal length eyepieces, I use a zoom a lot more often.  The zoom plus a Barlow lens and a low power, wide field eyepiece is often all I use the whole evening.  Your existing 25mm eyepiece will fulfil the low power role to begin with.

Fixed focal length eyepieces may be slightly better corrected when compared with a zoom at the same magnification.   But that's not always a fair comparison as that magnification may not be the optimum for a given object.  This is because one of the many advantages of a zoom is to be able to dial in precisely the best focal length.  For instance, this may be 13mm or even 13.1mm, which may actually show more detail than shorter or longer fixed focal length eyepieces.  

I particularly like the ability to increase the magnification to make use of brief moments of good seeing (a steady atmosphere).  It takes more time to swap out an eyepiece, and the opportunity may then be missed.  You can't see anything if you haven't got an eyepiece in the focusser!

Zooms also enable the field of view to be varied to frame an object to get the prettiest view.  For this reason I particularly like them for clusters.

Many of those who post here and advocate fixed focal lengths are experienced observers.  It's so easy to forget what it was like as a beginner!  A zoom eyepiece enables beginners to easily learn what difference a change of magnification makes on all the various classes of object.  It also shows them what focal lengths would be most useful to their eyes, their telescope, and their observing conditions.  They then have the option of buying/not buying the most appropriate fixed focal length eyepieces for them.  For these reasons I'd always recommend that beginners buy a zoom as their first eyepiece.

In case you're not aware a Barlow lens multiplies the magnification of any eyepiece it's used with.  It goes in the focuser before the eyepiece.  The multiplication factor varies but 2x is most common.  Some of these 2x Barlows can also be used at 1.5x, although it's not always mentioned in the blurb, and it's one of these I'd recommend.  These dual 1.5x/2x Barlows allow the black lens cell to be unscrewed from the body of the Barlow and then screwed into the filter thread at the bottom of an eyepiece to give approx 1.5x.   First Light Optics do one in their Astro Essentials range that even has a standard T thread at the top for attaching a camera.  It's just £25.  Go to https://www.firstlightoptics.com/barlows/astro-essentials-125-2x-barlow-with-t-thread.html

The exact amplification varies from eyepiece to eyepiece depending on where the field stop is located.  At 2x amplification with the 7-21mm Svbony zoom this will give you magnifications of approx 62-186x.  Most nights the seeing (atmospheric turbulence) won't be good enough to go as high as 186x and you'd get more use from the approx 46-158x that 1.5x amplification will give you.  Additionally, at a given magnification the field of view will be bigger with 1.5x amplification.  This is because the vast majority of zooms have a wider field of view at the high power end.

Good luck and do let us know how you get on.

Edited March 11, 2021 by Second Time Around

[Nyctimene]

30 minutes ago, Second Time Around said:

The zoom plus a Barlow lens and a low power, wide field eyepiece is often all I use the whole evening.

+1 for that; I'm pleased with that combo for my 130 P Flextube. I'm using for wide field the often underrated ES 26 mmf/62° LER eyepiece (giving 2.5° TFoV at 25x mag; EP: 5.2 mm). The second eyepiece is the Seben 8-24 mmf zoom; together with the excellent Baader 2.25x Turret Barlow, I can easily go up to 183x mag; TFoV 0.33°; EP 0.7 mm. Enough for all kinds of targets - moon, solar system, DSO's; lightweight, compact and affordable. Rarely, a 6 mmf UWA is useful for moon details, planetaries, double stars. No need for more or different eyepieces.

Stephan

[Clarkey]

I am largely and imager rather than visual observer. However, I would agree with the option of a zoom eyepiece for visual. I have the Baader version with a Barlow plus a 2" low power 40mm eyepiece. This just saves a lot of eyepiece changing during a session.

[Soligor Rob]

I have just bought the BST Starguider 8mm eyepiece from Flo, came recommended from SGL at sub £50 it is a good buy, the eye relief makes viewing very comfortable.

[cornish forest]

Thanks for the advice everyone, very much appreciated. I hadn't considered a zoom eyepiece before.

I will see whats in stock/can afford but think I will get either the 8mm or a zoom and persevere with my RDF for the moment.

[Neil H]

Also if your brave enough to take your telescope apart you can flock it inside this will stop stray light and give better contrast

[Spile]

I have been impressed with the Telrad (10/10) and the wide-angle low power EP is very useful (9/10). https://astro.catshill.com/finding-and-finder-scopes

The Zoom was a an expensive but worthwhile upgrade for me  - https://astro.catshill.com/the-zoom-eyepiece.  

[Zermelo]

On 10/03/2021 at 19:46, Second Time Around said:

For these reasons I'd always recommend that beginners buy a zoom as their first eyepiece.

It wasn't quite my first as a recent beginner, but I have used mine a lot since then for all the reasons mentioned, plus one more:  if you have average skies, light pollution can be a significant obstacle to spotting faint DSOs, more so if you're trying for the first time and don't know what to expect.  Longer focal length eyepieces give a wider field for searching, but also tend to increase the background sky brightness, which can more than offset the advantage for some targets. An experienced observer might well go straight to their optimum fixed length EP. For a beginner, the ability to tweak a zoom a little and find that "sweet spot" is very useful (and quite surprising, the first time you do it).

 

[keora]

After posting my question, I've a better idea of how to look for stars and what type of equipment to use. Thank you.