John, ol' Pard, re your " ... testing accepted 'facts,' such as the myth of 30mm scope tubes providing a brighter image," I have a wonderful old instrument for directly measuring the de facto brightness of a scope's image, if it'll help you test your scopes' brightnesses. It's a classic English SEI Photometer -- (Ansel Adams put me onto it, and though it was terribly expensive for a young biologist in the 1950s, I finally got one) -- a portable optical densitometer. It is, I believe, the original and still most accurate spot meter. The center spot in its wee telescope covers about one degree of angle (IIRC) and reads an amazingly wide range of brightnesses very minutely and accurately. (Clear down to the shadow under a piano keyboard in a dimly lit lounge, for example)
<br>
<br>I've rigged-up a long Weaver base, with the saddle parts of two Weaver rings, to mount atop a tripod and hold a subject scope aimed at a white card. Back-to-back readings with the photometer -- one through, one over or beside the scope -- give a direct comparison of the brightnesses seen by the unaided eye and through the scope.
<br>
<br>If it's worth a trip to Stevensville to try it, you're welcome. I'll even put you up overnight -- in somewhat less than regal comfort, unfortunately -- if a one-day trip won't be enough to get the job done. [406] 777-2878
