Comparison Carbon 25-75x60 WP vs Praktica Hydan 20-60x60 WA

The magnification of the image provided by a telescope. Roughly speaking, this parameter describes how many times the object seen in the eyepiece of the pipe will be larger than when viewed from the same distance with the naked eye.

Multiplicity — the first number (numbers) in the digital marking of optical instruments: for example, the designation 25-75x50 corresponds to a multiplicity from 25x to 75x. Note that most modern telescopes have variable (adjustable) magnification. This allows you to choose the mode of operation depending on the situation: to search for the desired object, it is more convenient to reduce the magnification, providing a wide field of view, and having found it, increase the magnification and examine in detail. However in some models, to change the magnification, you need to replace the eyepiece (see "Replacement eyepiece").

High magnification, on the one hand, makes the tube "long-range" and makes it easy to examine small objects at considerable distances. On the other hand, the angle of view decreases in this case, which makes it difficult to observe moving objects and even aim the optics at the target. In addition, with an increase in the magnification, the diameter of the exit pupil also decreases (see below) and the aperture ratio of the tube; you can compensate for this moment by increasing the lens, but this accordingly affects the price. So it makes sense to specifically look for powerful optics with a high degree of ma...gnification only when such capabilities are fundamentally important.

The field of view of the telescope at a distance of 1 km to the objects under consideration, the so-called "linear field of view". In fact, this is the width (diameter) of the space that falls into the field of view when observed from a distance of 1 km.

This parameter is widely used in the characteristics of telescopes along with the angular field of view (see below): the linear field of view data is more visual and closer to practice, it allows you to evaluate the capabilities of a telescope without resorting to special calculations.

For models of variable magnification (the majority of them), the linear field of view is indicated in the form of two numbers — for the minimum and for the maximum magnification.

Angle of view provided by a telescope.

If you draw two lines from the centre of the lens to two opposite points along the edges of the field of view of the pipe, the angle between these lines will correspond to the angular field of view. Accordingly, the larger the angle, the wider the field of view; however, individual items in it will look smaller. Conversely, an increase in magnification is inevitably associated with a decrease in the viewing angle. And since most modern telescopes have a variable magnification, the angular field of view is also variable, and in the characteristics this indicator is indicated in the form of two numbers — for the minimum and for the maximum magnification.

The smallest distance to the object under consideration at which the telescope is able to fully focus on it — that is, the minimum distance at which the image in the eyepiece will remain clear.

Spotting scopes were originally designed for viewing distant objects, so focus problems can occur if the distance is too small. Thus, manufacturers indicate this parameter in the characteristics. However, even in the most powerful and "long-range" models, the minimum focus distance is about 25 m — at this distance, the naked eye is often enough. Therefore, you should pay attention to this parameter only in cases where the ability to work normally close is of fundamental importance — for example, if the pipe is used at a shooting range, where the distance to the targets can be different, including pretty small.

Removal of the exit pupil of a telescope.

About the exit pupil itself, see above. Here we note that the offset is such a distance from the eyepiece lens to the observer's eye, at which the size of the visible image from the lens corresponds to the visible size of the eyepiece lens. In other words, the observed "image" in this case occupies the entire space of the eyepiece, without vignetting (darkening at the edges) and without "spreading" beyond the edges of the eyepiece. In this case, the overall image quality will be the best.

When looking down the pipe with the naked eye, the observer usually has no problem getting into the offset distance, and this parameter can be ignored. Problems can arise if the user wears glasses and the diopter adjustment (see above) is not sufficient to comfortably view without glasses. In such cases, it is desirable to use models with eye relief of at least 15 mm: although such a distance will not provide the highest image quality when viewed with glasses, it will allow using the device without any special difficulties. However, in modern telescopes, this parameter can reach 18 mm or even more.

Also note that eye relief may decrease somewhat with increasing magnification; in such cases, two numbers are indicated in the characteristics, corresponding to the removal at the minimum and at the maximum magnification.

The location of the eyepiece relative to the body (more precisely, relative to the optical axis) of the tube.

— Direct. In this case, the eyepiece is directed parallel to the optical axis of the tube — in other words, it "looks" in the same direction as the lens. In this case, the eyepiece can be directly on the optical axis or above it. The direct arrangement is convenient especially in those cases when the tube is used without a tripod and is held in the hands. It is well suited for observations from a shelter (for example, during hunting or wildlife research) — the observer does not need to rise above the body of the tube to look into the eyepiece. Also, this option is easier for novice users who have not previously dealt with optical instruments — it is more convenient to point the pipe at the target. In addition, when the eyepiece is located on the same axis as the lens, prisms can be dispensed with, which simplifies the design (although this arrangement in itself does not mean the absence of prisms).

— Under 45°. An eyepiece bent upwards by 45° relative to the optical axis of the tube. In many situations, this arrangement is more convenient for the observer. For example, it allows you to comfortably use a relatively low tripod (whereas a tube with a straight eyepiece must be placed at eye level, that is, either look for a high tripod or squat to the level of the eyepiece). In add...ition, for similar reasons, curved eyepieces are more convenient when observing objects above the horizon and celestial bodies. The disadvantage of this design is the unequivocal need to use Porro prisms (see "Prism type"), which can affect the cost. In addition, for a person without experience, aiming a curved pipe at the desired object can, out of habit, be quite a difficult task.

The presence of additional protection against impacts in the design of the spyglass body.

Any case is able to withstand impacts to a certain extent, however, this feature is indicated only for those models in which additional means of protection against impacts are specially provided — soft shock-absorbing material of the case (for example, rubber), elastic inserts, special lens mounts, etc. The specific degree of impact resistance of such a telescope can be different, this point should be clarified according to the manufacturer's documentation. However, usually, shock protection implies the ability to normally endure a fall from a height of at least a metre onto a flat hard surface.

The presence of a cover in the scope of delivery of a telescope.

The soft cover protects the device primarily from dirt, scratches and sudden changes in temperature; it can hardly be considered a serious protection against bumps and falls, however, in addition to such a case, a hard case is sometimes provided in the kit. Instead of a case, you can use impromptu packaging, but a complete case is usually more convenient. It fits perfectly with the “native” telescope, often has additional space for accessories (cleaning kit, interchangeable eyepieces, etc.), moreover, many covers can be left on even during use — just unfasten the fasteners on the side of the lens , eyepiece and tripod mount. Also note that the design usually provides for handles, straps and other devices that allow you to easily carry the device.

Material and general construction of the telescope housing.

Most modern models use rubberized cases, in which a solid base (metal or durable polycarbonate) is covered with rubber. This provides not only strength, but also increased shock resistance — even in the case when shock resistance as such (see above) is not claimed in the characteristics. In premium models, magnesium alloy cases are found — it is characterized by high strength combined with low weight.

A separate category are the Galilean pipes (see above) — they are usually produced in a "retro" design and use appropriate materials, such as copper and a high-quality leatherette cover.