Replacing supplied eyepieces (BST StarGuider with fast scope?)

[Frostak]

Hello,

I'm a beginnner, just bought my first telescope about a month ago (Celestron astromaster 130/650, f/5). I'm looking to replace the supplied eyepieces (especially the 20mm erecting one). I'm on a pretty tight budget tho (ideally I want to get under 150€). I'd like to get either 3 eyepieces or 2 eyepieces and a barlow.
Currently, I'm thinking of buying the BST StarGuider (25mm, 12mm, and either 8mm or 5mm) eyepieces. In description they have written that they should be fine up till f/5, however I've read somewhere that they may have issues on faster scopes.

Does anyone have some more insight into them? Or alternatively some advice about different alternatives? As I said I'm an absolute beginner, so any advice is appritiated.
Also note that I'm from Europe, so I can't really get eyepieces from US.

Thanks in advance for any advice.

[bingevader]

Hi, people on here have used the BSTs with the SW 130 Flexitube, of similar spec, with great success, so you should be fine.

[Ruud]

Hi, welcome,

I'd go for two eyepieces and a Barlow. You'd not only get four magnifications, but every additional 1.25" eyepieces you add later on will provide two more magnifications. Of course you must plan well to avoid overlap.

A Barlow has the added advantage that it "slows down" your f/5 scope to f/10, which makes just about every eyepiece shine. (I exaggerate, a few eyepieces are bad at any focal ratio)

 

 

[Frostak]

Thanks for the answers, I knew barlows work by pretty much extending focal length of the scope but never quite realized that that actually translates to slowing the scope.
That indeed does seem like the better option. If so are there any budget barlows/eyepieces you would recommend that work well together?. I'm able to buy the BST 2x barlow with two other eyepieces (I would probably stick to 26mm, dunno about the lower focal length one), but not sure how that one performs, didn't really find any reviews about it.

[Louis D]

I did a comparative review of the BSTs (Paradigms) vs Meade HD-60s.  They're good, especially the shorter focal lengths.  The 25mm would be the one most likely to suffer at f/5 since it's already struggling at f/6.  Don't forget that our site sponsor, FLO, offers a 10% discount on 2, 15% discount on 4, and 20% discount on 7 BST Starguiders.  I have no experience with the BST Barlow.  I would watch for a used Meade 140 2x Barlow to come up for about $40.  They are a Japanese made triplet design of the 1990s that perform just as well as the Televue 2x Barlow (which I also have).

[Frostak]

Thanks for the reply, I've read the review.  I was checking them out at FLO's site.
From your review I gather that the 25mm might not be a good idea. Would you be able to suggest an alternative for lower power eyepiece (this is the eyepiece I need to replace the most) in similar price point (at around 50 eur).

[John]

2 hours ago, Frostak said:

Thanks for the reply, I've read the review.  I was checking them out at FLO's site.
From your review I gather that the 25mm might not be a good idea. Would you be able to suggest an alternative for lower power eyepiece (this is the eyepiece I need to replace the most) in similar price point (at around 50 eur).

A friend of mine who has the same scope that you do uses a Vixen NPL 30mm as his lowest power eyepiece and likes it a lot. It is currently £35.00 from First Light Optics:

https://www.firstlightoptics.com/vixen-eyepieces/vixen-npl-eyepieces.html

 

 

[Louis D]

The 32mm GSO/Revelation Plossl is also very good as a lowest power 1.25" eyepiece as well as being fairly inexpensive.  It's the second one below.

[Frostak]

@Louis D Between the GSO (apparently marketed here as TS, though I'm able to get GSO as well) and the Orion Sirius which one would you recommend? I'm able to get the Orion for about 10€ cheaper.

On the image it seems the Orion has a slightly better defined edges. Also do you happen to know if these would perform decently on f/5 scope? I'm sure it would be a step up from what I have currently but doesn't hurt to ask.
And for the highest focal lenght eyepiece is the 32mm the better choice? Before I was thinking more of getting something around 25mm considering my scope has fairly short focal length (650mm).

EDIT: I noticed now that the GSO is FMC where as Orion is only MC. Not sure how much of a difference that makes.

Edited April 15, 2020 by Frostak

[Louis D]

47 minutes ago, Frostak said:

@Louis D Between the GSO (apparently marketed here as TS, though I'm able to get GSO as well) and the Orion Sirius which one would you recommend? I'm able to get the Orion for about 10€ cheaper.

On the image it seems the Orion has a slightly better defined edges. Also do you happen to know if these would perform decently on f/5 scope? I'm sure it would be a step up from what I have currently but doesn't hurt to ask.
And for the highest focal lenght eyepiece is the 32mm the better choice? Before I was thinking more of getting something around 25mm considering my scope has fairly short focal length (650mm).

EDIT: I noticed now that the GSO is FMC where as Orion is only MC. Not sure how much of a difference that makes.

