
Burgess Optical 25x100 Binoculars
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I’ve been
visually observing from East TN since the summer of 2008, with both
binoculars and telescopes. I purchased a pair of Apogee 25x100s a
little over a year ago, and decided to purchase another pair of
25x100s for a variety of reasons. I found a good price on a Burgess
Optical 25x100 here on the CN classifieds, so I picked them
up.
First off, the Apogee and Burgess binos are the exact same
body style and armoring. They appear to have been made in the same
factory. The main observable differences are:
1. The coatings
appear thicker/more colorful on the Apogee objectives.
2. The
Burgess pair uses BK7 prisms, light cutoff is clearly visible in the
diamond/45° turned square pattern in both eyepieces.
3. The
Burgess pair feels heavier (I don't have an adequate scale to measure
this), but there is no obvious reason - the externals and internals
look the same.
The case that the Burgess pair came with is
vinyl/pleather covered with a combo zipper/velcro closure and has
some padding and stiffness. You wouldn't want to drop them while
they're in this case, but it's good for transporting them for short
distances and it has a good shoulder strap attached to it. It is
inferior to the Apogee case (nylon/cloth) due to the inability to
zipper down the sides – this makes it a nightmare to insert and
remove the binoculars.
The objective lens covers fit
perfectly.
Now, for the lenses & prisms. The objective
lenses appear to be lightly multi-coated on both sides. They are a
light green/purple color. Same as the Apogee pair, the eyepieces
appear to be only lightly single coated to a light shade of blue. The
prisms are definitely BK7 due to the visible cutoff, and it appears
that they internal surfaces are lightly multicoated.
The
eyepieces are individual focus and are just the right stiffness and
have a pretty wide range of adjustment in my opinion, same as the
Apogees.
The stiffness of the tripod brace rod in the center
is the same as the Apogee pair and it is nice and stiff. The
stiffness of the IPD adjustment is very good as well - it doesn't
move at all between viewing sessions and transporting it back and
forth. The tightening mechanism for the tripod brace rod to tripod
head mount is pretty hefty, but you can't get a good enough amount of
tightness to prevent a little (not free, you have to push a little)
rocking of the binos on the brace rod. It's not a problem, though.
The collimation screws are inside of the binos, same as the
Apogees - you have to take the gold colored eyepiece covers off (2
screws) to get at them, and there are 3 per side, but some of them
appear to have been cranked on pretty hard as there is obvious usage
and what appears to be varnish or some sort of glue to hold them in
place. I've got pictures of the collimation screw locations for the
Apogees (same for these) in my review of the Apogee pair here:
http://www.cloudynights.com/item.php?item_id=2131
Now, on to visual
observations.
The stated FOV for these binos, printed on the
right eyepiece cover, is 157' @ 1000yds (or 3°). The measured
FOV, using the Apogee pair for comparison is exactly the same is as
the Apogees - 2.25°.
Images are sharp and clear in the
middle of the FOV, and are clear & sharp out to about 70%, then
drops off sharply to the edge (same with the Apogees). There is the
same amount of false color present on these binos as there is on the
Apogees. Maximum sharpness & clarity are centered in the center
of the FOV.
I've also measured magnification and aperture of
these binos using two homemade masks - 80mm & 70mm - over one
objective of the binoculars. Measured with a pair of inside calipers,
the results are:
100mm - 4.1mm exit pupil = 24.4x
80mm -
3.4-3.5mm exit pupil = 23.2x
70mm - 3.1mm exit pupil = 22.6x
So, it appears that the 100mm is masked down internally.
Averaging the 2 closest readings, I get a magnification of 22.9x, and
multiplying that by the original 4.1mm exit pupil, I get an actual
aperture of 93.9mm. These measurements were with the eyepiece cup off
so that the exit pupil measurement was taken right up against the
glass of the eyepiece.
IPD measured at 57-75mm, length is
15.25", and eye relief is ~10mm (4mm shorter than the Apogees -
the best views were with the eyepieces cups folded away).
Now,
for visual comparisons.
Saturn - rings observable in both,
but the Burgess pair exhibits some flaring on the left side
M81/82
- slightly brighter in the Burgess pair (compared at least 5 times)
M13 - same in both
M92 - same in both
M65/66 - same in
both
M57 - slightly brighter in the Apogees (compared at least 5
times)
One item of note - after a side by side comparison,
daytime views of the sky through the Apogee pair seems a little
yellow, whereas the view through the Burgess pair seems a little
blue. I've attached pics below to show this (the first two pics are
courtesy of the previous owner, Jim Rosenstock, used with his
permission – thanks, Jim). The pics of the tower (about 3800'
away) were taken afocal with a Kodak Z760.
Eyepieces:
Bottom:
Side
by side 1:
Side
by side 2:
Apogee
objectives:
Burgess
objectives:
Burgess
view, slightly blue:
Apogee
view, slightly yellow:
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