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Lawrence Sayre
Abbe Normal
Reged: 10/16/04
Posts: 4736
Loc: N.E. Ohio
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Re: Strange Results in Eyepiece FOV Comparisons
05/20/08 07:57 PM
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What possible harm would there be to anyone in having the manufacturers report the RFOV? Why does Baader feel it is important to report the RFOV? It is a simple, practical, and quite useful tool.
And as the original poster ascertained, AFOV's do not tell anyone what they will actually see, but rather only how far the eye will have to glance from side to side to see the REAL field that the eyepiece and telescope are presenting to the viewer. In his actual example, as regards the true field that he expected to see based on the apparent field, the AFOV was off by 12.7% in one direction for one eyepiece, and 4.9% in the other direction for another eyepiece, for a combined error of 17.6% in his simple yet futile attempt to use AFOV's to compare one eyepiece against another. With RFOV this error would be reduced to near zero.
All else being equal (regarding resolution from center to edge, contrast, transmission, color purity, etc...), if I had the option to see a real field of 77 degrees within an apparent field of 68 degrees, vs. seeing a real field of 77 degrees spread over an apparent field of 82 degrees, I would choose the former, since my eye would be able to take in the same real field of view far more comfortably, with less wandering of the eye required to absorb the exact same chunk of sky.
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My philosophy, in essence, is the concept of man as a moral being, with his own happiness as the moral purpose of his life, with productive achievement as his noblest activity, and reason as his only absolute.
Ayn Rand (in the appendix to 'Atlas Shrugged')
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