* Prices may differ from that shown
Skywatcher seem to have the budget Plossl market well and trully sewnup with their range of Super Plossls priced at a mere £20. One could be forgiven for overlooking these eyepieces as too cheap to be of any use but this is one instance where it's not too good to be true.
Sticking to the traditional Plossl formula, Skywatcher have used four lenses (or elements as they're known) spaced into two groups of two known as a symmetrical configuration. Using only a minimal amount of glass means less lenses to potentially degrade images. The drawback of only using four elements is a field of view
that may be considered by some to be a little restrictive.
At 7.5mm this plossl will get used for planetary and lunar work for the large majority of the time as the short focal length will provide too much magnification for effective observations of deeper space. If you don't have a driven mount to automatically move the telescope, objects will move quickly through the 52 degrees of field and this can become frustrating for some.
As well as being frustrating there are more practical implications, as the need for continuous manual readjustments of the telesope to keep the object in field make it harder to pull out faint details in the objects you're observing. It's like trying to read a book while someones talking to you, you can't give your full attention to both simultaneously.
This is the nature of the Plossl and so it becomes a toss up between affordability and field of view. To my mind, at £20, the 52 degree field is not a problem whatsoever but this will be a matter of personal choice.
Optically the Skywatcher 7.5mm is impressive for it's price, images may lose sharpness at the outer 25% of the field but there are plenty of eyepieces for treble the price that suffer worse aberrations than this.
There is a tiny bit of false colour when used in my refractor but again far less than you'd expect from a £20 eyepiece. The eye relief is a little tight but that's the nature of the beast with a low focal lengthed Plossl, some eyepiece manufacturers introduce extra elements to provide (amongst other benefits) an extended eye relief, but this would crank up the price and could potentially introduce problems, complicating the simplicity of the conventional Plossl design.
In conclusion the 7.5mm Super Plossl from Skywatcher is an astonishing value, despite the short eye relief and the image degradation in the outer quadrant you just can't get away from the fact that this is a good eyepiece in it's own right and that's before you take it's extraordinarily low price tag into account.