Which magnification is best

The final point to consider when looking at the magnification of binoculars is the Exit Pupil. This is what dictates how bright images will appear when viewing them through the binoculars. A higher number will indicate better viewing in low-light environments. For example, in low-light situations an exit pupil of 5mm would be greatly beneficial. The exit pupil will also impact on image clarity if the binoculars were to move or shake when held.

With everything considered, how does magnification fit in to this? Dividing the magnification by the objective lens diameter will determine the value of the Exit Pupil. Binoculars that offer an 8x magnification and an objective lens diameter of 32 will provide an Exit Pupil of 4mm.

This would provide an extremely clear image even in low-light conditions. Binoculars with a lower magnification power and objective lens will not take in as much light. Therefore, these would not be suitable for use in all environments and light conditions. Finding the correct balance for this will result in the highest possible image quality. Determining which magnification power can be tricky. There are many independent factors to consider that will define which magnification is best for you.

Both the 8x and 10x magnification zoom will provide great results and will be suitable for all occasions. Whether this is for birdwatching or general observation, this magnification range will be perfect for this. For those that are just starting out, a magnification power of 8 is ideal. This will provide you with the zoom necessary for all activities and provides a wide FOV. These level of magnification will also result in less distortion if the binoculars were to move during use.

However, for those that want the ability to have a more detailed examination, a magnification power of 10 is perfect. This is suitable for all users though will require a steady hand to ensure you receive the best results. In addition to this, the reduction in FOV makes this less accessible than binoculars with a smaller magnification.

By: Al Nagler July 17, 0. You can unsubscribe anytime. How high or low can you get your telescope magnification? The answers depend on many factors that combine to give each telescope a useful magnification range. This range is not fixed, however, and depends on the nature of eyesight, the telescope's aperture and optical design, atmospheric conditions, and even the type and size of the object looked at.

Consider the complete viewing experience: starlight passes through the atmosphere, through the telescope , and finally into your eyes. Each segment of the journey plays a role in determining the telescope magnification range to use on a given night. Let's take up the segments separately. Eyesight is an engineering marvel. Think about it: Our eyes have an automatic iris, automatic focus, an aspheric lens, a curved image surface, a chemical image intensifier, a windshield washer-wiper, and a lens cover, all as standard equipment.

And this is without mentioning the wonder of stereo vision! While our eyes are not perfectly color corrected, our brain processes out the errors. Other defects vary from individual to individual. Fortunately, the common ones can all be compensated when one uses a telescope. Among the most prevalent defects is astigmatism, which can be ameliorated with eyeglasses or by using only the small central area of our eye's pupil.

To see an example of this, make a diamond-shaped aperture by pressing your thumbs and forefingers together. The harder you push them together, the smaller the aperture will become.

Now place this opening close to your eye. You will probably see some improvement in resolution and depth of focus. You may look silly to your companions at the dinner table, but it's great for reading the menu when you forget your glasses. Those who suffer near- or farsightedness can simply remove their eyeglasses to use a telescope, since the instrument can be focused to compensate for either defect. Floaters, those bits of debris in our eyes, are mainly a problem when we use magnifications that produce very small exit pupils that accentuate their visibility.

There are several important factors to consider with telescope magnification: magnification, true field, apparent field, exit pupil, and resolution.

The first of these is telescope magnification , and by this I mean angular magnification. We see the universe in terms of angles.

To achieve low telescope magnification, use long-focal-length eyepieces. Telecompressor lenses can shorten the effective focal length of some telescopes, lowering the magnification of a given eyepiece used with that telescope. High telescope magnifications can be obtained by using short-focal-length eyepieces. Barlow lenses which can even be "stacked" allow a short-focal-length telescope to achieve absurdly high magnifications.

But beware: these high magnifications may not be what we want! The power, 2. A "fast" telescope implies a short focal length and a large field. Visually, well-made fast and slow telescopes of the same aperture have no difference in image brightness or resolution. The true field of a telescope is the amount of actual sky we see in the eyepiece. It is determined by the diameter of the field stop the ring inside the front of the eyepiece that defines the edge of the field and the focal length of the telescope.

