This is 1 of 9 eyepieces I made up this year.
I have personally made an 80mm refractor / 2 x 8" reflectors / various other sizes , collimated them using laser and traditional methods. The eyepieces are aligned to the best of my ability.
This is the biggest one. The glass came from a huge FUGICA VHS video camera, Made in Japan. It is the front zoom meniscus. The lens has not been removed from its housing.
It is an achromat, has a green coating and is flawless.....no marks at all. It is a single lens 45mm diam.......no Ramsden or Plossl so it won't work in a reflector.....all you see is the secondary. But in a refractor the view is stupendous!
I estimate the focal length to be 50-100mm (low power ) , it has a very long eye relief and a large exit pupil.
It is nagler- like .........although the focus is fuzzy at the edges. It is 90mm long and mounted by way of camera adapter rings and superglue to a copper sleeve 50mm diam. It fits in a 2" focuser snug.
If you don't like the arrangement , take it apart and marry up with another achromat to become a Plossl.
Pick up in Scoresby or post.
Enjoy.