BST Starguider 2x Short Barlow

[davyludo]

Maybe a bit late as I've already acquired one....but has anyone else got/used a BST Starguider 2x Short Barlow?

I struggled a bit to find any reviews on it, but fancied giving it a try.

Would be good to know what people thought or if anyone knows of any comparisons/reviews that are out there.

I'd love to be able to do a review and compare it to the standard SW one that comes free with new scopes (as that's the only other barlow I've tried)....but I certainly don't have the experience to know what I'm looking for, or the lovely descriptive, technical words to explain my findings!

Cheers, 

Davy

[Alfian]

I had looked at the Starguider barlow a while back and like yourself, Dave, couldn't find any comments at all. I think there is a point with an item that is relatively new on the market where everyone is waiting for someone else to post a review. Someone has to be the first so I'd just use it and see how you find it. If it does the job you want it to do in a way that you are happy with, without any significant loss in image quality compared to an unfettered eyepiece, then that to my mind would be a success. Give it a go and let's have your thoughts on it. It doesn't have to be a technical tour de force!

[spaceboy]

40 minutes ago, davyludo said:

 

I'd love to be able to do a review and compare it to the standard SW one that comes free with new scopes (as that's the only other barlow I've tried)....but I certainly don't have the experience to know what I'm looking for, or the lovely descriptive, technical words to explain my findings!

Cheers, 

Davy

The trick is to NOT know what you are looking for and just enjoy the views 

 

[davyludo]

Hahaha, I feared that may be the case! We're all doomed if it is down to me 

So far I've not been able to try it at night - but I had a quick shot during a cloudy day (not ideal I know). 

With my ST102....

Using my X-cel 25mm and BST barlow, I found the view of a neighbour's chimney to be very pleasant... seriously though, it seemed to "snap" into focus really well and the image seemed sharper when compared against the SW freeby. I found that the SW didn't quite have that "snap", the view was a bit softer and not quite as clear (especially towards the outer edges). I don't know whether this was maybe because it wasn't as obvious with the SW that it was in focus....maybe I was off a bit and that's why the view wasn't as sharp. I definitely noticed a difference and preferred the BST with the 25mm. I didn't feel like I had any additional glass in the path; image was clear, colours looked good and there was a lot of detail....in the moss on my neighbour's chimney.

Tried it with a 9mm as well - but I found that with the BST it looked like I was looking through heavy haze. I assume this was maybe a lot of CA seeing as it was day time? The whole view was really washed out - rather than just halos around things. The SW was similar, but certainly looked less washed out than with the BST (colours seemed a bit brighter with SW). Don't know if it was just too much glass and my short refractor was struggling to focus all those lovely photons? 

I compared 9mm and both barlows with a 5mm with no barlow - the view with the 5mm was a lot clearer and seemed to have the regular halo around objects that I associate with CA. Also tried a 3.2mm with no barlow, which was still clearer than either of the barlow views. Wasn't impressed with either barlows here - but the SW looked the be less affected. Maybe one of the clever people here can help me to understand why...and give me the right word instead of me saying "haze" all the time! Maybe something to do with the BST being 3 elements - more glass means more CA (if this "haze" was CA)? It's almost as if light was just being scattered all over the place and not being focused in the right place.

I'd appreciate any feedback or advice on things that I should look for when comparing, and words that I should be using. Obviously trying to do a comparison in daylight is a bit daft...as that's not when they're going to be used! But I wanted to have a wee play with my new toy  So I'm not going to make any assumptions on either barlow yet.

Hopefully with your help I'll learn a lot from this and this post might grow and be useful to someone in the future. I'll update with comments when I eventually get a shot at night time!

Clear skies (fat chance)!

Davy

[John]

I got one of the Skywatcher "Deluxe" 2x barlows with a used scope I bought. When I eventually tried it I was pleasantly surprised at the optical quality even when it was being used with premium eyepieces. The barlow I'm referring to is this one:

http://www.365astronomy.com/SkyWatcher-2x-De-Luxe-Achromatic-Barlow-Lens-with-T-Adapter.html?gclid=EAIaIQobChMI2uTnpefE1QIVhlcNCh1pIQa6EAYYAyABEgL_0fD_BwE

The other low cost barlows that I've owned which have proved optically good are the Revelation 2.5x and the Baader Q-Turret 2.25x. I currently have one of the Baaders that I picked up for around £25 used and it's really very good indeed for the modest cost 

I've not tried the BST Starguider 2x barlow as yet.

Edit: interesting report Davy. The trouble is high powers with an ST102 will be compromised to some extent by the limitations of an F/5 achromat objective lens so it's going to be difficult to judge if your are seeing issues from the scope rather than from the eyepiece or barlow lens.

Nighttime viewing is always more telling on optical quality than daytime viewing I find.

