Comparison National Geographic Biolux 40x-800x with Adapter vs National Geographic 40x-640x with Adapter

The range of magnifications provided by the device is from minimum to maximum.

The magnification of the microscope is calculated by the formula "the magnification of the eyepiece is multiplied by the magnification of the objective." For example, a 20x objective with a 10x eyepiece will give a magnification of 10*20 = 200x. Modern microscopes can be equipped with multi-objective turrets, zoom lenses (see below) and interchangeable eyepieces — so that in most models the magnification can be adjusted. This allows you to adjust the device to different situations: when you need to consider small details, a high degree of magnification is used, but to expand the field of view, the magnification must be reduced.

Detailed recommendations on optimal multiplicities for different tasks can be found in special sources. Here we note that many manufacturers go to the trick and indicate the maximum value of the magnification by the degree of magnification achieved with an additional Barlow lens. Such a lens can indeed give a serious increase in magnification, but it is not a fact that the image will turn out to be of high quality; for more details, see "Complete set".

— Zoom lens. Lens with variable magnification. Such optics allow you to smoothly change the overall magnification of the microscope within certain limits, without changing the objective/eyepiece and without even looking up from observations. On the other hand, zoom lenses are more complicated and more expensive than constant magnification optics. Therefore, they are mainly used in stereoscopic microscopes (see "Type"): in the repair, assembly and other tasks for which such devices are used, the ability to smoothly adjust the multiplicity is extremely useful.

— magnification factor. The magnification provided by the lens. This parameter, along with the magnification of the eyepiece, affects the overall magnification of the device (see above). Most biological microscopes (see "Type") are equipped with several different magnification objectives on the turret; this allows you to adjust the degree of magnification as desired by the user. The standard magnification options for such lenses are 4x, 10x, 40x, 100x.

— Achromat. One of the varieties of colour correction used in lenses. The need for colour correction is due to the fact that light of different colours is refracted differently by lenses, and without additional measures, the image in the microscope would be blurred with iridescent stains. Achromatic is one of the simplest types of colour correction; in such optics, colour distortions in yellow and green are corrected.... Achromatic lenses have simple design and low cost. However the image quality in them is far from perfect: such a lens gives a clear image only in the centre of the image, the width of the sharpness zone is about a third of the total width of the field of view, and red-blue streaks may appear along the edges of the image. However, this is quite enough for general acquaintance, initial training, and often for more serious tasks.

— Planachromat. An improved and improved version of achromatic lenses (see above). Plan achromats provide additional correction of the field curvature, due to which the area of a clearly visible image in such lenses is at least 2/3 of the total width of the field of view, and often even more. It is these lenses that are recommended for serious study and professional use.

— Rim diameter. The size of the thread used to mount the lens. A larger bore usually means a wider lens, which means higher aperture and better image quality. On the other hand, the large size affects the dimensions, weight and cost of optics. In modern microscopes, diameters from 20 to 35 mm are mainly found. Knowing the size of the thread, you can purchase replacement or spare lenses for the device.

— Monocular. An eyepiece with a single lens that can only be viewed with one eye. For obvious reasons, it is only used in biological microscopes (see "Type"). The advantages of monoculars are primarily smaller size and cost than other varieties; in addition, they do not require adjustment for interpupillary distance. On the other hand, constantly looking into the eyepiece with one eye is tiring, so this option is poorly suited for situations where you have to look into the microscope often and for a long time.

— Binocular. Dual eyepiece that can be viewed with both eyes at once. Note that such optics are used not only in stereomicroscopes, originally intended for viewing an object through two lenses (see "Type"), but also in biological microscopes with one lens. The fact is that looking into an optical device with two eyes is much more convenient than with one, while the eyes are less loaded and fatigue does not occur so quickly. Therefore, for serious tasks associated with frequent use of a microscope, binoculars (or trinoculars, see below) are the best option. Such optics cost more than monocular, but this is offset by ease of use.

— Trinocular. A kind of binocular (see the relevant paragraph), supplemented by a third optical channel for a special camera-video eyepiece. Such a camera is usually connected to a PC or laptop; by installing it in the soc...ket for the third eyepiece, you can take photos and videos, as well as display the image in real time on the computer screen. At the same time, you can look through the microscope in the usual way. Devices with trinoculars are very functional and versatile, but they are complex and expensive.

— LCD screen. The microscope has an LCD screen that replaces the traditional eyepiece. You do not need to bend over to such a device each time to view the image, which is very convenient if observations need to be combined with record keeping and other similar activities. Microscopes of this design usually have a photo and video function, as well as various built-in tools — for example, a scale grid for estimating the size of visible objects, displayed directly on the screen. In addition, the image on the screen can be seen not only by the direct user, but also by everyone who is nearby; such features are indispensable during training sessions, consultations, presentations, etc. On the other hand, such microscopes turn out to be bulky and expensive.

— magnification factor. The magnification provided by the eyepiece. This parameter, along with the lens magnification, affects the overall magnification of the device (see above). The classic option for eyepieces in microscopes is 10x, but higher values \u200b\u200bare also found. The package may include several eyepieces, of different magnification — to change the overall degree of magnification. There is a multiplicity designation with a letter index, for example, WF10x. This means that the eyepiece has an extended field of view (WF — wide, EWF — extra wide, UWF — extra wide).

— Eyepiece tilt. The tilt of the eyepiece determines the position of the observer's head when looking through the microscope and the overall usability. According to this indicator, three main options can be distinguished: fixed angle, adjustable angle, without tilt. The fixed angle is most often 30° or 45° relative to the horizontal, these values are considered the most convenient. In angle-adjustable microscopes, the entire stand, with tube and stage, is fixed to the base with a swivel mount. This is the most convenient option, allowing you to adjust the tilt to your preference, but the mount tends to become loose over time, so it is rarely used in professional microscopes. The third variety — vertical microscopes, without tilt — have not received much distribution: this design is used in some stereoscopic models (see "Type") in order to ensure that the stage remains strictly horizontal (this is important for some work with microscopic objects).

— Rim diameter. The nominal diameter of the eyepiece used in the microscope, as well as the diameter of the hole in the tube, designed to install the eyepiece. Several standard diameters are used in modern microscopes, in particular 23 and 27 mm. In fact, this parameter is necessary, first of all, if you plan to purchase spare or replacement eyepieces for the microscope, or if you already have an eyepiece on the farm, and you need to evaluate its compatibility with this model.

— Diopter adjustment. The range of diopter correction provided in the eyepiece. This correction is used so that a nearsighted or farsighted person can look through the microscope without glasses or contact lenses. In most models with this function, the correction range is about 5 diopters in both directions; this allows the microscope to be used for low to moderate myopia/farsightedness.

The presence in the microscope of illumination directed from top to bottom. In biological microscopes (see "Type"), such illumination makes it possible to examine opaque objects; also in some cases it can be used as an addition to the main lower lighting. And in stereoscopic models, only overhead light is used — this is due to the specifics of the application.

Bottom lighting is a lighting system, the light from which is directed from the bottom up.

In conventional (not inverted) microscopes, such illumination is directed towards the objective through a hole in the stage. It is this type of illumination that is used for classical bright-field microscopy using through illumination; Thus, the lower arrangement of the illumination is traditional for biological microscopes and is provided for in most of these models. But the presence of this function in "stereoscopes" is not typical, although it also occurs.

In turn, in inverted microscopes, the upper and lower illuminations are actually “swapped”. Accordingly, in such models, this function is intended for examining preparations (mostly opaque) in reflected light, and the light flux is directed from the lens to the preparation.