I'm a noob with an Orion Starblast 4.5, F4, 113mm aperture, 450mm focal length. I found it at a thrift store for $30 without eyepieces. So I bought a used svbony 68° eyepieces in 20mm and 9mm because I'm cheap. That gives me 22x and 50x magnification. I also got a Meade model 140 barlow to pump it up a bit. The eyepiece coatings look good. They're only multicoated so that means at least one lens surface has no anti-reflection coating.
I anticipated a poor performance with an F4 scope from what I've read in this forum. I tested in daylight first. Well, the 20mm was an OK performer. Not a flat field. There's just a hint of blackout at the very center that distorts the image as your eye moves around. I found myself shifting the object off center just to get a clearer view. The 68° AFOV is acceptable than I thought. Probably more than I needed. The 17mm eye relief is a welcome. Barlowing produced an image similar to the 9mm. The blackout diminished significantly if not disappeared. The eye relief didn't really extend as I anticipated. Night views was great. Makes searching easier but not much else to see at such low magnification. The moon looked pleasantly sharp. I can almost discern saturn's ring.
The 9mm in daylight was also OK. Sharp center and no blackouts. It kidney beans easily if the entire field is not in view. Your eye also have to remain centered. It states a 17mm eye relief but I feel it's shorter than that. The Expanse Clone equivalent states 15mm eye relief. My eye glasses hits the lens before the full field comes into view and the beans disappear. That didnt happen with the 20mm. Barlowing was a blur. The image was bigger but no additional resolution. A disappointment. I saw saturns ring for the first time so that was good. Mars was just a flared blob. The eye relief also did not extend with the barlow as anticipated.
I will adjust my review as I do more viewings in the coming days. I wonder if getting the 6mm is worthwhile.
Edited by bananas, 13 October 2018 - 01:55 AM.