The bottom line is though, if you are pleased with the views then it's good

 

[davyludo]

49 minutes ago, John said:

I got one of the Skywatcher "Deluxe" 2x barlows with a used scope I bought. When I eventually tried it I was pleasantly surprised at the optical quality even when it was being used with premium eyepieces. The barlow I'm referring to is this one:

http://www.365astronomy.com/SkyWatcher-2x-De-Luxe-Achromatic-Barlow-Lens-with-T-Adapter.html?gclid=EAIaIQobChMI2uTnpefE1QIVhlcNCh1pIQa6EAYYAyABEgL_0fD_BwE

The other low cost barlows that I've owned which have proved optically good are the Revelation 2.5x and the Baader Q-Turret 2.25x. I currently have one of the Baaders that I picked up for around £25 used and it's really very good indeed for the modest cost 

I've not tried the BST Starguider 2x barlow as yet.

 

Hi John - thanks for the info 

I have read a lot of people on here talking about the Revelation 2.5x - I was interested but the numbers didn't quite work out for me. The 2x seemed to give me more of the mags I was looking for long term (thinking about future and additional scopes). I'm relying on other peoples opinions and experience a lot just now and the Revelation 2.5x seems to be a winner for the price - just unfortunate that it wasn't right for me.

Decided to be brave and just try the BST though - figuring people like the eyepieces, so hopefully their barlow would be of decent quality. I fear I may not be able to provide a suitable comparison though, as I've only tried one other barlow. I guess we'll find out! 

EDIT: yes I wondered if some of the issue was down to my ST102 and the higher mag (I know they're not really meant for higher mags) rather than the barlow. I'll try it out on my little newt as well and see if it performs any differently. I'm thinking about getting a 127mak to complement my ST102, but unfortunately that wont be until towards the end of the year  the money tree at the bottom of the garden isn't producing results at the moment!

Will keep you all posted 

[Ruud]

It's not easy to test a Barlow because you get two causes of effects which are not easy to separate. Apart from any image defects the Barlow might introduce there are the effects that come with higher magnification, like a dimmer view (the light is spread out wider), more pronounced atmospheric seeing effects and a better view of the diffraction blurring caused by the objective, or of its chromatic aberration of a refractor, none of which are caused by the Barlow. They're just the effects of using the same telescope under the same conditions at a higher magnification.

This make a comparison between one and the same eyepiece with and without Barlow quite useless. It tells you little about how the Barlow performs.

If however, you have for instance a good 20 mm eyepiece as well as a good 10 mm one, you can Barlow the 20 mm, bringing its magnification to the same level as the 10 mm and then compare the views to get some insight into how well the Barlow performs. Things to look for are the quality of star images in and out of focus, scattered light, ghost images, etc. Try high contrast targets like the Moon and the brightest stars. Daytime views can be very revealing as well, especially for chromatic aberration. Barlow don't need to be triplets to have APO performance by the way. A good doublet is good enough and will show no false colour.

One Barlow effect is purely beneficial: the light cone of the telescope is less steep after passing through the Barlow. This improves the edge of field performance of eyepieces that can't handle steep light cones well.

Used in combination with wide view, low power eyepieces a Barlow may cause vignetting. This is because after passing through a Barlow the rays diverge. A teleextender avoids this issue, but I never saw reason to buy one as none of my eyepieces vignette with my Barlows. Maybe it helps that my Barlows are long? Anyway, most people use Barlows to get high magnifications from medium magnification eyepieces. If you want to increase the magnification of low power eyepieces, a teleextender is probably a safer choice than a Barlow.

Barlows are good news. Most of them are at least decent, and the difference between a decent and an excellent Barlow is not big at all. 

Good luck with the Barlow!

[Charic]

I have the same 2x Skywatcher that John mentions, I bought that one for the 'T' adaptor facility, in order to mount my Nikon DSLR.

I mainly remove and  use just the lens cell directly attached to the eyepiece ( if/when needed )  rather than whole Barlow, this suggests somewhere around a factor of 1.6x  Barlow power ( 1.5 ~ 1.6 is often written) without the extension.

I also have Meade's Model 140! They would have you know that ..........."#140 2x Apochromatic Barlow Lens: The most advanced Barlow lens yet developed for commercial telescopes" ? ........... Its in the bag with the rest of my eyepieces, and If I have compared the two, I can't remember the result, maybe when the darker nights are back.

My Barlow actually gets more use checking collimation in conjunction with the 2nd Gen Laser, its a quick and effective last minute check.

[davyludo]

The BST one doesn't haev a T-thread actually....so no camera fun for me. 

 

I'm hopefully about to get a 127 mak - maybe that will allow me to better compare the BST and SW barlows....without effects of the short frac coming into play. Because neither barlows dealt well with ~100x in the short frac.

Thought a 12mm or 15mm would be good so that I can use the barlow to get higher mags when seeing is suitable. I guess the 12mm with a barlow would take me to the limit of the mak (and beyond our skies on most nights)....however FLO had a Vixen SLV 12mm in the clearance section so I've ordered it to try 

Exciting times with all these new toys - looking forward to the next few months where I can test them all out....if this cloud would go somewhere else! It'll give my bank balance some time to recover as well....