I don't think I've ever used one, and the only ones that I know are the Baader Hyperion aspherics.

https://www.firstlightoptics.com/baader-planetarium/baader-hyperion-aspheric.html



I have no idea who the OEM is although they appear to be quite popular this side of the pond. They seem quite reasonably priced to me, but Baader products are much cheaper in Europe compared to the US as a rule.

You've probably already seen this Wiki entry: https://en.wikipedia.org/wiki/Aspheric_lens

I found this old thread at Crowdy Fights, it seems interesting:

https://www.cloudynights.com/topic/503147-vite-23m-aspheric/

 

They look interesting. I've seen pictures of similar EP's before.




http://www.dhgate.com/store/product/svbony-optional-lens-4mm-10mm-23mm-wide-angle/388567236.html

If it wasn't for the undercuts I'd consider ordering some myself. Sometimes cheap doesn't always equate with bad.



These Barsta 'Sky-Watcher UWA' EP's were under £40 apiece.



These are not small eyepieces and give surprisingly good orthoscopic - like 58° views. They are possibly similar to TMB's.



The undercut isn't a problem as the weight of the eyepiece helps with insertion/extraction. I'm guessing they aren't flocked and they suffer from some ghosting and EOF shadows/reflections. They also don't Barlow well (drawtube Smyth lens cell). The 7mm one in the top row replaced two borked 7mm TeleVue DeLites I had to return. A DeLite costs five times the price of one SW UWA. Admittedly the DeLites are virtually perfect (when they aren't borked) but I got a hell of a lot of use out of these Barsta eyepieces with my 130mm Newtonian for lunar/planetary viewing last year. Apart from some slight ghosting/EOF reflections they give views virtually identical to Kasai orthoscopics.

So, it will be interesting to see what these inexpensive aspherics are like. I'll see if I can find any closer to home. Depending on the scope you're using (f/r) you don't necessarily have to pay stupid money for eyepieces. Which can't be a bad thing.

 

I have the 23mm Vite Asperhics. I bought a pair for binoviewing for 18 bucks. For 18 bucks, they ain't bad. Pretty good, actually. But don't be misled - my understanding is that one of the lens elements is most definitely made out of plastic - and that it's molded as opposed to ground. This obviously results in the ridiculously low price of nine dollars an eyepiece.

Like I said, they're decent enough, and work well in my binoviewer. They are the equivalent of $50 eyepieces in my opinion. I wrote up my experience with them on my blog, here:

https://jgroub.wordpress.com/2016/0...ty-pretty-pretty-good/?frame-nonce=c573e3109e