Quote: I wonder what it would be like to use a 120mm or 150mm short FL Achro with a bino-viewer.
In some ways it's all the advantages of a scope and giant binocs at the same time, though binoviewers do have some inherent disadvantages of their own
that is true, focus issues and more light loss. I wonder what a 150mm F5 w/BV would equate to in the binocular world.
Quote:So a 120mm scope with a binoviewer is like a 85mm binocular.
First and foremost observing love: naked eye.
Last but not least, telescopes.
And I sometimes dabble with cameras.
Milton Wilcox R.I.P
Quote: Yes, but with one critical caveat -- the binoviewer's exit pupils are 1.4 times wider than the binoculars. That's why binoviewers can never take the place of binoculars for viewing at ultra-low magnifications.
Consider the classic 7x50 binoculars. They have 7mm exit pupils, matching the nominal size of most young people's eyes. To achieve the same light throughput with a binoviewer, you'd need a 70mm scope. But a 70mm scope at 7x yields a 10mm exit pupil, much wider than *any* person's eyes can take in. For most people, a 70mm scope would actually deliver no more light at 7X than a 50mm scope. So the total light entering your eyes from a 7x70 scope with binoviewer is actually only half what you get from 7x50 binoculars.
Put another way, 50mm binoculars are better for viewing at 7X than any single-objective telescope can possibly be.
How about 10x50 binoculars versus a binoviewer on a 10x70 scope -- still assuming that your own pupils open to 7mm? The binoculars are *still* better, even in this case. That's because the outer part of most people's lenses has lousy optical quality. The reason your pupils close down in bright light isn't just to protect your retinas -- it's also to reduce the inherent optical aberrations of your eye, just as stopping down a 50mm f/1.4 photo lens to f/2 almost always yields far superior results.
Michael Gilmer - Member of the Meteoritical Society & Collector of Falling Stars.
☄ ⒼⒶⓁⒶⒸⓉⒾⒸ ⓈⓉⓄⓃⒺ - www.galactic-stone.com
Quote:Indeed,Which begs the question - are there any BV units available that accept 2" eyepieces or have a CA>27mm? People with wide-set eyes might be able to use a 2" BV.
TMB 175/F8 APO on CGE Astreya 102/F6,5 APO Astreya 76/F6 APO 152/F5,9 BINOSCOPE in progress 120/F5 BINOSCOPE 76/F6 APO BINOSCOPE in progress 10X50 APM binocular 3-6mm N Zoom,9mm NT6, ETHOS 6,8,2X13,17mm,2X 22mm NT4,2X Meade SWA 24,5mm,2X BW optik 30mm http://zdravko.spricer.com/
Quote:Siebert Black KnightBasic 40mm CA 2" BV sells for $1795.Premium 45mm clear aperture 2" BV costs $2000.Adjustable diopters extra, minimum $120 for one side.2" to 1.25" adapters, cause you won't always use 2" eps. $60 each.Optical Correctors extra. $159$ to $299.No eyepieces included.So total cost is $2200 to $2600, before eyepieces.Current waiting list for both is 1 year.
Quote: Another issue that I can see with a 2" binoviewer is weight. a 2" diagonal, 2" binoviewer body and two 2" eyepieces is a lot of weight. (not counting nosepieces, filters, etc) Such a load would require a premium, heavy-duty focuser that would also add a substantial amount of $$$ to the equation.
Regards and clear skies,
Richard Entwistle, Hong Kong.
ETX125 OTA, SV90TBV, & PST scopes
Celestron AVX Mount
Pentax PF-80ED,Meade 102ED APO,Orion EON 72,120ST Apex 127,C6 XLT,C6R,C9.25,XT10 ,Celestron Regal 100 F-ED, CT152 Zeiss 7x42 FL,Canon 10x42L IS WP,15x50 IS 12x36 IS II , Pentax 8x32 ED Garrett Optical 28x110 HD-WP Signature Series Oberwerk BT-80 45, Apogee RA-88-SA Denk II Power x Switch binoviewer w/13mm Ethos, 20mm Pentax XW's, 20mm Widescan III's. 21mm Ethos,17mm Ethos, 22mm Nagler, 40mm Pentax XW, 14mm Pentax XL, 5.2mm Pentax XL, 8-24mm Pentax XL Zoom, 31mm Axiom LX
Quote: when you mean shorter tube, are you meaning something shorter than F5, or are you referring to something else? Shorter tube means you take a tube and cut 3 or 4 inches off it. Note I have corrected my original post regarding the operation of the OCS - brain fade on my part.Milt