I tested the 20mm Optimus against the 21mm Ethos. Looking through both eyepieces at a white wall reveals that the blue fringing at the field stop is identical to the Ethos in every way. It’s virtually a perfect clone, having a smaller barrel diameter due to the -1mm focal length difference. I did some research and found that even a 1mm difference is noticeable in brightness. 102-T Raptor, the Optimus is as sharp as the Ethos. I started with the double cluster. Both eyepieces exhibited atomically sharp stars. The Ethos shows slightly brighter stars on every object, probably because of longer focal length. Same with all clusters such as Hyades, Pleiades, M35, etc. Next came the 7” Mak. It’s really a shame that there are no more American made 7” Maksutov OTAs being made, that I know of. Saturn is as bright with both eyepieces and equally sharp and slightly more magnification with the Optimus. The Optimus has slightly better contrast on planets compared to the Ethos. Again the Ethos is slightly brighter but by such a tiny amount. Contrast wins here for sure. The 12” Dob was next. Starting with the veil and an OIII filter the Ethos was not noticeably brighter. The Optimus however showed blacker space which made the contrast better. M13 is easy with the propeller easily visible with no effort. Both eyepieces showed identical sharpness. Additionally, in fast scopes such as my 80mm Lunt Ha and the 102-T Raptor, the stars in the outer field of view show clear signs of being out of focus due to the aggressive field curvature. Using Harry Sieberts newly redesigned .6 reducer in the diagonal completely removes this effect equally in both the Optimus and Ethos. The stars are super sharp at the field stop. The Optimus appears to be a far better value at half the price of the Ethos. Its smaller barrel diameter means I can use it way easier for binoviewing. I think I will buy another. It’s hard to describe a 100 degree binoviewer experience at low power. Nothing compares. And the real difference between the eyepieces comes down to contrast or brightness. Slightly better brightness for twice the price or better contrast for half the price. For people such as myself that does everything astronomy (traditional visual astronomy, astrophotography, spectroscopy, etc), I have many eyepieces and the differences I can see most people might not notice.

Today was the first time I used it on my 18" Dob I thought I was looking through the cupola on the ISS. Fantastic eyepiece. Very helpful when star hopping to an elusive stellar object. Excellent service, quick on time delivery, properly packed to arrive undamaged. Highly recommend this company. Job well done, Thank You

I've been using this eyepiece in a 10" dob w/ focal length of 1250mm for a few weeks now, and it has been outstanding. I used it to upgrade away from a 2" 30mm plossl, and it has been worth every penny. While the plossl has a decent viewing area for its level of magnification, the Stellarvue 20MM Optimus gives me a slight increase in magnification and a much wider area to view when studying the stars and other celestial objects in the sky. Star clusters and nebulae are very clear on clear nights (the views of M35 and M42 are both very vivid in this eyepiece) , and with this wide viewing area I can observe for longer before having to realign the scope as the the sky moves. I will probably get something a little higher magnification for strict planetary viewing, but as a 'swiss army knife' eyepiece that can be used to do a lot of things the 20mm seems to be it for my scope. Well worth the cost.

Wonderful eyepiece with my 90mm Raptor.

Used it on my 90 mm Raptor. Great combo.

Best view ever out of my SV 102 T Apo refractor. Very easy to look through and very bright and sharp right to the edge. Definitely easier to look through than the Teleview Ethos 21mm that I have tested in the past.

I really enjoy this eyepiece. It feels like I’m inserted in space when using it with my scopes. Very sharp stars to the edge and such a great FOV to experience.

I wanted an eyepiece in this focal range for my Stellarvue SVX125D and I'm very happy with this purchase. The crispness of the image across the entire field of view is just remarkable. When I set my telescope up for observing, this is the first eyepiece I insert. Every bit as well made as the 6mm Delos and 35mm Panoptic that I also use. Another great value by the Stellarvue team!

I needed an eyepiece in this focal range for my Stellarvue scopes, an SCT and a 16" dob. I had a chance to evaluate an Ethos 20 and a Nagler 22 and I decided to go with the Optimus 20mm. The Optimus was wonderful in the dob, excellent in the SCT and is the main go to eyepiece in my SV130ED. I've used it for about 5 months. The fit and finish seem to be on par with my Ethos 13.I am very happy with the purchase and would do it again.