This unusual ‘alleged’ Abbe fully multi-coated orthoscopic has a focal length of 4.8mm. I say ‘alleged’ as I don’t actually know if this is indeed a genuine Abbe design. From what I can gather it has two lens groups consisting of a triplet and a single lens. So, the odds are it is an Abbe eyepiece and very probably manufactured on mainland China. Mine has no brand name but these eyepieces have also been sold as Kson, Ascension, Apogee and University Optics orthoscopics.
The eyepiece has no dust caps but it is supplied in its own plastic bolt case. The housing is almost exactly 50mm tall and appears to include the tapered barrel as an integral part of its aluminium housing. The barrel itself has a 28.5mm filter thread and is competently baffled. I discovered that my Baader,
The build quality seems perfectly adequate even though it’s obviously a relatively inexpensive Abbe eyepiece. Especially compared to Takahashi and Ohi built orthoscopics which can cost up to twice as much (and then some) as the forty quid (£39.60) I paid for this particular eyepiece. The
I got first light with the 4.8mm using my 72ED DS Pro. The seeing was a good Antoniadi II~I but the transparency was distinctly below average. The orthoscopic gave a convincing sharp and well contrasted view of Saturn at 87.5x. Saturn was fast approaching transit and I could see a fair bit of detail on the planetary surface and the rings, including the Cassini Division. In fact, I thought the contrast was better than the 6mm Vixen NPL that I directly compared with the 4.8mm ortho’.
I then turned to Jupiter. The detail was very well contrasted in the equatorial belts with excellent visual acuity. I occasionally witnessed some small amount of chromatic aberration around the planetary limb but it wasn’t particularly bad. I could sometimes detect an amount of scatter near the field stop and even some sporadic ghosting, although again, it wasn’t really a problem. Europa was right next to the limb and about to transit. I observed it once it was past the limb itself and could still see the moon above the surface of the gas giant for several minutes.
Meanwhile the already poor transparency was getting worse. I decided to split some doubles while I could still locate any before the steadily encroaching cloud enshrouded them. The extra 6° of field helped me find Iota Cassiopeiae more easily, but it took a 2x Barlow to properly reveal all three stars of the system at 175x. The stars were all well defined and their individual colours were easily perceived. The expected lateral astigmatism was basically undetectable when using the Barlow. But even without the Barlow it didn’t seem particularly problematic and was far closer to the field stop than I expected. I split a few more doubles at 87.5x including the Double Double, Struve 2470/74, Albireo and Almach. I could also quite distinctly see the Ring Nebula, albeit often using averted vision. Eventually I turned back towards Jupiter and could make out the
Apparently orthroscopic eyepieces are expensive because it is costly to properly and accurately cement the triplet part of the element. The use of an inexpensive housing may be a way to keep the overall unit cost down. I assume these eyepieces are made somewhere in Asia. They could be an attempt by a Chinese OEM to produce orthoscopic eyepieces in a cost effective way. If it is, they aren't quite there yet. Although one day there may be very reasonably priced, good quality, Chinese made orthoscopics on the market.