I have not read any reports of aftermarket eyepieces for the Kowa Highlander. I’m specifically interested in the lowest power ones. Something to bridge the gap between the 21x Kowa and the Nikon 10x70 SP Astroluxe.
The 28mm Siebert is 50 deg apparent field, which would give about 16x and 3.1 deg true field. Not much more than the wide Kowa 21x ep’s.
Are the Sieberts well corrected? Work as advertised?
A pair of modified Panoptic 24 or Ultima 30 would be ideal, but this require custom machining.