So, to all celestron ultima users. i wanted to do this for a while, but baaden planetarium eyepieces were just too damn expensive, made no sense to spend a $300 on an eyepiece for a $200 scope.
so i tried a chinesium one - SVBONY 1.25inch Telescope Eyepieces 68° 9mm Ultra Wide Angle Fully Multi-Coated
FMC 68-Degree Ultra Wide long eye Relief Eyepiece Standard 1.25" Inch Astronomy Telescope 4 Piece Eyepiece Kit Super Wide 68 Degree apparent field offers expansive views of the moon, star clusters, and the Milky Way Multi-element design delivers sharp images with good color correction and...
www.ebay.com
it is not an exact fit, but not too difficult neither. the bottom part of the lower lens housing needs to be cut off by lower line (after you unscrew the lens out of it, of course).
the upper highlighted extrusion needs to be grinded down, so it all would fit into the celestron. that lens element then needs to be threaded down enough along that cut pipe holder so it would focus same way as the original eyepiece, to get to infinity focus properly. where it was in stock tube was too high.
the result is very nice optically, way better than the stock, in my opinion. opinions differ, of course.
View attachment 678647
here is the end result - could have been done prettier, of course, but i was not too concerned about esthetics of it.
i just tested it - the police department door is about 300-500 yds from me, i was able to see and read the font on the printed poster on their door, looked like a usual A4 format page.
major difference is - it is an ultra wide lens, not the stock celestron tunnel vision. i used 9mm and it is, i think, quite OK. looking at it now i think that may be a 6mm would be even better. i was concerned that too much magnification there will be counterproductive, but, the image is pretty damn nice - the core mirrors and optics in the celestron body are very good.
from old thread:
For the
f6 80mm scope,
fl 480mm;
8mm = 60x, 12mm = 40x, 16mm = 30x, 20mm = 24x, 24mm = 20x.
For the
f5.4 100mm scope,
fl 540mm;
8mm = 68x, 12mm = 45x, 16mm = 34x, 20mm = 27x, 24mm = 23x.
View attachment 678648