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#1
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AFOV vs Aperture Poll
Here are the results of a "poll" that I initiated in the
middle of a thread with the dopey title "What's so Great about Tele Vue Eyepieces?" I was hoping to get some sense of the value that people place on a wide AFOV by presenting the following choice: Suppose you had to spend the rest of your life on a desert island with one of the following sets of equipment, which would you choose? * An 8-inch scope with a full set of 80-degree-AFOV EPs. * A 10-inch scope with a full set of 50-degree-AFOV EPs. I mentioned Plossls and Naglers specifically, but my real intention was to assume that all other things are equal except the apertures of the scopes and the AFOV of the EPs. Needless to say, this is not a realistic scenario. Nonetheless, the results are quite instructive; people fall into four camps: * One person (Jon Isaacs) refuses to take the bait; apples are apples, oranges are oranges, and he'll deal with the desert island when and if he has to. * Three people (Howard Lester, David Knisely, and me) after hemming, hawing, and qualifying, come down quite clearly on the side of aperture. From our point of view, AFOV is definitely a second-order issue, to be considered only after first-order issues like aperture. * Two people (Bill Meyers and Stephen Paul) come down quite clearly on the side of AFOV, citing in particular the esthetic benefits of a wide AFOV. * Two people (Axel and Bill Ferris) lean towards aperture but qualify this depending on the details of the circumstances, citing primarily the practical (rather than esthetic) benefits of a wide AFOV. I am not sure that I like my use of the term "esthetic" above; after all, one could argue that *all* visual observing is fundamentally driven by esthetics. Visual observing is not completely dead as a means of obtaining practical data, but it is at a pretty severe disadvantage compared to electronic imaging. It is also interesting that despite the relatively low value that I place on the esthetics of AFOV, I place a very high value on the esthetics of dark skies, as evidenced by my other thought experiment, where I choose lifelong exile under dark skies with 10x50 binoculars to a life under perpetual full Moon with a 12-inch scope. This is clearly a matter of esthetic preference, because by any reasonable measure, one can see *far* more with a 12-inch scope under full Moon than with 10x50 binoculars under a dark sky. - Tony Flanders |
#2
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AFOV vs Aperture Poll
Tony Flanders wrote:
* Three people (Howard Lester, David Knisely, and me) after hemming, hawing, and qualifying, come down quite clearly on the side of aperture. From our point of view, AFOV is definitely a second-order issue, to be considered only after first-order issues like aperture. Four, actually. I'm not sure why Google is refusing to archive my posts on this thread, since I don't put that particular header in my posts. BTW, I don't hem and haw--not on this issue, since I've given it some thought in the past in response to similar questions. Brian Tung The Astronomy Corner at http://astro.isi.edu/ Unofficial C5+ Home Page at http://astro.isi.edu/c5plus/ The PleiadAtlas Home Page at http://astro.isi.edu/pleiadatlas/ My Own Personal FAQ (SAA) at http://astro.isi.edu/reference/faq.txt |
#3
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AFOV vs Aperture Poll
Tony Flanders wrote:
* Three people (Howard Lester, David Knisely, and me) after hemming, hawing, and qualifying, come down quite clearly on the side of aperture. From our point of view, AFOV is definitely a second-order issue, to be considered only after first-order issues like aperture. Four, actually. I'm not sure why Google is refusing to archive my posts on this thread, since I don't put that particular header in my posts. BTW, I don't hem and haw--not on this issue, since I've given it some thought in the past in response to similar questions. Brian Tung The Astronomy Corner at http://astro.isi.edu/ Unofficial C5+ Home Page at http://astro.isi.edu/c5plus/ The PleiadAtlas Home Page at http://astro.isi.edu/pleiadatlas/ My Own Personal FAQ (SAA) at http://astro.isi.edu/reference/faq.txt |
#4
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AFOV vs Aperture Poll
In my youth (the early 1970s), 50 degrees *was* wide field. For a while
there, my best eyepiece was a Ramsden with a 30-degree field. I would choose an 8-inch with 20-mm-eye-relief eyepieces over a 10-inch with conventional eyepieces. And my preferred AFOV is about 60 to 65 degrees. Radians and Pentax XLs for me! |
#5
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AFOV vs Aperture Poll
In my youth (the early 1970s), 50 degrees *was* wide field. For a while
there, my best eyepiece was a Ramsden with a 30-degree field. I would choose an 8-inch with 20-mm-eye-relief eyepieces over a 10-inch with conventional eyepieces. And my preferred AFOV is about 60 to 65 degrees. Radians and Pentax XLs for me! |
#6
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AFOV vs Aperture Poll
Tony Flanders wrote:
