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Bino viewers.

Discussion in 'Eyepieces, Barlows, and Filters' started by kevan hubbard, Jan 19, 2019.

Bino viewers.

Started by kevan hubbard on Jan 19, 2019 at 10:49 AM

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  1. kevan hubbard

    kevan hubbard Well-Known Member

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    Anyone got any ideas on the following? I was reading a recent debate on if small binoculars or monoculars where better of backpacking.one respondent claimed that only using one eye loses you 2 degrees of magnitude.no as I'm not an optician and don't really know how the human brain processes visual imput I can't say if this is true or false.from what this fellow is saying using a binocular over a monocular will gain you 2 magnitudes in visible light.it got me thinking about,if true,how this would work with telescope binoviewers? would a telescope with a binoviewer be able to see fainter objects than with a normal single eyepiece? unlike binoculars a binoviewer afixed telescope only has one light collector while a pair of binoculars has two. I may at some point try and test this theory as I have a pair of 8x25 binoculars and the monocular equivalent by the same manufacturer.to be honest I think it might be wrong as the brain merges the images but then they're factors like dominat eyes,etc.
     
  2. jgroub

    jgroub Well-Known Member

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    I can't answer your direct question about the magnitude gain from using both eyes. I can say that there is some light loss when using binoviewers versus one eyepiece. The prism that splits the light absorbs some of it, and there are a couple of other optical surfaces on each side of the BV that do the same. I would suspect that the cheaper BVs (Celestron, William, Arcturus) have more light loss than more expensive models.

    What you do gain from BVs is a pseudo-3D effect. Obviously, there is no parallax with BVs - you're still looking through one telescope. But the brain notes that both eyes are looking at the same thing (as opposed to one eye being closed), combines the image from both, and creates a 3D effect for you. There is no actual 3D, but it looks 3D.

    As for testing out the hypothesis, you don't even need the monocular. You've got binoculars. Look through them with both eyes. Now close one eye, compare and contrast the views.
     
  3. kevan hubbard

    kevan hubbard Well-Known Member

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    Yes I've tested perceived light both eyes then one closed.during daylight no noticable difference.at night it's hard to say especially as,like our hands and feet(guess ears too?),one eye is stronger than the other.when ursa major gets higher I will use the faint star,if I recall Ludwig's star(or some other germanic king?),that forms the triangle with mizar and alcor. I think it is just under the 9th magnitude and in a suburban setting is rather tricky to get in my 8x25 monocular although my 10x42 gets it no trouble,no I have the binocular version of the 8x25(opticron) and I'll see if they fare better.
     
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  4. Don Pensack

    Don Pensack Vendor

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    The faintest galaxies I've seen have all been with single eyepieces. I think binoviewers do dim the image compared to single eyepieces.
    BUT, many observers report improvements in contrast using two eyes. I cannot say I have. The opposite, in fact.

    Binoculars or binocular-scopes, on the other hand, have definite advantages over a single scope with a single eyepiece.
    I've seen the Horsehead in 6" binoculars, where the smallest aperture I've ever seen the Horsehead in using a single scope and eye is 10"
     
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  5. Gabby76

    Gabby76 Well-Known Member

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    I enjoy using the BV for general viewing but for planetary detail I prefer the single eyepiece.
     
  6. Ed D

    Ed D Well-Known Member

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    I can't tell you the exact magnitude differences, but I have used binoculars and see objects much brighter compared to my monocular of same aperture. It stands to reason because of the increased light gathering of the two objectives vs the single one of same diameter. As great as binoculars are, for my use I prefer a 50mm monocular.

    As for binoviewers, which I have used for many years now, they do definitely dim the image compared to single eyepieces. However, the loss of image brightness is not as great as one would assume, the brain summing what both eyes see. I prefer observing deep space with single eyepieces, and bright planets and the moon with binoviewers. The biggest advantage for me is that the binoviewers make lunar observations pleasant, even in my 10" Dob, and floaters become a non issue at high magnification. On planets I do see better detail with the binoviewer, probably because in one eye I see much more detail and the other eye sees a brighter image, the brain summing the visual information.

    Ed D
     
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