Digital Binocular
Why Use a Digital Binocular?
Normally, when you go hiking or bird watching, you might take a high end digital camera or expensive binoculars. Instead, take an inexpensive digital binoculars camera and capture the moment while you enjoy the beauty of nature.
Integrated Digital Camera binoculars not only bring objects closer, binoculars digital camera let you take digital photo pictures, and, with many models, capture video, that you can share with friends, send to relatives, and keep a memory for years to come.
We offer the most complete selection of binocular cameras, and we make it easy to select the right model by different levels. Our binoculars with camera are great for birding and traveling - you can take, save, print, and share close-up digital photos.
Our higher end camera binoculars are great if you take a lot of pictures and want to print them or capture video with your digital binoculars. These digital binoculars with cameras are awesome for action sports, concerts, nature studies, industrial site inspection, or security and investigation applications.
Magnification: The ratio of the focal length of the eyepiece divided into the focal length of the objective gives the linear magnifying power of binoculars (sometimes expressed as "diameters"). A magnification of factor 7, for example, produces an image as if one were 7 times closer to the object. The amount of magnification depends upon the application the binoculars are designed for. Hand-held binoculars have lower magnifications so they will be less susceptible to shaking. A larger magnification leads to a smaller field of view.
Objective Diameter: The diameter of the objective lens determines how much light can be gathered to form an image. It is usually expressed in millimeters.
It is customary to categorize binoculars by the magnification × the objective diameter; e.g. 7×50.
Exit Pupil: Binoculars concentrate the light gathered by the objective into a beam, the exit pupil, whose diameter is the objective diameter divided by the magnifying power. For maximum effective light-gathering and brightest image, the exit pupil should equal the diameter of the fully dilated iris of the human eye—about 7 mm, reducing with age. Light gathered by a larger exit pupil is wasted. For daytime use an exit pupil of 3 mm—matching the eye's contracted pupil—is sufficient. However, a larger exit pupil makes alignment of the eye easier and avoids dark vignetting intruding from the edges.
Field of View: The field of view of binoculars is determined by its optical design. It is usually notated in a linear value, such as how many feet (meters) in width will be seen at 1,000 yards (or 1,000 m), or in an angular value of how many degrees can be viewed.
Eye Relief: - Eye relief is the distance from the rear eyepiece lens to where the image is formed. It determines the distance the observer must position his or her eye behind the eyepiece in order to see an unvignetted image. The longer the focal length of the eyepiece, the greater the eye relief. Binoculars may have eye relief ranging from few millimeters to 2.5 centimeters or more. Eye relief can be particularly important for eyeglass wearers. The eye of an eyeglass wearer is typically further from the eye piece which necessitates a longer eye relief in order to still see the entire field of view. Binoculars with short eye relief can also be hard to use in instances where it is difficult to hold them steady.
Focusing:
Ease and sharpness of focusing are important factors to consider when choosing a binocular or scope. There are several factors to consider when evaluating focusing. Most optics use a focus knob that you turn with one finger while looking through the optic. As a general rule, the knob should make one full revolution of travel from one extent to the other.
Diopter Adjustment:
Most binoculars have a diopter adjustment to allow the two barrels to be set at sharp focus for both eyes simultaneously. It is a critical part of setting your binoculars to match your individual eye strengths. The adjustment is only on one of the two barrels so that you can bring it to equal adjustment with the other. Since one of your two eyes is often a little stronger or focuses a little different than the other it is very important to make this adjustment. The adjustment should be done the first time you use a binocular and then checked every so often.
The diopter adjustment ring is usually located on the right eyepiece so it can be adjusted. Some of the newer models have incorporated it into the center focusing wheel and you must pull out the focusing wheel to make the diopter adjustments. The diopter adjustment method will be explained in the documentation. The adjustment should not be sloppy and should maintain its setting so you don't have to continually readjust it.
Close Focus:
Close focus refers to how close you can bring an image into sharp focus. It is usually specified or can be easily checked. It is an important part of choosing a binocular or a scope, particularly if it is ever used to take photos. It may seem that anything closer than about 15 feet doesn’t require a binocular view... this is not true. Birds may come in much closer than this, or you may simply wish to examine details of plumage in greater detail. You may also want to examine other things like butterflies, reptiles, flowers, etc. and close-focusing optics are advantageous in such situations.
A 6 to 8-ft close focus is an advantage in a binocular not only to focus on small close objects, but also because it gives you the ability to move beyond sharp focus in both directions while focusing. This helps to get a very sharp view. Traditionally, as magnification increases, the minimum close focal distance also increases. This generally holds true though there are now mid and high-end binoculars that close focus to 5-8 feet even at 10x or 10.5x magnification. Still, if you choose a high magnification binocular you may have to compromise your ability to close focus. Even some high-end optics may not close focus any closer than 15-16 feet, which is something of a limitation in our view... Any “close focus” longer than this is a handicap.
