Datyson x3 Barlow

[Cosmic Geoff]

Datyson DC623 x3 "Achromatic" Barlow lens, Chinese made, cost about £12 inc postage (from ebay).

On arrival I saw it was all-metal and finished in black. All the screw parts were rattly loose so I was easily able to confirm that it contained just one negative lens element.

I wanted something to check out how my f5 200p Helios behaved at around x300, so I took a chance on ordering one of these cheap Barlows.

In my 127mm Mak it made the view bigger without adding any obvious crud of its own. In my f5 Startravel, it worked and the aberration of the scope itself masked any possible defects in the Barlow.

In the 200p, paired with a Baader Classic Ortho 10mm, it split the double Pi Aquilae (1.4") which I had struggled to see otherwise. 

Verdict: worth considering if you don't need or can't afford a premium quality Barlow. The lens alone would cost more than the asking price if ordered from an optic lens supplier. 

[Ben the Ignorant]

Does the lens look like the pic at the bottom of that page?

http://www.astrotest.it/test-reports/telextenders-and-focal-reducers/barlow-seben-3x/

Because a single lens could never respect your telescopes' quality, but a cemented doublet can.

[Cosmic Geoff]

No.

[John]

Is this the same item that you are reporting on ?:

http://tinyurl.com/hovhozo

It's slightly confusing that the vendor refers to it as an achromatic and also an apochromatic barlow lens in the advertisment

More confusing still if it actually has only a singlet lens in it as you appear to have found.

Still, if it enabled you to split Pi Aquilae with your 8" F/5 newt at 333x then it must be doing something right