BST StarGuider 3x Deluxe Barlow

[Nightspore]

 

In my continuing quest to find a 3x Barlow that meets my particular requirements I may have struck gold. Well, black and gold at least. The ‘BST StarGuider 4-Element 3x Deluxe Apochromatic Barlow’ often retails around £70. Although I got mine twenty quid cheaper, which is slightly ironic. A few years ago I bought the 2x (3-element) version for over £80 from Astroshop. It has ‘Omegon’ written on it, but although I didn’t know it at the time, it was made or distributed by BST. These can now be purchased as a ‘BST StarGuider’ in the UK for nearly half of what I paid. I believe the 2x, 3x and 5x versions of these Barlows are sold under a variety of brand names.

 

 

The 2x version is surprisingly good and was perfect for use in a diagonal. In fact I’ve always rated it very highly. I make the 3x version an acceptable 149 grams in weight and 99mm tall.

 

 

Which is a whole 19mm taller than the 2x. However the 3x barrel is a few millimetres shorter at about 30mm. By my reckoning there is 22mm of clear aperture. It has a compression ring with a decent tightening screw and a standard M28.5 filter thread at the field lens.

 

 

The unit itself has a quadruplet optical structure as opposed to the triplet 2x BST Barlow. Unlike the 2x there is a barrel undercut. 

 

 

I was initially concerned about four elements as I would have preferred less, although producing a short 3x Barlow with three elements or less seems to be problematic to original equipment manufacturers. I’m guessing that you just can’t change the laws of physics! I assume the StarGuider is more of a conventional Barlow than a four element amplifier. The unit is aesthetically attractive, mostly painted black with a gold stripe. 

 

 

I experienced no snagging with the undercut when it was placed into an adapter with a compression ring. It held the Celestron zoom easily and securely. On the night I first tested it there were no clouds but the overall seeing wasn’t very good. With my modified ST80 I started off viewing as many double stars as I could between 50x and 150x.

 

 

As far as I could tell the 3x StarGuider revealed little or no chromatic aberration and ε Boo B was easily perceived this time. The binary companion to ε Boo A (Izar) is a hydrogen-fusing dwarf about twice the size of the Sun and separated from Izar by under three arc seconds. I had difficulty splitting these with the GSO 3x ED Barlow due to a kaleidoscopic rainbow of CA. The StarGuider had no such difficulties. 

 

 

I’ve spent two nights with the 3x StarGuider now. Predominantly observing individual stars and double stars of various magnitudes. Also some DSO’s including M57, M3 and M13. It performed admirably throughout each session. I think it’s a keeper.
 

[Marmot]

Another good review from your good self! I almost feel like mailing you some of my kit and asking you to conduct reviews on it🙂

This was of interest to me as I was very close to purchasing a BST 2x Barlow so it was interesting to read your remarks. 

Although I have a 2x Barlow already (and the performance seems ok) it lets itself down by merely having a thumbscrew to support the eyepieces. I would happily change to something of a similar quality but with a compression ring so that I felt my eyepieces were more secure.

 

keep on conducting your reviews.......I eagerly anticipate the next instalment!

[Nightspore]

13 minutes ago, Marmot said:

Another good review from your good self! I almost feel like mailing you some of my kit and asking you to conduct reviews on it🙂

This was of interest to me as I was very close to purchasing a BST 2x Barlow so it was interesting to read your remarks. 

Although I have a 2x Barlow already (and the performance seems ok) it lets itself down by merely having a thumbscrew to support the eyepieces. I would happily change to something of a similar quality but with a compression ring so that I felt my eyepieces were more secure.

 

keep on conducting your reviews.......I eagerly anticipate the next instalment!

 

Thanks. The 2x BST is actually very good. Sharp, bright and with little or no CA that I could detect. It also works well in diagonals that have helical eyepiece holder focusers, such as Baader and some William Optics. The end of the barrel doesn't usually make contact with the safety stop as it's so short. Not only that it is lightweight. I'd definitely recommend it. Try not to pay 80 quid for one though lol.

[Marmot]

Thanks for that. It’s one of a small number at the top of my list and your remarks make me feel that my thinking has been on the right lines.

i will keep scanning the marketplace.

[Nightspore]

13 hours ago, Marmot said:

Thanks for that. It’s one of a small number at the top of my list and your remarks make me feel that my thinking has been on the right lines.

i will keep scanning the marketplace.

 

These are good as well. I've owned one for years.

[Marmot]

Spooky........correct me if I am wrong, but that looks identical to one I have just purchased to try out. The only difference is that mine is marked as Revelation Astro, but they look identical.

i haven’t tried it yet, but reviews were good. If it is the same item I would definitely be interested in your experiences with yours?

