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Q1.Which is better, a binocular
or spotting scopes?
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Both eyes are used to look through a binocular while one eye is used to look through a spotting scope.
Generally, spotting scopes have a much higher magnification than binoculars, so far away images appear larger.
But a better three-dimentional image can be expected from binoculars, and they are easier to handle and have better portability.
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Q2. What
is magnification ? |
Magnification describes
how many times closer an image appears. Magnification
is also called gPowerh and is abbreviated by the symbol
gXh. A magnification of 20 (20 power) means that an
object appears twenty times closer than you would see
it with the naked eye.
When looking through an optic with a magnification
of 20, an object at a distance of
100 yards /meters appears
to be only 5 yards/meters away. |
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Q3.What is
the actual field of view (angle of view) ? |
Actual field of view is
the view when looking through an optical device indicated
by the angle from the center of the objective lens. An
optical device with a of wide angle of view makes it easier
to find an object. In general it is more difficult to
find an object with an optical device with a higher magnification.
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Q4.What is
a field of view at 1000mi1000yds) ? |
Field of View (FOV) is
the width in yards/meters that can be seen at 1,000 yards/meters.
FOV equals the real angle of view x 52.4f. Every degree
of real angle of view can see 52.4f at 1,000 yards/meters.
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Q5.What is
objective lens diameter ? |
The measurement in
mm of the diameter of the objective lens of an optic.
As the diameter of the objective lens increases,
the optic will have better light gathering and higher
resolution. |
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Q6.What is
an exit pupil and a relative brightness ? |
Exit pupil is the bright
circle that is visible when the ocular lens is viewed
at a distance of about 25pi10inchj with the objective lens facing towards
a bright background or light source.
The larger the exit pupil, the brighter the image will
be under low-light conditions.
Exit pupil = Objective lens diameter Magnification
Relative brightness is a number used to compare the brightness
of binoculars or spotting scopes of similar magnification.
The larger the relative brightness number, the brighter
the image.
Relative Brightness = Exit Pupil 2
(or Exit Pupil size in mm, multiplied by itself).
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Q7.What is
resolution ? |
Resolution, or ultimate
sharpness, is the measure of the ability of a spotting
scope or binocular to distinguish fine details. Optical
glass is at its sharpest in the center, while resolution
decreases toward the edges in relationship to the quality
level of the lens. Larger objective lenses (with quality
as a constant) tend to improve resolution. This is because
they have a larger amount of sharp, center objective lens
area, as opposed to the amount of lesser sharpness at
the edge of the lens surface. |
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Q8.What
is minimum focus distance ? |
The closest
distance to an object that the binocular/spotting scope
will focus sharply. |
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Q9.What
is eye relief ? |
Eye relief is the
distance, measured in mm, between the eyepiece lens to
where the exit pupil is actually positioned in space (where
the pupil of the eye must be positioned for a full view).
A long eye relief makes observing for long periods of
time easy and tireless. |
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Q10.What
is multi-coating ? |
When light enters a lens
or prism, light is reflected from their surface at a rate
of about 4%. This reflection diminished the brightness
of the optic and causes flare or ghosting.
By coating the surface of the lens, the amount of reflection
can be minimized, decreasing flare and ghosting.
Different Types of Coatings:
coated optics: one or more surfaces coated.
fully coated: all air-to-glass surfaces coated.
multi-coated: one or more surfaces are multi-layer coated.
fully multi-coated: all air-to-glass surfaces are multi-layer
coated.
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Mono-layer Coating |
Multi-layer Coating |
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Q11. What
are the benefits of a gas filled optic? |
Spotting
scopes and binoculars are used in all types of weather,
so it is important to protect the instrument from
moisture. To keep the inside dry and keep moisture
from penetrating from the outside all of the air is
purged form the inside of the optic and replaced with
nitrogen gas.
The nitrogen gas prevents moisture from entering the scope
and keeps the inside dry.
| yCautionz *If condensation
appears on the optic, it is important to
wipe the moisture from the optic immediately. Failure to wipe moisture from the optic might
stain or promote the growth of mold or rust.
*In extremely high temperatures, materials
that keep the optic airtight (rubber rings,
oil, etc.)
might degrade and the airtightness may be
compromised. |
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Q12. What
is the difference between Achromat and Apochromat? |
* Achromat
An Achromat lens system compensates the wavelength differences
of two colors to diminish chromatic aberration.
For observation the two colors usually compensated are
blue and red, and for photography, purple and red.
An achromat diminishes chromatic aberration so that only
a little remains.
* Apochromat
An Apochromat lens system compensates the wavelength
differences of three colors or more. For example,
an apochromat system is designed to make purple, green
and red focus at the same point so that chromatic
aberration is significantly reduced. It has become
standard to use Fluorite Crystal, or a kind of XD (ED) lens for this
type of lens system.
yCautionz
The above are general explanations and differ among
optics manufacturers.
Recent refraction telescopes are called apochromat
when Fluorite or XD (ED) lenses are used and achromat
when other lens materials are used. |
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Q13.What
is needed to attach a digital camera to a spotting scope?
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Q14.Is it
possible to attach a video camera to a spotting scope? |
Yes, it is possible
to attach a video camera to a spotting scope in the same
way as a digital camera. |
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Q15. Which
spotting scopes can be used for digiscoping? |
The spotting scopes
listed below can be used for digiscoping.
* Note : Other manufacturers spotting scopes can not be
used.
ETSN-880(Ó88mm) series
ETSN-770(Ó77mm) series
ETSN-820M/TSN-820(Ó82mm) series
ETSN-1,2,3,4(Ó77mm)
ETSN-660iÓ66mmjseries
ETSN-600iÓ60mmjseries
ETS-610iÓ60mmjseries |
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Q16. What
is the focal length of the digiscope system? |
The focal length of
a digiscope system can be found using the following equation:
Focal Length = Focal Length of the Digital Camera x Magnification
of the eyepiece. |
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Q17.What
is the collimation method? |
The method of taking
photographs through a digital camera that is attached
to the eyepiece of a spotting scope is called the collimation
menthod. Collimate means the aligning of the optical axis
of the optical system.
Usually, we look through a telescope/spotting scope through
the eyepiece with our eye. When the human eye is replaced
by a digital camera to look through the eyepiece to take
a photograph, it is called the collimation method. |
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Q18.Why
does vignetting occur? |
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Q19.Is it
possible to attach a digital SLR camera to a spotting
scope? |
Yes, it is possible
to attach a digital SLR to the spotting scope with a Photo
Attachment and Camera Mount.
Kowa offers a variety of camera mounts for various makes
of cameras. ( Click
here for more information.) |
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Q20.Where to buy?/How to buy? |
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