Burgess 20x80mm LW
Big Binoculars are available from many manufacturers. Some of the most popular are the 80mm varieties that typically come in 11x, 16x and 20x. I find the 20x to be the most advantageous for astronomy. The larger image scale and darker sky background bring out more detail than their lower power counterparts do. Celestron has discontinued their standard 20x80 and now offers only the ‘deluxe’ version. Orion and others offer similar products.
Enter the new lightweight 20x80 from Burgess Optical. At just 3.5 pounds, it is the lightest 80mm. If you are steady enough these can be hand held for a short time.
Bill Burgess was kind enough to send me one of his new 20x80 lightweights for evaluation. The Binocular arrived safely, well packed and collimated. Upon opening the box, I was struck by the similarity between it and a 15x70 I had recently purchased for a friend- a 70mm on steroids. The body is rubber coated. Soft, tight fitting, objective and eyepiece covers are also provided. A nice surprise was the hard case – the 70mm came with a fabric case and I expected the same from this 80mm.
Optical testing and evaluation have been of interest to me since I looked through my first telescope (a prize out of a box of cereal that showed little more than could be seen with the naked eye). That was over 4 decades ago. My criteria have changed significantly over the years. Unlike telescope optics, a binocular does not need perfect optics as defined by the laws of physics. That is not to say that the optics can be of poor quality. The ability to evaluate optics in a practical sense takes time and experience. This is especially true for binoculars.
So just how good are the optics in the Burgess 20x80? In my opinion they are better than many of the big boys and, for the price, very good indeed! The edge of field does suffer from the standard amount of astigmatism but the entire Pleiades is nicely framed, sharp and contrasty. Alberio is a beautiful blue and gold and widely split. At full aperture, Saturn’s rings separate from the globe. Masked down to 40mm to reduce its brightness Saturn looks more like the view in a quality low power telescope than that of a binocular. The only other negative (at night- not visible in the daytime) is a slight vignetting of the upper edge of field that I find easy to overlook considering its otherwise excellent images.
Magnifying the primary image with an auxiliary scope shows acceptable levels of correction for spherical aberration and astigmatism – quite good in fact for such a large aperture high power binocular and commensurate with the visual checks already mentioned. Secondary color is well corrected. There is just a touch of blue surrounding the brightest stars. In the daytime, some off axis color is noted as well as a thin border of blue and green attributed to the eyepiece. With the binocular properly adjusted and the eye well centered, the view is excellent with only a trace of residual colors on the more trying objects.
From time to time I adjust and clean binoculars for a shop up north
– I just picked up a batch including a 15x70 Galileo and a 20x80
MegaView from Orion. The 15x70 is vended under several brand names with
minor differences in coatings, coverings and accessories. This goes for
the 20x80 as well. Performing the tests mentioned above revealed some
interesting comparisons. The 15x70’s tests were almost identical to the
Burgess 20x80 with perhaps a tad better color correction (as you would
expect from a lower power smaller aperture) and just a bit less sharpness
in one barrel than the Burgess. Here comes the surprise.
The Orion MegaView, which costs over three times as much as the
Burgess 20x80, had the worst optics! High power inspection showed the
cause. Both barrels exhibited very similar results: The intra/extra focal
magnified image showed excessive spherical aberration as well as much
greater residual color in the primary objective lenses.
Inside of focus, where the color differences were easiest to see,
the image of an artificial star was bright red on the outside and emerald
green on the inside. I would say this is almost an order of magnitude
greater than in the 15x70 and 20x80 Burgess. At normal magnifications,
images in the MegaView were noticeably soft and showed more color. Even
with their ‘fully multicoated’ optics, the MegaView’s contrast
suffered compared to the Burgess.
Submitted by Herb Teeuwe - Divide, CO