NATIONAL GEOGRAPHIC 9676201 Explorer 10X42 Binoculars Instruction Manual
- June 6, 2024
- NATIONAL GEOGRAPHIC
Table of Contents
NATIONAL GEOGRAPHIC 9676201 Explorer 10X42 Binoculars Instruction Manual
General Warning
Risk of blindness
Never use this device to look directly at the sun or in the direct proximity
of the sun.
Doing so may result in a risk of blindness.
- Do not place the device, particularly the lenses, in direct sunlight. The concentration of light could cause a fire.
- Do not disassemble the device. In the event of a defect, please contact your dealer. The dealer will contact the Service Centre and can send the device in to be repaired, if necessary.
- Do not expose the device to high temperatures.
Privacy Protection
The binoculars are intended only for private use. Please heed the privacy of
other people. Do
not use them to look into apartments, for example.
Scope of delivery
Binoculars, Dust protection caps, Instruction Manual
List of Parts
- Centre axle
- Twist-up eyecups
- Dioptre adjustment
- Body of the binoculars
- Lens tube
- Central focussing wheel
- Eyepiece
- Objective lens
- Threaded tripod connection
- Image circle with correctly set eye distance
Eyepieces for spectacle wearers
Screw in the twist-up eyecups (2) to use the binoculars while wearing glasses.
If you are not wearing glasses, unscrew the eyecups to achieve the required
distance from your pupils.
Adjusting the eyepiece distance
The distance between your eyes differs between individuals. To achieve perfect
interaction between your eyes and the eyepieces of your binoculars, set the
angle at the centre of the binoculars (1) so that you see a circular image
(10). Note this setting for later use.
Adjusting the focus
Look through your binoculars with your right eye closed. Now adjust the image
for your left eye by turning the centre wheel (6) until it is sharp and clear.
Close your left eye and adjust the image for your right eye by turning the
dioptre ring (3) until it is also sharp and clear.
Mounting the binoculars on a tripod
Your binoculars have a threaded tripod connection (9) built in. The required
tripod adapter is available as an optional accessory (Art. No. 1916001). With
this accessory, you are able to mount your binoculars on all BRESSER tripods
with a DIN mounting thread (e.g. Art. No. 4922100).
Binoculars ABC
MAGNIFICATION
The magnification value always is mentioned first in the model name (e.g.
8×42). With a magnification of 8x, the observed object appears one-eighth of
the distance away that it really is.
OBJECTIVE DIAMETER
The lens pointing towards the object is called the objective lens. In the
model name (e.g. 8×42), the second number stands for the objective diameter in
millimeters. The objective lens diameter is an indicator of the amount of
light that can enter the binoculars.
An objective diameter of 20 mm is sufficient for observations during the day. In twilight conditions, an objective diameter of 50 mm or larger is recommended, as the lenses can gather much more of the remaining light.
TRANSMISSION
The value of the ability to let light pass through optical systems is called
transmission.
OCULAR
The ocular is on the side of a pair of binoculars pointing towards the eye and
is often composed of three to six single lenses that form an achromat. The
ocular is one of the factors that determines optical quality (i.e. color
fidelity, sharpness and image distortion).
EYEPIECE FOR SPECTACLE WEARERS
An eyepiece for spectacle wearers allows for a full field of view with and
without eyeglasses. Its main aim is the adjustment of the distance from the
eye to the ocular (eye relief). When an observer sees a circular image through
the binoculars, the eye relief is set correctly.
BINOCULAR
Optical systems with two oculars are called binocular (hence the name
binoculars).
MONOCULAR
Optical systems with one ocular are called monocular.
TWILIGHT OUTPUT
The twilight output number quantifies binocular visual performance and detail
visibility in twilight conditions.
Formula:
√Lens diameter x magnification
The result is evaluated purely mathematically and is only of interest when comparing differing types of binocular (e.g. 8×30, 7×50 and 10×50). The number calculated disregards binocular performance increase due to optical treatment, top-quality glass types and the like. See luminous intensity for more information.