The Orion Sirius is single coated, at least the late 90s vintage I have.  It just reflects a pale purple indicative of MgF2.  The GSO are beautifully multicoated resulting in all sorts of deeply saturated color reflections more in line with premium eyepieces like Pentax XWs and Vixen SLVs.  The GSO gives nice dark backgrounds, low scatter, saturated star colors, etc.  I'd say the GSO is better corrected to the edge.  Notice in my photo how the Sirius at the top gets less distinct toward the edges while the GSO directly below it remains pretty much sharp to the edge.  Color saturation is stronger as well in the GSO.  It has a distinct and sharp field stop despite the fuzziness on the left that was most likely due to a slight misalignment of the camera lens with the eyepiece exit pupil.  The GSO is definitely worth the 10€ upcharge.  The 25mm BST and the 32mm Plossl will yield roughly the same true field of view (TFOV) on the sky owing to the former's wider apparent field of view (AFOV).  The Plossl will look sharper across the field while the BST will get fuzzy in the outer 50%.  Personally, I prefer a sharper, lower power image to a fuzzier, higher power image.

[Frostak]

Thank you for the explanation. I will get the GSO then, 10€ is not such a big deal. I also managed to get Celestron x-cel 7mm for a fairly good price, from what I've read they should be pretty decent.
So I guess I just need to figure out a 12-15mm EP and I should be good to go. Would you happen to have a recommendation in that range? I was looking at the BST 12mm which looked promising, but it's not really worth paying high shipment cost for delivery from England.

[Louis D]

1 hour ago, Frostak said:

Thank you for the explanation. I will get the GSO then, 10€ is not such a big deal. I also managed to get Celestron x-cel 7mm for a fairly good price, from what I've read they should be pretty decent.
So I guess I just need to figure out a 12-15mm EP and I should be good to go. Would you happen to have a recommendation in that range? I was looking at the BST 12mm which looked promising, but it's not really worth paying high shipment cost for delivery from England.

As long as that's an X-Cel LX and not the original X-Cel, you should be okay.  The LX is similar to the Meade HD-60 while the X-Cel have loads of spherical aberration of the exit pupil (SAEP).

Eye relief is going to get tight with a 12mm Plossl at around 8mm if the eye lens is mounted near the top, less if recessed.

What are your preferred astro vendors in Slovakia?  It would help to know what is available at a reasonable cost to you.

Below are my 12mm to 15mm eyepieces to give you some idea of the range of options available if your budget permits.

[Frostak]

Yes it is an X-Cel LX.
As far as vendors go I don't really have too much of a preference for now. I bought my scope at https://www.astroshop.eu/ and had a good experience with them. Prices also seem to be pretty reasonable in most cases.
It also shouldn't be a problem to order through https://www.amazon.de/ or https://www.ebay.de/, though delivery cost are sometimes a bit higher on these.
n Slovakia I found https://www.alemat.sk/ (I might buy the GSO from here, but they have incorrectly categorized products) and https://www.astroobchod.sk/ (which seems to be overpriced, at least some eyepieces I checked out). I didn't buy anything from them yet though. 

Thanks for the reference, I'll check them out. Some of them are definitely out of my budget though. I'd rather not go over 50-60€ per EP. I'm just starting out and I don't want to over invest for now.
Any further advice is of course greatly appreciated, if it's not too much of an inconvenience.

Edited April 15, 2020 by Frostak

[Louis D]

Having had a look at the 12mm to 15mm eyepieces at those shops, the 12mm BST Starguider (Paradigm, etc) would probably be your best bet for usability and quality at your price point.  Most of the rest are either Plossl or even simpler designs or are Konig/Erfle variants which don't do well at f/5.  Prices in general are definitely higher than in the US.  Part of it is 20% VAT is included in the advertised prices whereas US state/local sales taxes are added in later.  I noticed some don't remove the VAT when shipping to the US which is incorrect.

[Frostak]

I'll think about whether to get the BST or just wait a while and maybe get something at a higher price point.
Thanks for all the information you provided. Much appreciated!

Edited April 15, 2020 by Frostak

[John]

On 15/04/2020 at 22:37, Frostak said:

I'll think about whether to get the BST or just wait a while and maybe get something at a higher price point.
Thanks for all the information you provided. Much appreciated!

You have to spend quite a bit more to get much in the way of better optical performance than the mid focal length BST Starguiders

[PEMS]

Get the 25mm, 12mm and the 8mm. I had expected to use the 5mm more but it is rarely used in a scope.

The 25mm is to find targets, the 12mm and 8mm do the job of magnifing whatever. Don't worry or think about the worst as for some reason people need to identify the worst. And on the BST's I think I have read just about the 25mm, 18mm, 15mm and 5mm as being given as the worst. So best idea is just forget that classification.

I find they work well at f/5, like it would seem all eyepieces they produce better result in slower scopes. However as said all eyepieces seem to do that.

Better is something like the ES ranges and thay are close to 3 times the cost. Except for the ES52 range that is, but you lose field of view for the same focal length in eyepiece.

With the three above a barlow is of limited use. It would likely only be useful on the 12mm. So maybe search out a 6mm somewhere - ES52's do I think offer a 6.5mm. Actually a usefule focal length if you later decide on a 5mm BST. A 6.5mm would sit nicely between the 5mm and the 8mm.

[miguel87]

I love my BST 12mm in my f5 newt. Performs virtually as well as the Vixen SLV. Much better than my 20mm Vixen NPL

[Louis D]

I have no idea why the 5mm BST gets no love.  It views very close to my 5.2mm Pentax XL and 5-8mm SW Zoom at 5mm, just narrower and with a bit less contrast.  There's very little center to edge sharpness difference between them and the 4.5mm HD-60 as seen below in my test images taken at f/6 through an AT72ED.