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BST StarGuider 3x Barlow

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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 internal blackening and baffling is competently done.




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 difficult 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.

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