Lens Coating:
Since binoculars have many air-to-glass surfaces, with light lost at every surface, optical coatings can significantly affect their image quality. When light strikes an interface between two materials of different refractive index (e.g., at an air-glass interface), some of the light is transmitted, some reflected. In any sort of image-forming optical instrument (telescope, camera, microscope, etc.), ideally no light should be reflected; instead of forming an image, light which reaches the viewer after being reflected is distributed in the field of view, and reduces the contrast between the true image and the background. Reflection can be reduced, but not eliminated, by applying optical coatings to interfaces. Each time light enters or leaves a piece of glass; about 5% is reflected back. This "lost" light bounces around inside the binoculars, making the image hazy and hard to see. Lens coatings effectively lower reflection losses, which finally results in a brighter and sharper image. For example, 8x40 binoculars with good optical coatings will yield a brighter image than uncoated 8x50 binoculars. Light can also be reflected from the interior of the instrument, but it is simple to minimize this to negligible proportions. Contrast is also improved by good coating due to the partial elimination of internal reflections.
A classic lens-coating material is magnesium fluoride; it reduces reflections from 5% to 1%. Modern lens coatings consist of complex multi-layers and reflect only 0.25% or less to yield an image with maximum brightness and natural colors. For roof-prisms, anti-phase shifting coatings are sometimes used which significantly improve contrast. The presence of a coating is typically denoted on binoculars by the following terms:
- coated optics: one or more surfaces coated.
- fully coated: all air-to-glass surfaces coated. Plastic lenses, however, if used, may not be coated.
- multi-coated: one or more surfaces are multi-layer coated.
- fully multi-coated: all air-to-glass surfaces are multi-layer coated.
Phase-corrected prism coating and dielectric prism coating are recent effective techniques for reducing reflections.
There two major prism utilized in the digital binocular nowadays.
- Porro Prism System
Porro Prism Design
Named after Italian optician Ignazio Porro who patented this image erecting system in 1854 and later refined by makers like Carl Zeiss in the 1890's, binoculars of this type use a Porro prism in a double prism Z-shaped configuration to erect the image. This feature results in binoculars that are wide, with objective lenses that are well separated but offset from the eyepieces. Porro prism designs have the added benefit of folding the optical path so that the physical length of the binoculars is less than the focal length of the objective and wider spacing of the objectives gives better sensation of depth.
- Roof Prism System
Roof Prism Design
Binoculars using Roof Prisms may have appeared as early as the 1880s in a design by Achille Victor Emile Daubresse. Most roof prism binoculars use either the Abbe-Koenig prism (named after Ernst Karl Abbe and Albert Koenig and patented by Carl Zeiss in 1905) or Schmidt-Pechan prism (invented in 1899) designs to erect the image and fold the optical path. They are narrower, more compact, and more expensive than those that use Porro prisms. They have objective lenses that are approximately in line with the eyepieces.
- Porro vs. Roof Prisms
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Porro Prism |
Roof Prism |
Aside from the difference in price and portability noted above these two designs have effects on reflections and brightness. Porro-prism binoculars will inherently produce an intrinsically brighter image than roof-prism binoculars of the same magnification, objective size, and optical quality, as less light is absorbed along the optical path.
Prism Glass:
Two different classes are used to designate glass quality: Bak-4 and Bk-7. Bk-7 is the standard quality for glass in binoculars. It is cost-effective to manufacture and therefore more popular for simple binoculars. Bak-4 is cleaner and more transparent and is reportedly the best binocular grade glass on the market. Bak-4 quality is achieved through a complicated and time consuming manufacturing process.
Focus Range: Due to the optical properties of the lenses, only objects within a certain range of distances from the binocular will be reproduced clearly. The process of adjusting this range is known as changing the focus.
Image Sensor Type: An image sensor is a device that converts a visual image to an electric signal. It is used chiefly in digital cameras and other imaging devices. It is usually an array of charge-coupled devices (CCD) or CMOS sensors such as active-pixel sensors.
Today, most digital cameras use either a CCD images sensor or a CMOS sensor. Both types of sensor accomplish the same task of capturing light and converting it into electrical signals.
A CCD is an analog device. When light strikes the chip it is held as a small electrical charge in each photo sensor. The charges are converted to voltage one pixel at a time as they are read from the chip. Additional circuitry in the camera converts the voltage into digital information.
A CMOS chip is a type of active pixel sensor made using the CMOS semiconductor process. Extra circuitry next to each photo sensor converts the light energy to a voltage. Additional circuitry on the chip converts the voltage to digital data.
Neither technology has a clear advantage in image quality. CMOS can potentially be implemented with fewer components, use less power and provide data faster than CCDs. CCD is a more mature technology and is in most respects the equal of CMOS.
Pixels: Pixels are the tiny squares of color-similar to dots on a newspaper photograph or grains on a photographic print-that make up a digital image. The higher the pixel count, the higher the photographic resolution. A megapixel (MP) equals one million pixels.
