Such a question is asked by those who choose a spotting scope for the first time - for themselves or for someone close to them. Observation optics - is not yet the most common, but an unexpected and original type of gift. Application of a spotting scope will be found in any sphere, whether it be professional activity, a hobby or tourism.
In this article we will help you decide on your choice and discuss the most important features of this device.
What is a spotting scope?
A bird watching spotting scope is a kind of compact and portable spotting scope designed for observation of ground objects. Basically, spotting scopes are used to observe birds, animals, the environment and others.
What is the difference between a telescope and a spotting scope?
Spotting scopes have a smaller magnification, a wider field of view, are compact and lightweight. It is easy to carry, it has a rugged body, often waterproof, and the prisms used in the optical design provide a properly oriented image.
Telescopes, on the other hand, typically provide an inverted or mirror symmetrical image. Such an effect is not essential when observing stars and other celestial objects, but misdirected observation of wildlife is simply inappropriate. It is difficult to watch a bird when it seems to move to the right when it is observed through a telescope, but in fact, it flies to the left.
What to look for before buying
Although many of the parameters will be listed below, they cannot be limited to selecting a spy spotting scope. Pay attention to the impact resistance of the housing, protection against fogging. Besides, we recommend to pay attention to the presence of a tripod and convenient fastening for installation on a tripod, ergonomic design, presence of protective caps on a lens and an eyepiece.
However, it can be difficult for newcomers to choose the first scope: often they relate to the task... ...too responsible! Let's find out what to look for when selecting the device:
The most common values of spotting scope magnification are 15-60x. An increase less than 15x is considered useless; as such, an increase can well be provided by binoculars or monoculars at lower cost and weight. And magnification above 60x leads to a loss of image brightness, which is especially noticeable in low light conditions and a narrowing field of view. Thus, the most suitable value of magnification for bird watching will be the magnification of 20-40x, which will provide both a fairly bright image and a good field of view.
Objective lens size
The luminosity of the device depends on this parameter. The higher this value is, the better and brighter the image will be. During the day, you will not notice it, but at dusk and cloudy weather, this factor will be decisive. At present, manufacturers typically produce the visual spotting scopes with a diameter of 52 to 82 mm. Models with a diameter of 60-65 mm and 77-82 mm are widely distributed. The 80mm diameter lens collects 65% more light than the 60mm lens, which is important for high magnification and low-light conditions. It should also be noted that the larger the lens diameter, the higher the price, size and weight.
Exit pupil size
The brightness of the image is determined not only by the aperture of the spotting scope, but also by the output pupil. The diameter of the output pupil is the diameter of the light beam formed by the eyepiece and visible through it. To calculate the diameter of the exit pupil, divide the aperture of the observation tube by its magnification. Thus, the higher the magnification, the larger the diameter of the lens is required to produce a bright and clear image.
When you select a spotting scope, make sure that the output pupil diameter is at least 1.33mm because in low light conditions, spyglass tubes with an output pupil parameter less than the specified value will produce poor image quality, especially at higher magnifications.
Many spotting scopes are supplied with an eyepiece, although for some models of expensive high quality spotting scopes, such as Vixen, Swarowski, amongst others, you may need to purchase an eyepiece separately. The chosen eyepiece determines the magnification of the observation tube, the diameter of the exit pupil, removal of the exit pupil and the field of view. You can choose and buy an eyepiece with fixed or variable (zoom) magnification. Today, eyepieces with variable magnification (zoom) are of much better quality than they were a few years ago. Using eyepieces with variable magnification provides a more comfortable observation, because it is much easier and more convenient to first look at a remote object at a slight magnification, and later to look at details at higher magnification. However, it should be noted that eyepieces with variable magnification have a slightly narrower field of view than those with fixed magnification. The quality of the eyepiece lens and the design of the eyepiece also influence the quality of the resulting image, so choosing an eyepiece is just as important as choosing the spotting scope itself.
Field of view
The Linear Field of View (FOV) is calculated as the width of the visible area at a distance of 1000 yards or meters from the observer. The field of view can also be calculated in degrees, in which case it is called the angular field of view respectively. As a rule, the field of view narrows with increasing magnification. Usually a wider field of view is required to observe fast-moving objects.
Spotting scopes have the following optical designs: refractory and mirror-lens. Most models have a refractory optical design. The point is that although catadioptric (mirror-lens) spotting scope provide a clearer image than refractors (for the same parameters), they are much more expensive, but less robust and reliable than a refractor spotting scope.
There are several types of spotting scopes:
• Straight-eye" spotting scopes with a direct eyepiece (the eyepiece is on the same axis as the spotting scope body), often marked with the letter "S".
• Spotting scopes "angled" with an eyepiece at 45 degrees. (The eyepiece is located at an angle of 45 degrees to the spotting scope body), the letter "A" is used in the marking.
There is such a concept as the removal of the exit pupil - is the distance by which you can remove your eye from the eyepiece and still see throughout the field of view. Extendable eyecups, which increase the exit pupil removal, are very useful for people who wear glasses and even for a person with normal eyesight, will make observation more comfortable and reduce the strain on the eyes.
There are several designs of focusing mechanism: with one handle or with two handles.
• Single-handle systems provide the fastest but coarsest focusing.
• Focusing with two handles takes longer. One handle ensures coarse focus on the subject and the other provides fine focus adjustment.
This parameter determines the minimum distance from the observer at which a remote object should be located in order to be able to sharpen (focus) the image. Therefore, if you observe objects that are close to you, this parameter should not be very large.
In making your choice, look at the spotting scope body material and its tightness. Of course, a more robust housing is a metal housing. However, the plastic housing is lighter and easier to transport. The housing can also be rubberized to protect the spyglass tube from impacts and falls. Nitrogen filling is used for misting up the lenses in high quality tools. These spotting scopes are highly leakproof and are not afraid of sudden temperature changes.
A luminous coating applied to optical surfaces improves lens throughput by reducing the amount of reflected light. This way, the enlightened optics provide a brighter and clearer image. There are several types of lenses that can be coated:
• Single-layer coating on at least one of the lenses
• Single-layer illumination of all optical surfaces of glass/air
• Multilayer enlightenment of at least one lens
• Multilayer coating of all optical surfaces Glass-air
And the main thing is to remember that the quality of the image and the comfort of your observations depend on which one you choose the spotting scope, and, therefore, all your impressions from the observations!