Edited May 8, 2021 by Marmot

[Nightspore]

36 minutes ago, Marmot said:

Spooky........correct me if I am wrong, but that looks identical to one I have just purchased to try out. The only difference is that mine is marked as Revelation Astro, but they look identical.

i haven’t tried it yet, but reviews were good. If it is the same item I would definitely be interested in your experiences with yours?

 

Yes, the first one I bought was around six years ago from TS Optics. I mislaid it a couple of years ago and bought the Revelation like yours, probably for half the price of the TS one. Then recently the TSO turned up again. They're all GSO.

 

 

There's some controversy about how much the magnification really is. There are claims that it is more 2.2x ~ 2.3x than 2.5x. For years I suspected that it was probably not quite 2.5x. Although it's still a very good Barlow.

 

 

 

As far as I know GSO manufacture five Barlows. Three are very good, two (3x & 5x) are not so good. The 3x is the worst.

[Nightspore]

 

Guan Sheng Optical

[Nightspore]

Third outing with the ST80 and the 3x BST/Celestron zoom. I really wanted to get the 60 EDF out but conditions were pretty bad, seeing around Antoniadi 3~4 and well below average transparency. The extra 20mm of the ST80 helps in bad conditions even though it's an achromat. Eventually, at low power, I saw the Owl Cluster, Double Cluster, Coma Berenices and the Beehive. I split quite a few doubles with the 3x/zoom combo, including the Double Double. Highlights were M57 and splitting ɸ2 Cnc and ɩ Cas. I could see all three of ɩ Cas, which surprised me with the poor seeing and the fact that Cassiopeia is a bit low . 

 

 

I got ɸ2 Cnc early on in almost twilight conditions. 

 

 

I think this more or less proves the BST 3x StarGuider is the winner!

 

 

Images by courtesy of SkySafari 6 Pro

[Marmot]

A good follow up to your earlier review

 

Thanks.

[Nightspore]

12 minutes ago, Marmot said:

A good follow up to your earlier review

 

Thanks.

 

Thanks. I toyed with the idea of taking the ST102 out.

 

 

I'm planning to use it with a 2" dielectric instead of a prism, which helps with weight/balance issues.

 

 

I also want to trial the Pentax XF combined with the GSO 2.5x Barlow with the ST102. The XF can show lateral colour for lunar/planetary but I'm not sure that would be the case for doubles. 

 

 

Unless I go with the SW 7~21mm zoom, which also has similar lateral CA.

[Marmot]

I find your remarks particularly interesting as you are using the kit with fast refractors, ie ST 80 and 102, which would give results similar to mine (ST 120)

It’s interesting that you say you are hoping to try it with a dielectric instead of a prism: I assume there is a weight difference then?

It will also be interesting to see if you notice any difference, as based purely on what I have read (being new to this hobby with limited experience) dielectrics are apparently more suited to fast scopes.!

It was based on that, that when I purchased mine I immediately obtained a dielectric to use with it.

[Nightspore]

2 hours ago, Marmot said:

I find your remarks particularly interesting as you are using the kit with fast refractors, ie ST 80 and 102, which would give results similar to mine (ST 120)

It’s interesting that you say you are hoping to try it with a dielectric instead of a prism: I assume there is a weight difference then?

It will also be interesting to see if you notice any difference, as based purely on what I have read (being new to this hobby with limited experience) dielectrics are apparently more suited to fast scopes.!

It was based on that, that when I purchased mine I immediately obtained a dielectric to use with it.

 

There are a lot of theories about prisms versus mirrors. For lunar viewing I usually use a 270g 1.25" Baader-Zeiss Amici with a helical focuser and 7.5mm spacer.

 

 

For rich field I tend to prefer mirrors like the Tele Vue Enhanced Aluminium at 160g. Although I am partial to my Takahashi TKA00547 prism weighing in at 130g. As I normally use 2" eyepieces for rich field I tend to use my 2" diagonals:

 

Baader Zeiss Amici: 650g

APM Amici: 600g

Altair dielectric: 525g

Baader Amici: 455g

Baader Maxbright Dielectric: 425g

Tele Vue Everbrite 410g

Sky-Watcher dielectric: 390g

 

These can vary in weight, normally a prism will be heavier than a mirror, although it can depend on the housing and eyepiece holder. The 'posilock' type are often heavy.

 

 

Even with carbon fibre sides this Altair is heavier than a Baader Amici.

 

For planetary viewing in fast scopes I tend to prefer 1.25" BBHS prisms or BBHS mirrors.

 

 

I'm not convinced that prisms introduce false colour in faster refractors and quality prisms give better contrast and colour separation than mirrors without scatter in my experience. This seems particularly true on bright planets especially near opposition. At the end of the day the diagonal, whatever kind, needs to be compatible with the scope. This is normally discovered through trial and error.

 

Edited May 11, 2021 by Nightspore