Ostara FF 27mm v Celestron X-Cel 25mm v Ostara ED 21mm eyepiece shootout

Have just done my own little wide field eyepiece shoot-out. This was following a request from a customer looking for a good wide angle E/P for his Olivon T800 spotting scope that he purchased from us.
I tested on an Olivon T650. Eyepieces tested were the Ostara FF 27mm, Ostara ED 21mm and a Celestron X-CeL LX 25mm.
As these were different focal lengths, I did not compare on the field of view.
What I did go by was overall sharpness, contrast and edge of field quality. This may surprise some, but the winner by a mile was the Ostara FF 27mm. It showed much better edge of field sharpness over the other two + less chromatic aberration across the field (despite not being marketed as ED)
Just proves that sometimes you need to forget what it says on the tin, and simply look through them. The same applies to spotters, binoculars and telescopes.