Surprisingly good - Barska Blueline 10x40 Close Focus Monocular AA10320

This is a good piece of glass (plastic?) for the price and surprisingly clear. I haven't noticed any spherical aberration in the image. It is a little darker than I expected for a 40mm objective but it may just be tinting from the coatings. You have to find the 'sweet spot' to eliminate the chromatic aberration around the edges of dark objects against a bright background (or vice verse) - but at least the 'sweet spot' is there. There is just enough fuzziness that you can't read street signs at 600 yards but you unless you're TRYING to read street signs at 600 yards you'd never notice. This may sound pretty critical but I'm really just nit-picking, I'm actually impressed with this optic. Overall it seems to be good quality, time will tell if it stands up in the field. Surprisingly good for the price and definitely worth it.
Pros: decent optics, (relatively) compact, solid, seems to be well made, smooth mechanism, focuses close as claimed
Cons: not quite as bright as you'd expect from 40mm coated objective lens, ever so slightly out of focus at long range, need to find the 'sweet spot' for best viewing

This review was written in the old system and had content requirements that are different than reviews written today.