The 'floating in space malarky' has to do with the very long eye relief the 28mm RKE has, about as long as its focal length. This makes for a curious visual experience to see a sharp eyepiece image set upon a dark, blurry background. All eyepieces with very long eye relief show this effect. They are also coupled with an AFOV less than 52° as it requires a tight AFOV for this effect to be noticeable. A 65mm plossl I had also showed this effect, and the AFOV of this 2" eyepiece was around 38°.
The 28mm RKE is a curious beastie for this reason. Very few EPs have so much eye relief. The 65mm plossl I mentioned had ER of close to 50mm.
The combination of such long ER and the apparent 'floating' affect is not to everyone's liking. I too had a 28mm RKE, and I was fine with it, but another mate couldn't deal with it
Image quality wise, the RKE is a nice, modestly priced old technology EP that does very well in fast Newtonians. If you have a tight budget, it is a good option, though hard to come by. My only bone I have to pick with the new ones that are being produced is they have a very basic lens coating, not fully multi coated, and are priced higher than el-cheapo plossls that are actually more expensive to fabricate and are multi coated.
Note, the floating in space effect only happens with the 28mm RKE. All the other RKE focal lengths behave the same as plossls, less eye relief and smaller eye lens as the focal length shortens.
Alex.
