Comparison Micromed Evrika 40x-1280x vs Levenhuk Rainbow 50L Plus

— Optical. Traditional microscopes, which work based on the use of lenses and other optical elements. They allow you to provide high image quality and a good magnification factor, while they do not depend on electricity (except that batteries may be needed for the backlight system). This type of microscope uses traditional eyepieces, but there are some models that allow you to connect an external camera and display the image on a computer display. Also note that this is the only principle used in stereoscopic models (see "Type")

— Digital. Microscopes of this type are actually digital cameras, supplemented with powerful magnifying optics. The image from such a camera must be displayed on the screen; some models have their own displays, others do not have displays and need to be connected to a computer/laptop. The advantage of the first variety is independence from external equipment, the advantages of the second option are compactness and relatively low cost. At the same time, it should be noted that in terms of magnification, most digital microscopes are inferior to optical ones, and this principle is not suitable for a stereoscopic image.

— Optical-digital. Microscopes that combine the features of optical and digital models (see relevant paragraphs). Such models differ from "purely digital" devices by more advanced optics, with a revolving h...ead and a high magnification; from optical ones — with a built-in camera and using a screen as an eyepiece (traditional eyepieces are not used in optical-digital models).

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 correc...ted. 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 i...n the socket 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 design of the object stage provided in the microscope.

— Stationary. Subject table, fixed motionless; focus in such microscopes is carried out by moving up and down the tube with the objective and the eyepiece. Such systems are simple and inexpensive, but focus while looking through a constantly moving eyepiece is not very convenient. In addition, for advanced biological microscopes (see "Type") with binoculars and trinoculars (see "Eyepiece"), this option is also poorly suited for some design reasons. But the vast majority of stereomicroscopes are equipped with stationary tables — this is the most reasonable design, taking into account the specifics of the application.

— Movable. In microscopes of this type, the entire optical system is fixedly fixed on a tripod, and the stage can be moved up and down to focus the optics. This design is found exclusively in biological microscopes (see "Type"). It is somewhat more complicated and expensive than with a fixed table, but at the same time it is much more convenient: when focus, the eyepiece does not move, which allows you to comfortably adjust the image without looking up. In addition, it is the movable stage that is most suitable for advanced devices with binoculars and trinoculars (see "Eyepiece"), almost all such microscopes have such equipment.

Features of the design of the condenser installed in the microscope.

The condenser is part of the illumination system in biological microscopes (see "Type"). This is an optical system that processes the light flux entering the preparation glass in a special way. Different situations may require different ways of doing this; accordingly, different types of condensers can be used in microscopes. However, the most popular nowadays is the simplest Abbe condenser. It ensures the concentration of the beam of light and its uniform distribution over the field of view. Initially, such a device was intended for studies using the bright field method, but it can also be used for phase-contrast observations. The Abbe condenser can be equipped with an iris aperture diaphragm — with its help you can reduce the brightness of the illumination — as well as colour filters.

Other, more specific types of condensers (for example, phase or dark field) are usually purchased separately and are rarely included in the standard microscope equipment.

The characteristics of the condenser may indicate NA — the size of the aperture (active hole) in millimetres, for example, NA \u003d 1.2. This is a rather specific setting; suffice it to say that it is selected by the manufacturer for complete lenses and does not fundamentally affect the choice of a microscope.

The presence of light filters in the scope of delivery of the microscope.

Light filters are installed in the lighting system; they can be interchangeable or built-in (usually on a turret). Anyway, such devices change the characteristics of light, adjusting it to the specifics of the situation. The types and purpose of light filters can be different, as well as their range in the kit; here are some of the most common options:

— Blue colour. Useful in cases where light from an incandescent or "halogen" lamp is used for illumination. Such a filter equalizes the colour temperature (white balance), making the shades of colours colder and providing natural colour reproduction; this is especially important for microphotography, since a properly set white balance is critical to obtaining high-quality images.

— Yellow colour. Kind of the opposite of blue: lowers the colour temperature, giving the image a warmer tint. It is also sometimes useful for adjusting white balance, but yellow filters have another important use: they are well suited for detecting imperfections in metallic surfaces.

— Green colour. Achromatic and planachromatic objectives, which are installed in most modern microscopes, are best at eliminating aberrations in the green part of the spectrum. With this in mind, similar filters are applied: an image painted in a green tint has the least visible distortion. In addition, most objectiv...es for phase contrast microscopy are also most effective in the green part of the spectrum (although exceptions are possible).