DIOPTRIC COMPENSATION
In binoculars with centre wheel focusing, the right eyepiece can be adjusted.
This compensates for the user’s eyesight deficiencies. In models with single
eyepiece adjustment, both eyepieces can be turned, as they also serve to
adjust the focus.
RUBBER ARMOUR
Binoculars with rubber armour are advisable for rugged, professional uses. The
black or olive green rubber armour protects the instrument against splashing,
dropping and impacts. The armour on our instruments has fast colouring and is
proof against sunlight.
COLLIMATION (double image)
This term means the parallel alignment of both halves of a pair of binoculars.
If an instrument is subjected to any major impact or dropped, the prisms may
become misaligned, making the instrument out of collimation. Observation
through such an instrument yields double images, as the contours seem to the
observer to be displaced. Readjusting for eyesight can compensate minor
maladjustment of this kind. However, a headache may result if such an
instrument is used for any length of time. Such instruments should always be
sent in for repair.
LUMINOUS INTENSITY (general information)
The luminous intensity (LI) quantifies the brightness of a pair of binoculars.
Under normal circumstances, a 7×50 pair (LI 51) yields much greater intensity
than a 10×50 pair (LI 25). To exploit the greater intensity of 7x50s, the
user’s pupils must be dilated to the size of the instrument’s exit pupil [EP]
(in 7×50: 50/7 = EP 7.14). In people over age 50, the pupil often doesn’t
fully dilate. In such cases, the higher luminosity cannot be exploited.
LUMINOUS INTENSITY (geometric)
The geometric luminous intensity is the mathematical brightness value of a
pair of binoculars. Models with higher luminous intensity are especially
suited to observation at twilight.
Formula for calculating luminous intensity:
(Lens diameter / magnification)2
e.g. (50/10)2 = 5 x 5 = 25
This calculation disregards any features improving performance, such as BaK-4 prisms, multicoating or optical glass quality.
FIELD OF VIEW
This is understood to mean the visible image at a distance of 1,000 metres
from the object being observed. This measurement is usually given in metres.
If given as an angle, 1° = 17.5 m.
An instrument with a field of vision over 120 m/1,000 m is called ‘large
field’, and one with a field of vision over 140/1,000 m is ‘wide angle’. Wide
angle instruments are particularly suitable for viewing moving objects such as
footballs or horses.
TRIPOD CONNECTION
Many binoculars have a tripod thread built in. These binoculars can be screwed
onto a tripod using an adaptor, which guarantees a static image.
COATING
Normal optical lenses reflect part of the light falling on them.
This causes a loss of light and a reduction in contrast due to light scatter.
Coating the lenses by steaming a reflection-reducing mineral layer onto them
greatly reduces reflection and increases light transmission (permeability).
NOTES on cleaning
- Clean the eyepieces and lenses only with a soft, lint-free cloth, like a microfibre cloth. To avoid scratching the lenses, use only gentle pressure with the cleaning cloth.
- To remove more stubborn dirt, moisten the cleaning cloth with an eyeglass-cleaning solution and wipe the lenses gently.
- Protect the device from dust and moisture. After use, particularly in high humidity, let the device acclimatize for a short period of time, so that the residual moisture can dissipate before storing. Remove the dust cover and store it in the included bag during use.
DISPOSAL
- Dispose of the packaging materials properly, according to their type, such as paper or cardboard. Contact your local waste-disposal service or environmental authority for information on the proper disposal.
- Please take the current legal regulations into account when disposing of your device. You can get more information on the proper disposal from your local waste-disposal service or environmental authority.
WARRANTY & SERVICE
The regular guarantee period is 10 years and begins on the day of purchase.
You can consult the full guarantee terms and details of our services at:
www.bresser.de/warranty_terms.
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