For me the two sweetest words in the English language are low cost, as long as a product is low in price and not “cheap” it will usually grab my attention. That’s why I have such a love of the Taiwanese company Guan Sheng Optical who have been Meade telescopes main supplier for a number of years. GSO specialise in super plossls that fall into the budget category, the 15mm costs no more than £30 and is widely available.
I remember buying my first expensive eyepiece, I was so excited and reasoned that a £100 eyepiece must be considerably better than a £30, as it turned out the increase in performance was not proportional to the increase in price. At first I thought the pricier eyepiece had been a rip off but now I think it’s more that the GSO series is an absolute bona fide bargain. That’s GSO’s strength, packing so much quality in whilst keeping the cost low producing an affordable eyepiece that consistently holds it’s own against the big boys of the eyepiece world.
So what makes the GSO plossl so good? Well let’s start off with performance. The traditional 4 element design with lenses grouped in two lots of two is the most common plossl design for a reason, it offers the sharpest and crispest views on account of the low amount of potentially light scattering glass between the object being observed and the observers eye.
It works just as well in the 15mm, I’ve found this eyepiece performs excellently on solar system objects as well as the fainter galaxies and nebula that lurk in deeper space. On bright objects like the moon and planets there is minimal light scatter, far less than on any other eyepiece I’ve used in the budget category.
Banding in the Jovian atmosphere has remained sharp and pronounced, the cassini division in Saturns ring system looks so clear it feels like I could reach out and stick my finger through it. The bisecting ring of dust that makes up the rim of the sombrero that gives M104 it’s name is very defined in the 15mm as well as the furry lining of the Eskimos
hood in NGC 2392 (a dying star that has energetically thrown it’s outer layers into space leaving behind a beautiful trace work of ionized gas, a type of object known as a planetary nebula).
A greatly versatile eyepiece that performs fantastically on a wide variety of objects due to the small number of lense elements as well as the full multi coating the lenses receive that greatly improve light transmission.
Thankfully GSO haven’t forgotten about the observers comfort while enjoying the spectacular views the 15mm provides, after all what good is marvelling at a distant failing sun if you give yourself eyestrain in the process? The eye relief is around 13mm which is certainly enough and the field stop is large enough that you don’t feel like you’re peering through a pin prick.
The only thing to consider when using this eyepiece on planets or the moon which have a nasty habit of moving through the sky at a terrific pace (especially at higher magnifications) is that the field of view is only 52 degrees, to make the field larger GSO would have to add more lenses which would degrade the optical performance or force them to raise their low price, so it’s a trade off that’s worth it in my eyes.
To conclude I cannot reccomend the GSO plossl series enough specifically the 15mm which is a particularly fine example within a particularly fine grouping of eyepieces. Comfort and performance have never come at such an enticingly low price, an all round winner.
