Orion Tri-Mag 1.25" 3x Barlow Lens

[Zeta Reticulan]

They say all things come to those who wait. I don’t know who ‘they’ are, but they may actually have a good argument. I still required a relatively lightweight, uncomplicated 3x Barlow for my ST80 grab and go kit bag. My Tele Vue 3x is a little weighty for the ST80’s aftermarket GSO focuser, especially combined with a zoom. The TV was the first 3x Barlow I ever owned and (rightly or wrongly) I tend to compare all subsequent 3x Barlows with it.

The incredibly shiny SvBony 3x Barlow looked promising and actually performed well. I wasn’t entirely confident its seemingly delicate and lightweight housing would take the leverage strain of a zoom. Furthermore its lack of internal blacking was similarly disconcerting. The GSO ED 3x initially appeared to have potential and fulfilled every criteria except the most important one. Its visual performance was woefully lacking and delivered a kaleidoscopic rainbow of false colour. The appropriately named Orion Tri-Mag 3x Barlow at £44.99 was only £6.59 more expensive than the unsatisfactory and inadequate (notwithstanding oddly psychedelic) GSO 3x ED Barlow. 

According to Orion Telescopes & Binoculars the ‘Tri-Mag’ is a multicoated two element lens with a clear aperture of 24mm. Orion also claim that it is 127mm tall. It isn’t though, and I make it 138mm, with about 53mm of that being the length of the barrel plus the element. The element contains a filter thread. The barrel itself is smooth chromed-brass without an undercut. The rest of the housing is machined aluminium. The element itself appears identical to the Orion 2x 'Shorty' Barlow.

Like the ‘Shorty’ it is internally baffled and there is no compression ring. There are two screws allocated to hold the eyepiece. Daylight trials seemed promising with clear, bright, and contrasted views. I briefly experimented with nylon screws to hold eyepieces. Eventually I returned to the original metal screws.

I got first light with the Tri-Mag on the 2nd of January. The target was the Orion Nebula and the eyepiece placed in the Orion Barlow was an Orion 7~21mm zoom. Which I considered apposite. Combined with the Tri-Mag the zoom gave a magnification range between about 57x to 171x. I could easily make out the four main Trapezium stars at about 100x. After a while I removed the Tri-Mag and used the zoom on its own. After a further period of rich field observing with 30mm and 15mm GSO SuperViews I decided to view more doubles with the zoom/Barlow combination.

First up was the Pole star. At around 150x I could only just about see the companion, Polaris B, eighteen arc seconds away from the primary star. Although this was undoubtedly due to the poor transparency. After it rained on me for a while the sky cleared somewhat. I turned to Iota Cassiopeiae. Although seeing the individual stars that constitute the triple system required some concentration.

I switched back to the 30mm SuperView for a while, fairly convinced the overall humidity, poor transparency and dodgy seeing were the main culprits for any observing difficulties. Eventually I decided to give the Orion zoom/Barlow combination a third try. Now the doubles split much more clearly with superb acuity, excellent contrast and colour separation. The clear, well defined, small blue point of Polaris B was easily perceived without a hint of any aberrations, chromatic or otherwise.

On the 5th of January I had a second session with the Tri-Mag. The seeing was a little better and Iota Cassiopeiae was much easier to split. I observed more doubles including Eta Cassiopeiae and Gamma Andromedae. When M42 was high enough for me to observe comfortably I viewed the nebula at a variety of magnifications. I experimented with different eyepieces inserted into the Barlow. A 15mm GSO SuperView gave a panoramic 80x (1mm exit pupil) and I couldn’t see any vignetting or edge distortion. A 10mm Plossl gave a sharp and contrasted view of the Trapezium stars at 120x.

In my opinion the Orion Tri-Mag 3x Barlow is definitely worth its retail price. Especially considering it is only a few quid more than the optically challenged GSO ED 3x Barlow. I’d say the Orion’s performance gives the Tele Vue 3x a run for its money.

Obviously the overall build quality of the Tri-Mag isn’t the same as the Tele Vue 3x. Having said that though the Orion Barlow is solidly built and has a chromed-brass barrel. Its two piece element seems exceptionally good and may even contain ED glass. It certainly wouldn’t surprise me if it did. I waited a long time to find a suitable 3x Barlow for my ST80. Finally it came.