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's hardly generous at 52 degrees. This is typical of the Plossl design and not a failing of Skywatcher.
At 7.5mm this plossl will get used on planets and the moon for the large majority and this is where the small field may become a problem for some. If you don't have a driven mount objects will move quickly through 52 degrees of field and this can become frustrating for some. As well as being frustrating this can detract from the image quality as you are constantly holding back a small part of your brain for manual readjustments that could be used for pulling fainter and fainter details out of an object.
This is the nature of the Plossl and so 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 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 and again is not a failing from Skywatcher.
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.