Interpolation: Interpolation is a method of increasing the number of pixels in an image after it is photographed. The pixels actually captured by the camera’s sensor are rapidly analyzed by software that creates and adds new similar pixels to the photo file. Some Bushnell imaging optics provide user options for higher interpolated resolution settings, but all specifications are listed at the true pixel count of the digital sensor, not an artificially inflated number.
Lens Aperture: In optics, an aperture is a hole or an opening through which light is admitted. More specifically, the aperture of an optical system is the opening that determines the cone angle of a bundle of rays that come to a focus in the image plane. The aperture stop of a photographic lens can be adjusted to control the amount of light reaching the film or image sensor. In combination with variation of shutter speed, the aperture size will regulate the film's degree of exposure to light. Typically, a fast shutter speed will require a larger aperture to ensure sufficient light exposure, and a slow shutter speed will require a smaller aperture to avoid excessive exposure.
Diagram of decreasing aperture sizes (increasing f-numbers) for "full stop" increments (factor of two aperture area per stop)
Color Depth: Color depth is a computer graphics term describing the number of bits used to represent the color of a single pixel in a bitmapped image or video frame buffer. This concept is also known as bits per pixel (bpp), particularly when specified along with the number of bits used. Higher color depth gives a broader range of distinct colors.
# 1-bit color (21 = 2 colors) monochrome, often black and white
# 24-bit color (224 = 16 million colors)
Exposure Value (EV):
Exposure value (EV) denotes all combinations of camera shutter speed and relative aperture that give the same exposure. The concept was developed in Germany in the 1950s, in attempt to simplify choosing among combinations of equivalent camera settings. Exposure value also is used to indicate an interval on the photographic exposure scale, with 1 EV corresponding to a standard power-of-2 exposure step, commonly referred to as a “stop.”
Exposure value was originally indicated by the quantity symbol Ev; this symbol continues to be used in ISO standards, but the acronym EV is now more common elsewhere.
Although all camera settings with the same exposure value nominally give the same exposure, they do not necessarily give the same picture. The exposure time (“shutter speed”) determines the amount of motion blur, as illustrated by the two images at the right, and the relative aperture determines the depth of field.
Exposure times, in seconds, for various exposure values and f-numbers
Image Compression: In addition to high and low resolution settings, many digital cameras also provide user options for selecting the “Quality”, or amount of jpeg file compression that is applied when photos are stored in memory. Higher “quality” settings use less compression, but take up more storage space.
Digital zoom: Digital zoom is a method of decreasing (narrowing) the apparent angle of view of a digital photographic or video image. Digital zoom is accomplished by cropping an image down to a centered area with the same aspect ratio as the original, and usually also interpolating the result back up to the pixel dimensions of the original. It is accomplished electronically, without any adjustment of the camera's optics, and no optical resolution is gained in the process.
Flash Memory: Flash memory is non-volatile computer memory that can be electrically erased and reprogrammed. It is a technology that is primarily used in memory cards, and USB flash drives (thumb drives, handy drive, memory stick, flash stick, jump drive) for general storage and transfer of data between computers and other digital products. It is a specific type of EEPROM that is erased and programmed in large blocks; in early flash the entire chip had to be erased at once. Flash memory costs far less than byte-programmable EEPROM and therefore has become the dominant technology wherever a significant amount of non-volatile, solid-state storage is needed. Examples of applications include PDAs and laptop computers, digital audio players, digital cameras and mobile phones. It has also gained some popularity in the game console market, where it is often used instead of EEPROMs or battery-powered static RAM (SRAM) for game save data.
Flash memory is non-volatile, which means that it does not need power to maintain the information stored in the chip. In addition, flash memory offers fast read access times (although not as fast as volatile DRAM memory used for main memory in PCs) and better kinetic shock resistance than hard disks. These characteristics explain the popularity of flash memory for applications such as storage on battery-powered devices. Another feature of flash memory is that when packaged in a "memory card", it is enormously durable, being able to withstand intense pressure, extremes of temperature and immersion in water.
USB Mass Storage: Cameras with USB Mass Storage don’t need a driver for Windows 2000/SP. When you connect the camera to your PC, it will automatically be identified as a new “Removable Disk”, just as if it were an external hard drive. Your photo files stored in a folder on this “Disk”, and can be copied or moved to the location of your choice or opened directly from the camera within your photo software.
White Balance: The reason that pictures turn out with a yellow/orange cast in incandescent (tungsten) lighting and bluish in fluorescent lighting is because light has a color temperature. A low color temperature shifts light toward the red; a high color temperature shifts light toward the blue. Different light sources emit light at different color temperatures, and thus the color cast.
In digital photography, we can simply tell the image sensor to do that color shift for us. In our camera system, there are size white balance model, which are Auto, Daylight, Cloudy, Fluorescent and Tungsten.