Orion/Vixen BT-80

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Brand and Model:Orion/Vixen BT-80
Price ($USD):$1000
Attributes:un-checked Waterproof un-checked Armored
Objective Lens Size:80 mm
Magnification:36 x
Prism Type:Erecting
Field of View:1.1 degrees
Eye Relief:0 mm
Near Focus:0 ft
Weight (lbs):11lbs. oz.
Dimensions (w/h/d):
Description:Binocular telescope.
45 degree interchangeable eyepieces
Supplied with 25mm Ortho eyepieces.

Tom Gross's Review of the BT-80
Cloudy Nights' BT-80 Review
Cloudy Nights' BT-80 Review 2

Vote Highlights Vote
Orion/Vixen BT-80
I recently purchased these second hand. They work extremely well. At f/11 you need to have low power eyepieces for wide field viewing, but they perform surprisingly well at up to ~ 100X. I've owned several pairs of giant binoculars including Myauchi BF100's, Apogee RA 88's and Oberwerk BT-100- 45's. These are easily the best performing of them all including the Myauchi's!

Overall Rating: 9
Weight: 1 (Unreliable Vote)
Link to this vote: http://www.excelsis.com/1.0/displayvote.php?voteid=453204

Orion/Vixen BT-80
I bought this binoscope some months ago, and I am rather satisfied with it. I use vixen lanthanum eyepieces. a pair of 40 mm yields 22.5x magnification with about a 1.85 degree field. There does not seem to be much vignetting. The field is very flat, with pinpoint star images accross the entire field. Deepsky like for instance M31 or M42 is stunning. The #d effect is really there and the difference while looking with one or two eyes is unbelievable. Although an 8 inch sct gives brighter views of many deep sky objects, the Bt-80 wins due to sharper more contrasty views. For deepsky I mostly use 22.5x and 45 x magnification, although the trapezium in M42 stands out very nicely at 75x and 100x. At these high magnifications the collimation of my pair of binoscope is still very good, images are nicely merged.
A word about the color dispersion of the achromats. On deep sky this is not visible, only at the brightest objects at 75x or 100x a violet haze is seen. These are for certain the best 80 mm binos that I have ever used.
How does it perform on planets:
Jupiter looks like a big 3D ball floating in space at 45x and 75x, although at 75x some colour is visible around the planet. Bands show many more details with two than with one eye. I think it can easily stand up against much larger single-eyed achromats. Once I have detected a nice shadow transit of Europe, and I am sure that in a perfect seeing moon transits should be detectable. Saturn is also very impressive, rings are clearly visible at 22x and at 75 x the cassini division shows at moments of steady seeing. The low surface brightness of saturn however screams for larger objectives.
The moon is wild at 3D, like flying over it and 100x yields amazing views with the whole moon in the field of view. In fact this is the first telescope through which the full moon looks very interesting, but only when viewed with two eyes.
As the scope is quite heavy and imprperly balanced, it needs a sturdy mount. I use a Vixen Custom-D altazimut mount with slow motions and counterweights.
In summary, this is fine 80 mm binoscope, which can be used up to 100x magnification, above which the image starts to degrade. I do not know if this is due to the achromats or due to the amici prisms.
advantages: very impressive 3D views of moon, planets and brighter deep sky objects
disadvantages: Only works well with very expensive eyepieces like the vixen lanthanums: many other eyepieces do not reach focus or simply do not fit into the slightly undersized helical focussers. Another disadvantage is the rather limited field of view due to the long effective focal length of 900 mm in combination with small amici prsims and 1.25 inch eyepiece holders.

Overall Rating: 8
Optics:8 Value:8
Weight: 1 (Unreliable Vote)
Link to this vote: http://www.excelsis.com/1.0/displayvote.php?voteid=136742

Orion/Vixen BT-80
The big Orions did not seem to compare well (at least to my eyes) with many other large but more expensive binoc's. Lots of color fringing, and sharpness/aberrations at the periphery would rule them out for all but the most non-critical viewing. Admittedly this was some years ago, and their quality may have improved since then, but they were about the same as the big Celestrons, didn't like them either.

Overall Rating: 7
Weight: 1 (Unreliable Vote)
Link to this vote: http://www.excelsis.com/1.0/displayvote.php?voteid=41917

>... but they were about the same as the big Celestrons, didn't like them either.

I think you confound them with the Vixen (Orion Megaview) 15/20/30x80 Binoculars, which show indeed lots of colors. 

Jens Stolpmann
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