Thanks Adrian & Morton. I'll need to get my hands on a binoviewer by the looks of things
Having a squizz through one I suppose is the best solution.
My greatest fear with such large assemblies of glass is the loss of precious light. I compared an 8mm LVW with my 9mm TMB Planetary II, & I saw fainter stars through my cheap TMB, AND the field was just as good. Slightly smaller AFOV, but nett same AFOV. If there was a 13mm TMB, I may not be having this problem