— Matte (diffuser). White colour filters that do not change the colour of the light, but provide additional dispersion. This can be useful, in particular, when working with low magnification lenses.

— Neutral. Filters in different shades of grey. Used to reduce the intensity of lighting without changing its other characteristics. Such devices can be especially useful when taking photographs — namely, if the camera does not have a sufficiently fast shutter speed. Note that a similar effect can be achieved using a microscope diaphragm, but this is not always the best option when shooting. So, narrowing the aperture reduces the field of view and increases the depth of field (the latter is also not always desirable), while filters do not affect these parameters; besides, in some situations, even the narrowest aperture may not be “dark” enough.

— Light filters for coloured preparations. Improve the visibility of elements painted in a particular colour. Such fixtures are especially popular in biological studies, as they are the most commonly stained specimens and are also the most susceptible to dye fading, making it difficult to view under normal lighting conditions. Note that filters of this type, in contrast to the colour filters described above, do not colour the entire image in a certain colour, but only muffle all other colours, except for their “native”.

— Fluorescent. Filters used in fluorescence microscopy. They are divided into two types — exciting (they separate UV radiation from the general backlight spectrum to illuminate the drug) and closing (protect the user's eyes from ultraviolet radiation and at the same time let the fluorescent glow of the drug pass through).

— Adjustment of interpupillary distance. The ability to change the distance between the eyepieces in a binocular or trinocular microscope (see "Eyepiece"). For normal visibility, it is necessary that the distance between the lenses of the eyepieces correspond to the distance between the pupils of the user. This distance varies from person to person, so this setting may be required for comfortable use.

— Brightness adjustment. The ability to change the brightness of the backlight — to adjust the lighting to the specifics of the situation. For example, to study a thin transparent preparation in a bright field, high brightness will be unnecessary, but when transilluminating a dense dark object, it is indispensable.

— Illumination according to Keller. The presence of illumination in the microscope according to the Keller system. Such lighting is used exclusively in biological models (see "Type"), it is a sign of a professional level device. The Keller system complicates and increases the cost of the design, in addition, it may require specific settings, but with the right settings, the quality of the lighting is very high, and the image is as reliable as possible. Note that in microscopes there is a so-called. "simplified Keller system", when the settings are set at the factory and cannot be changed; however, in this case, it is precisely the full...-fledged, adjustable Keller lighting that is meant.

— Photo / video recording. Possibility of photo and video filming of the image visible in a microscope. Features of the implementation of this function in different microscopes may be different. For example, some models need to be connected to a computer, while others can record materials directly to a memory card or other media. Also, the cameras themselves, carrying out the shooting, can be both built-in and removable (see "Packaging" / relevant paragraphs).

Additional equipment supplied with the microscope.

— Camera. In this case, we mean a removable camera installed either on the main optical channel (to use an external screen as an eyepiece), or on the third additional channel of the trinocular (see "Eyepiece"). In addition, there are also built-in cameras (see the relevant paragraph). Some models supplied without a camera allow you to purchase it separately, but this configuration option is generally more convenient.

— Adapter for smartphone. A device that allows you to install a smartphone on a microscope so that the camera of the device “sees” the image in the eyepiece. Thus, you can take photos and videos on your smartphone, as well as use its screen as an eyepiece — for example, if you want to show the image to several people at once.

— A set of accessories and preparations. A set of accessories for working with a microscope. Such a set usually includes at least slides and coverslips; in addition to them, the kit can be supplied with preparation tools, various auxiliary compounds (resin for gluing, oils and liquids for immersion lenses), as well as ready-made preparations for testing the capabilities of the microscope and initial training in working with it.

— Lens Barlow. An additional lens that is installed in front of the eyepiece and changes the overall magnification — usually upwards, but vice ver...sa is also possible. To calculate the overall magnification when using such optics, you need to multiply the initial magnification of the device by the magnification of the lens: for example, a 200x microscope with a 1.6x Barlow lens will give 200 * 1.6 = 320x magnification. This is partly why Barlow lenses have a very low magnification — even it gives a significant increase in magnification. The second reason is that it makes sense to increase the overall magnification only up to a certain limit — above this limit, the optics will only stretch the image without increasing the detail. Actually, in many microscopes, this is exactly what happens if you set the device to the maximum magnification and install a Barlow lens. So this device should be considered more as a tool for adjusting the magnification at medium magnification, and not as a way to increase the maximum magnification.

— Cover / case. Case for storage and transportation of the microscope. Covers are called soft cases, they are mainly designed to protect against pollution; cases are made of hard materials, they are more bulky, but they are also able to protect the device from shocks and shocks.