My Story, and I'm sticking to it!
I bought a Celestron Ultima 80 spotting scope a number of years ago when I started shooting long range BR. I haven't been too impressed with the lack of ability to see bullet holes at 300yd and beyond. I have looked through really expensive scopes with not a real dramatic improvement so I figured I get what I got!
Now, I want to use the scope for monitoring the mirage for F Class, but I would like an eyepiece with more eye relief and fixed power at around 30X or so.
Of course, I looked into Celestron for accessory eyepieces with no success. I checked out some information from this forum and heard that Baader eyepieces work on Ultima.
So, I called the Celestron Tech number. Total waste of time! First they told me there was no other eyepiece that fit Ultima due to its strange mounting. I also found out that my college physics prepared me better for understanding optics than the knowledge of the Celeston factory expert! I think Celestron is more of a marketing company than an optics design company.
So, I contacted Bader Planitarium in Germany. Not only, it turns out, is Baader the German distributor for Celestron but they also understand and design optics! They have info for adapting their eyepieces to both Zeiss and Celestron spotting scopes.
Turns out, they make a Baader Hyperian zoom eyepiece that does work on the Celestron, but it is 289 bucks!
But, for a $34 adapter, the NX4/ETX adapter # 295 8500A, and a $88 Classic Ortho eyepiece from 6mm, 10mm and 18mm. They make a 5mm and a 32 mm but the eye relief is short on the 5mm and the 32mm does not fit. I will be trying the 18mm as the overall magnification will be about 30X and the eye relief is longest of the eyepieces that fit.
To assemble, unscrew the standard eyepiece where it screws on the main body. Screw on the Baader adapter then unscrew the 1.25" adapter from the Classic Ortho and screw the eyepiece to the filter holder of the 2958500A adapter. You can then use the funny rubber eye guard or remove it.
The opinion of the guys at Baader is that Celestron and some other inexpensive brands, has pretty decent optics in the main part of the scope and it is the eyepiece that separates the men from the boys! The relatively big lenses in the body are way easier to make good than the eyepiece lenses. In addition, good zoom eyepieces need a bunch of lenses all properly coated, designed, polished and assembled to give good performance. Many "popular priced" scopes use plastic lenses in the eyepieces! As well as plastic bodies.
The "Classic Ortho" eyepiece is somewhat a copy of the traditional Ortho Baader made a few years ago. The new classic is actually an improvement.
I haven't received my parts yet so I haven't tried it but I did find a couple folks on the web that did and with good results. They all marveled at the help Baader gave. I found no one that had tried this on an Ultima 100, but one optics firm that tried the adapter as well as Baader thinks this will work on the 100 as well.
Good luck.