I have a 13mm t6 and this old 7mm .. I really like the 7 and find it is often
in the focuser .. its previous owner made the coment that it was one of
his most used and liked .
Arthur I used to suffer blackout badly .. my 27 pano was a woefull for a while , I folded down the eyecup and use my thumb and forefinger on the barrel to centre my eye around the eyelens and have not had a problem since .I got hold of a 27 mm pretoria recently and it was even worse
until I went the same way again .
The 7 and 13 have never been a problem because I tend to do this
anyway ,good luck
