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Deep-sky binoviewer - contrast vs light loss

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#26 Astrojensen

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Posted 10 January 2014 - 05:16 PM

Hi Glenn

Exactly. A binoscope with 70mm objectives has the same performance on detection of threshold deep-sky objects as a 82mm telescope with a single eyepiece. And a 100mm scope with a binoviewer has the same performance as a 82mm scope with a single eyepiece, when it comes to detection of threshold deep-sky objects, because each eye sees the same amount of light as with a 70mm objective.

Thus, as I said: A 70mm binoscope has the same visual limiting magnitude as a 100mm scope (1.4x the aperture) with a binoviewer. They meet halfway, so to speak. The 70mm binoscope performs better than its aperture would suggest and the 100mm with bino performs a little worse.

To match the visual performance of a 10" binoscope, with a single scope with a binoviewer, one would need a 14", because splitting the light from the 14" in two gives each eye the equivalent amount of light a 10" delivers.


Clear skies!
Thomas, Denmark

#27 Hothersale

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Posted 10 January 2014 - 07:49 PM

I agree, Thomas. It is only necessary to factor in the summation effect when comparing bino-viewing to mono-viewing. Comparing binoculars to binoviewers, brightness is strictly a function of total aperture, making a 10" binocular and a 14" telescope roughly the same. (Of course, the 14" telescope would still have a resolution advantage over the 10" binoculars.)

It occurs to me that talking about the "summation effect" is a backward way of thinking about things. We observe the world with two eyes 99% of the time, but in astronomy we have accepted as normal the brightness deficit that our brains experience when observing with only one eye. In reality, mono-viewing offers a dimmed view of the universe.

#28 Chopin

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Posted 11 January 2014 - 08:02 AM

It occurs to me that talking about the "summation effect" is a backward way of thinking about things. We observe the world with two eyes 99% of the time, but in astronomy we have accepted as normal the brightness deficit that our brains experience when observing with only one eye. In reality, mono-viewing offers a dimmed view of the universe.


I have to say, this is the first time I've actually heard or read this statement in such context. It's simple and brilliant. I concur completely.

#29 GlennLeDrew

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Posted 11 January 2014 - 08:21 AM

That's what I've been 'preaching' for a while now; with a monoscope you're hobbling yourself, and a bino is really the natural instrument. I've essentially eschewed mono viewing, preferring to stick to even the smaller true binos rather than do the cyclopean squint. I've cone to really dislike the one-eyed view of anything. It so obviously lacks the 'presence' that Su desire.

To see (and hear this) in action, try this while watching the tube some time. Spend a little while with one eye and one ear covered then open them up again. The increased signal to noise offered by both your paired eyes and ears should be notable. This will be felt as a more 'definite' presence. Particularly if the screen and sound are on the dim side.

#30 Arizona-Ken

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Posted 11 January 2014 - 09:10 AM

"... cyclopean squint ..."

I like it. And, "cyclopean" is an actual word!

I am a big user of binoviewers, and do all of my deep sky work with a C11 and some EarthWins. As posted in this forum by many others numerous times, the more comfortable, natural use of two eyes makes it easier to spend more time with the view, actually allowing one to observe more.

And our brain, actually using information from two eyes as mother nature has us wired to do, gets more information from the view. However, although we can calculate all manner of optics, this improvement of using two eyes instead of one can probably not be quantified.

Arizona Ken






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