To All,
Using Tom Hole's method of measuring clear aperture in a binoviewer, I took my new Burgess binoviewer outside in the sun light with my digital calipers. (Sun light has become a rare thing here is Ohio recently)
Measuring the illuminated circle on the paper covering the eyepiece holders while pointing the binoviewer at the Sun, I found I had an illuminated circle approximately 21mm in diameter. Shifting the binoviewers back and forth I found I could see a slightly clipped area of the circle. This did not seem to have more than a 1mm incursion into the circle at its greatest depth.
Since this was just a rough quick measurement, holding the binoviewers in one hand and the digital caliper in the other hand, I believe we can safely say that the clear aperture of these binoviewers is between 21mm and 22mm. It would not be a perfect 22mm because of the clip outs anyway. 8O
Don Durbin
Denk IIs coming UPS tomorrow
Burgess BV125 Model C
Original 22mm BlackNights with Diopters
45mm Elite BlackNights with Diopters
Sieberts 1.3X OCA, Sieberts UltraBarlow, Sieberts Multimag OCA.
Denkmeier 2" SCT Star Diagonal
Stellarvue AT1010
Meade ETX90
Stellarvue 102APO
Celestron C9.25
Orion Atlas 8"
Meade 152ED
Using Tom Hole's method of measuring clear aperture in a binoviewer, I took my new Burgess binoviewer outside in the sun light with my digital calipers. (Sun light has become a rare thing here is Ohio recently)

Measuring the illuminated circle on the paper covering the eyepiece holders while pointing the binoviewer at the Sun, I found I had an illuminated circle approximately 21mm in diameter. Shifting the binoviewers back and forth I found I could see a slightly clipped area of the circle. This did not seem to have more than a 1mm incursion into the circle at its greatest depth.
Since this was just a rough quick measurement, holding the binoviewers in one hand and the digital caliper in the other hand, I believe we can safely say that the clear aperture of these binoviewers is between 21mm and 22mm. It would not be a perfect 22mm because of the clip outs anyway. 8O
Don Durbin
Denk IIs coming UPS tomorrow
Burgess BV125 Model C
Original 22mm BlackNights with Diopters
45mm Elite BlackNights with Diopters
Sieberts 1.3X OCA, Sieberts UltraBarlow, Sieberts Multimag OCA.
Denkmeier 2" SCT Star Diagonal
Stellarvue AT1010
Meade ETX90
Stellarvue 102APO
Celestron C9.25
Orion Atlas 8"
Meade 152ED