Eyepieces of very long focus may use the inside edge of the barrel as a field stop. The in-side diameter of a typical 2-inch barrel is 1. Many eyepieces have field stops that are accessible for measurement by calipers. Others have field stops between the lens elements; such a stop's size cannot easily be used to determine the true field. Regardless, you can find the true field of any eyepiece-telescope combination by the star-drift method. Point the telescope at a star near the celestial equator and, with the drive turned off, time the passage of the star centrally across the field.

Since equatorial stars appear to move 15 arcminutes for each minute of time, you simply multiply the drift time in minutes of time by 15 to find the true field angle in arcminutes. A rough approximation to the true field is obtained by dividing the apparent field of the eyepiece by the telescope magnification. It's rough because eyepieces do not magnify linearly across the field, and a factor involving geometric "pincushion" distortion must be applied.

Needless to say, this is usually known only to the designer. So use the star drift to determine true field accurately. While the true field is the actual amount of sky you see through the telescope and eyepiece, the apparent field is the angle of sky that the eyepiece alone sees, and it is what the manufacturer lists with the eyepiece. If you want to know which of two eyepieces is likely to have a larger apparent field, hold one up to each eye as if you were looking through binoculars.

Position them so the field circles overlap, and it will be very clear which circle is larger. Exit pupil is the diameter of the beam coming out of the eyepiece. It determines where you place your eye to view the entire field.

You can calculate the exit pupil by dividing the diameter of the objective mirror or lens by the eyepiece magnification.

Indeed, binocular makers indirectly specify the exit pupil by specifying the magnification and the aperture. High magnifications produce small exit pupils, while low magnifications produce large ones. With very high magnifications and small exit pupils, images except for stars grow dim, atmospheric turbulence and shakiness in the telescope's mounting are much more noticeable, and "floaters" particles inside the eyeball can be annoying. On the other hand, one problem can arise from a large exit pupil.

If the telescope has a central obstruction, such as the diagonal mirror in a Newtonian or the secondary in a Schmidt-Cassegrain, it appears as a dark spot in the exit pupil with the same relative size that the secondary has to the objective. This shadow is mostly a problem during daytime viewing, when the eye's pupil is smaller. But it's worth noting, as this blockage falls at the center of the eye's pupil and obscures the portion of the eye that performs best.

Resolution can be defined in many ways. By tradition, telescope manufacturers use the Dawes limit as a specification. During the 19th century in England, Rev. There are two types of prisms, Porro prism and Roof prism. There are also Galilean and mini Porro type binoculars. These binoculars use a Porro prism developed by an Italian inventor.

It has excellent optical properties and enables a bright, sharp field of view from low to high magnifications. Dach means "roof" in German. Roof prisms are designed to be used in a straight line with the eyepiece lens and objective lens optical axis, making it possible to build lightweight, compact binoculars.

This is a simple structure that uses both convex and concave lenses and is featured in opera glasses. These binoculars can erect the image without the use of a prism. This type of binoculars has a simple lens structure that is relatively inexpensive while practical has a limited magnification of 4x.

The name comes from Galileo Galilei, who first looked at celestial objects with a telescope. This is a modification of the Porro prism type, which reverses the order of the eyepiece and objective lenses. It features superb optical performance, making a lightweight, compact design possible, however, because the objective lenses are placed on the inside of the eye width, this design is limited to small objective lenses with a diameter of about 15 to 25 mm. Centre focusing ring is used to adjust the focus simultaneously for both the left and right sides for quick focusing.

Some models also have a diopter adjustment ring for dealing with a visual acuity difference between the left and right eyes. If your browser's JavaScript is disabled, the message display and other operations may not work properly. Be sure to enable the JavaScript in your browser's settings if you want to view messages. T series Accessories.

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Choose binoculars for a specific purpose. Part names. Effective diameter of objective lens. Exit pupil diameter and relative brightness. In bright locations. In dark locations. Three fields of view for binoculars.