It is also interesting that despite the relatively low value that I place on the esthetics of AFOV, I place a very high value on the esthetics of dark skies, as evidenced by my other thought experiment, where I choose lifelong exile under dark skies with 10x50 binoculars to a life under perpetual full Moon with a 12-inch scope. This is clearly a matter of esthetic preference, because by any reasonable measure, one can see *far* more with a 12-inch scope under full Moon than with 10x50 binoculars under a dark sky. Where lunar/planetary observing is concerned, the 12-inch under would obviously outperform a pair of 10x50 binocs, regardless of light pollution. But for deep-sky observing, dark and transparent skies are the key. Given the choice between the binocs under pristine skies and a 12-inch under heavily light-polluted skies, I'd take the binocs under dark skies without hesitation. And it wouldn't be a choice based on aesthetics. It would be based on the superior performance of the smaller aperture under truly dark skies. Regards, Bill Ferris "Cosmic Voyage: The Online Resource for Amateur Astronomers" URL: http://www.cosmic-voyage.net ============= Email: Remove "ic" from .comic above to respond |
#7
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AFOV vs Aperture Poll
Tony Flanders wrote:
It is also interesting that despite the relatively low value that I place on the esthetics of AFOV, I place a very high value on the esthetics of dark skies, as evidenced by my other thought experiment, where I choose lifelong exile under dark skies with 10x50 binoculars to a life under perpetual full Moon with a 12-inch scope. This is clearly a matter of esthetic preference, because by any reasonable measure, one can see *far* more with a 12-inch scope under full Moon than with 10x50 binoculars under a dark sky. Where lunar/planetary observing is concerned, the 12-inch under would obviously outperform a pair of 10x50 binocs, regardless of light pollution. But for deep-sky observing, dark and transparent skies are the key. Given the choice between the binocs under pristine skies and a 12-inch under heavily light-polluted skies, I'd take the binocs under dark skies without hesitation. And it wouldn't be a choice based on aesthetics. It would be based on the superior performance of the smaller aperture under truly dark skies. Regards, Bill Ferris "Cosmic Voyage: The Online Resource for Amateur Astronomers" URL: http://www.cosmic-voyage.net ============= Email: Remove "ic" from .comic above to respond |
#8
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AFOV vs Aperture Poll
"Bill Ferris" wrote in message
... Where lunar/planetary observing is concerned, the 12-inch under would obviously outperform a pair of 10x50 binocs, regardless of light pollution. But for deep-sky observing, dark and transparent skies are the key. Given the choice between the binocs under pristine skies and a 12-inch under heavily light-polluted skies, I'd take the binocs under dark skies without hesitation. And it wouldn't be a choice based on aesthetics. It would be based on the superior performance of the smaller aperture under truly dark skies. Amen! A few years ago, the tour guide at Kitt Peak was a little puzzled that instead of lining up inside the 16-inch dome, I was outside reclining on a boulder, using my 8x40 binoculars. But then I told him what I was observing... galaxies down to 9th mag. or more... and so forth... I can use a telescope back home. I can't see what I was seeing in those binoculars! (And boulders are handy too. We need one for the yard...) |
#9
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AFOV vs Aperture Poll
"Bill Ferris" wrote in message
... Where lunar/planetary observing is concerned, the 12-inch under would obviously outperform a pair of 10x50 binocs, regardless of light pollution. But for deep-sky observing, dark and transparent skies are the key. Given the choice between the binocs under pristine skies and a 12-inch under heavily light-polluted skies, I'd take the binocs under dark skies without hesitation. And it wouldn't be a choice based on aesthetics. It would be based on the superior performance of the smaller aperture under truly dark skies. Amen! A few years ago, the tour guide at Kitt Peak was a little puzzled that instead of lining up inside the 16-inch dome, I was outside reclining on a boulder, using my 8x40 binoculars. But then I told him what I was observing... galaxies down to 9th mag. or more... and so forth... I can use a telescope back home. I can't see what I was seeing in those binoculars! (And boulders are handy too. We need one for the yard...) |
#10
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AFOV vs Aperture Poll
Make it five. Desert Island... no light polution... dark skies... mmmm. I'll
take the aperture any day of the week and twice on Sunday. I remember when my kellner with a 40 degree field was a big step up. I can live with 50 degree fields and deeper limiting magnitude. Chris * Three people (Howard Lester, David Knisely, and me) after hemming, hawing, and qualifying, come down quite clearly on the side of aperture. From our point of view, AFOV is definitely a second-order issue, to be considered only after first-order issues like aperture. Four, actually. I'm not sure why Google is refusing to archive my posts on this thread, since I don't put that particular header in my posts. |
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