Final comments on this eyepiece...
23mm Aspheric 62 degree No-Name or Celestron
$9 (ebay) direct from China
Inexpensive construction. So cheap but not the worst I have see. Housing is a plastic material, top of housing is rubberized to protect eyeglasses, barrel is aluminum. Optics are in the housing so the threading and retaining rings are all plastic as well. There is no field stop so the barrel is used as the field stop. Overall a very light eyepiece.
This is a 1-2 design. The eye lens singlet is non-glass and aspheric. Based on reflection off the surface it is also coated. Edges are not blackened. However, this lens fits into a black retaining ring prior to insert into the housing.
The field lens glass doublet with a strongly convex field lens face and a lightly convex interior facing face. Edges are blackened.
For daytime use it provided a nicely sharp and high contrast view in an 80mm f/6.25 Apo. View was sharp across the field except for the region close to the field stop. Primary off-axis issue for daytime use appeared to be field curvature (from the eyepiece or the scope). Eye relief was generous and long enough that no contact with the eyepiece housing was necessary. AFOV, although not quantitatively measured, was compared to other eyepieces and was easily in the 60-62 degree range.
For daytime white light solar viewing I used a TSA-102 f/8 Apo with WO Binoviewers.
White light solar viewing was excellent. Sunspots were perfectly crisp and highly detailed. As good of a view in white light solar as with any other eyepiece of any quality level. Only issue was vignetting at edge of field in the f/8 scope, indistinct field stop due to use of barrel as field stop. With disk of sun in center of the FOV the entire solar disk was crisp and resolute. Crispness of the view only suffered in the outer most portion of the FOV nearer the field stop when the Sun drifted to the field stop.
For night time use used a TSA-102 f/8 Apo.
In the longer f/8 scope the field stop showed vignetting and a less than distinct edge. This was probably due to the eyepiece using the barrel for a field stop. I do not recall this behavior in the faster f/6.25 scope. But quite obvious in the f/8.
Eyepiece was very sharp with excellent apparent contrast in the central 75% of the FOV. At approximately 25% from the field stop very slight astigmatism and Field Curvature (FC) began. FC was dominant and stars could be refocused to nice points until the star reached perhaps 10-15% from the field stop. At that point astigmatism became the more predominant issue.
With Barlow (TV 2x, 2.8x Klee) the AFOV seemed to become a little restricted and again the off-axis remained vingnetted in appearance with an indistinct field stop. However, it provided very crisp and nicely contrasted views. Lunar viewing was superb.
As far as light artifacts only one was noted. When a bright object was right at the field stop there would be a reflect off a component that appeared as a light just outside the field stop. It was very minor though and not distracting. Would happen if a bright star was right at the field stop or the Moon was at the field stop. The interior FOV background remained dark with no light artifacts present throughout its use.
No lateral color was noted in any of the tests.
It is a $9 eyepiece so hard to fault anything for that price. Performance was actually incredible for the price and given only a 3 element eyepiece. If a field stop is inserted this would have been a much more pleasant eyepiece to use, with little faults. And if the AFOV were restricted to 55 degrees it's performance would have been excellent! So it has the potential with a little ATMing to be quite a find and also an excellent outreach eyepiece.
The use of plastic retaining rings and threads in the housing is of course the downfall for the eyepiece and will limit its life if disassembled too many times as stressing the threads will happen. As far as the non-glass eye lens, I am going to have no judgment on it as performance of the eyepiece in the central 75% of the FOV was excellent. Obviously the use of an aspheric allows this low lens count eyepiece to work exceedingly well. My only question would be on the longevity of the eye lens after continued cleaning. But if the coating used provides a hard enough surface, this may not be an issue.
Overall a very inexpensive build, with a matching price, but with performance well above its build and price characteristics. For $9, certainly fun to have one in the box