For the price of the diagonal, it’s good quality and worked for the public outreach I needed it for.
I was not sure what to expect. I felt my current diagonal which was manufactured in 1984 and came with my Celestron C8 may have some image issues. I decided to get this diagonal after reading favorable reviews on it. My visual viewing using this diagonal is very nice, a little brighter and better contrast than my vintage Celestron.
Only have used once, but seems truly 'flat', bright. and a good value! J
When I read the reviews, they said it had a compression ring, but the description didn't indicate that. I ordered it as I thought it would be a good deal even if it didn't have one. Well, it does and for a very nice price. Works perfectly for my purpose.
The optics seem pretty good, but disappointed that the mirror housing is plastic. I would not have purchased had I know it was plastic construction (to be clear, the barrels are NOT plastic).
This diagonal is great for the price. I had the chance to take it out and compare it side by side in the same scope (meade infinity 90) on the same objects with the 90 degree 'correct image' diagonal that came with the meade scope. It was no contest. The TPO was sharper and brighter by alot over the stock meade diagonal. It was like taking wax paper off the objective! This came as a big relief because I was starting to think that the scope's objective lens was defective. I'll keep the stock diagonal for daytime viewing as it's fine for that, but for viewing the night time sky, this TPO represent a fantastic value. Not only is it clear and bright but being a mirror it doesn't introduce any extra false color like a prism can in a fast system like my scope. Also it uses a brass retaining clamp to attach the eyepiece instead of set screws so your eyepiece barrels won't get marred and scratched. All for $29.95 shipped! So far I've looked at Saturn, Jupiter, and the Lagoon Nebula with it and all looked so much better than before. I could barely make out the Lagoon with the old diagonal at all, but not a problem with the TPO. I HIGHLY RECOMMEND this diagonal for anyone who needs an inexpensive 1.25 inch diagonal but still wants quality.