Telescopes can have multiple uses depending on their design. Refractors and Cassegrains can provide a "correct-image" view, so they can be used for daytime land viewing as well as astronomy. Reflectors render the image upside down so they are not recommended for daytime viewing. This is not an issue for astronomy, however, because there's no "right-side up" in space.
A measure of the enlargement of an object seen through an optical instrument. More specifically, it is a measure of the angle subtended by an image viewed with optical aid divided by the angle subtended by the same object without optical aid. Magnification is determined by dividing the focal length of the telescope (or binocular) by that of the eyepiece. Hence a telescope with a 1200mm focal length and an eyepiece of 40mm yields a magnification of 30x. The human eye is considered 1x magnification.
The optical diameter (also known as aperture), is the size of the telescope's main light collecting lens or mirror, measured in millimeters or inches. As the diameter increases, more light is collected and the resolution increases.
The field of view expressed as part of a 360-degree circle. Holding your pinky finger out at arms length is approximately 1-deg wide. To convert this to the linear measurement of "feet at a thousand yards", multiply by 52.5. For example, at 1000 yards distance, a 7-deg binocular will see a width of 367.5 feet (7 x 52.5)
The edge-to-edge angular diameter of the light emerging from the eyepiece as seen by the eye. It is an inherent specification for a given eyepiece type or design. The apparent field of view of an eyepiece is directly related to the true field of view seen through the telescope; for a given focal length eyepiece, the greater the eyepiece's apparent field of view, the greater area of sky will be seen.
The distance, measured in millimeters, between the observer's eye and the eyepiece lens in which the entire field of view remains visible. Eye relief varies with the optical design but generally increases with decreasing magnification. Long eye relief is advantageous for observers who wear glasses, as they don't have to put their eye directly on the eyepiece to see the entire field of view, nor do they have to remove their eyewear.
The diameter of the circle of light exiting the telescope eyepiece. It appears as a distinct disk when the telescope is pointed at a bright source like the Moon. Also known as the Ramsden disk, the exit pupil varies with both aperture and magnification.
The minimal distance at which a binocular and/or spotting scopes can attain focus. Near focus is an important quality for bird watchers and wildlife devotees who want to get as close as possible to their quarry.
Lenses are coated with an anti-reflective material to ensure that as little light as possible is reflected away, thus more gets to your eye. Good lenses are at least "fully coated," with a single layer of magnesium fluoride applied to each air-to-glass lens surface. Multiple layers of coatings are even more effective; the term "multi-coated" means one or more lens surfaces have multiple coatings. "Fully multi-coated" is superior because all lens surfaces are multiple-layer coated.
Mirror star diagonals are coated with a reflective material similar to telescope mirrors in order to reflect the light into the eyepiece. Standard aluminum coatings reflect between 88%-92%, and enhanced aluminum reflects 97%.
Dielectric coatings use a different process to deposit a coating that reflects 99% of the light. In addition to the higher reflectivity, Dielectric coatings are much more durable than aluminum coatings, so they last longer and can be cleaned with less risk of damage.
Porro Prisms:
A binocular prism system that contains two right-angle prisms in each barrel offset from one another, requiring that the objective lenses be spaced farther apart than the eyepieces. Optically, Porro prisms often perform better than their Roof prism counterparts.
Roof Prisms are a compact binocular prism system that allows the objective lenses to line up directly with the eyepieces and hence yields a more portable binocular. Roof prism binoculars lose slightly more light to reflections than Porro prism binoculars. High-quality roof prism binoculars compensate for this with special optical coatings.
The distance between the two pupils of an observer's eyes. Binoculars can be adjusted to accommodate variations in a person's interpupilary distance.
Focus style
Center focus
Waterproof
Yes
Tripod adaptable
Yes
Diopter adjustment
Yes
Weight
2.0 lbs.
Height
7.3 in.
Warranty
One year
Included Items:
5/21/09 2:26 PM
Orion 10x50 WorldView Waterproof Binoculars
Reviewer: Andrew Senske
These WorldView 10x50 are excellent
binoculars, and they're enjoyable both in
the day and at night. The difference
between these and a couple of 7x35s I
also own is really significant. For
example, I can see M81 with the 10x50s
but not with the 7x35s. Eye relief is
great. The included strap is decent with
a padded portion for your neck. The
case is also decent but it would be nice if
it were padded.
The only real problem I've noticed with
these is the fold-down eye-cups. When
you fold them down the caps no longer
fit, so you'll have to fold them back up
every time you use them if you want to
be able to replace the eyepiece caps
when you're finished. Judging from the
looks of the eyecups after just one fold I
don't think I'll be folding them for each
use. It appears that the rubber eyecups
won't last long if you fold them too
much. A simple solution would be to
include eyepiece caps that are big
enough to cover the eyepieces when the
eyecups are folded down. A better, more
pliable rubber material might be a good
solution also.
Other than the eyepiece cups and caps
issue, these binocs are really good.
Considering they're fully multi-coated
and waterproof, they're a great deal. I
ordered a second set for my dad who
was astounded when he looked through
them.
12/13/08 10:00 AM
Orion 10x50 WorldView Waterproof Binoculars
Reviewer: Tony D. Martin
I think the 10x50 worldview is the best
value for the money. It has a tight focus
that does not slip. The optical system is
superior to the other brands, (in this
price range).
7/15/08 7:53 PM
Orion 10x50 WorldView Waterproof Binoculars
Reviewer: Melvin Pritchard
I bought the World View binoculars
recently. They give clarity and crispness
to anything you focus on with them. I
looked at the first quarter moon with
them and was stunned by the view.
2/29/08 9:45 AM
Orion 10x50 WorldView Waterproof Binoculars
Reviewer: Maqurice Plummer
On receiving my binoculars I was
impressed at the quality workmanship
but even more so the clarity.
I haven't had a chance to use them for
my main objective, which is stargazing,
because we've got 2 ft. of snow on the
ground. Yet, I have used them for
general viewing and I very pleased with
them compared to my other two pair of
cheaper binoculars. I won't be using the
old ones much anymore!
2/29/08 9:33 AM
Orion 10x50 WorldView Waterproof Binoculars
Reviewer: Valente M. Alegria
The 10 x 50 Worldview Bonoculars were a
Christmas present for my son. They were
delivered on time. The price was fair,
and allowed me to give him a present
that he has been enjoying on a daily basis.
Thank You.
V.M.A.