Steve, I got these Nikons when Swedish kronor was 10% stronger to Yen then They're quite good to my eye, Vega is as pin sharp in the edge as in the center in 120ED, very good stray light control (Moon is invible outside field of view), scatter light on Jupiter is in level with 18mm BCO. very little latteral colour seen in daytime, clearly less than MaxVisions; very little rectilinear distortion, the slight barrel distorion is only seen in 17.5mm pointing at telepost in daytime. Angular Magnification distortion in these EP does make splitting doubles in the edge more difficult, this is none issue for me though since I prefer to observ on-axis where aberrations are minimum. The extra field is good for star-hopping, the distortion type (AMD) suit me better to match star patterns with star chart. 17.5mm SW has 26mm ER! it's quite smaller without the eye cup: Using 17.5SW without eye cup, you get the same floating effect which 28mmRKE is famed for, but its much easier to hold the view in Nikon. Edit: forgot to mention it, they're par-focal, and par-focal with Pentax XW too