Comparison Opto-Edu A11.1545-E vs BRESSER Duolux 20x-1280x

— 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 head 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).

— 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 greatest working distance provided by the microscope.

The working distance is the distance from the lens to the object in question. This parameter is important primarily for stereomicroscopes (see "Type"): the more space remains under the lens, the more convenient it is to work with various tools and devices in the field of view of the device. However, here it should be taken into account that the maximum working distance is achieved at the minimum magnification factor, as the magnification increases, the lens has to be brought closer to the object in question. For biological microscopes, the working distance does not really matter: such devices work mainly with flat preparations, to which the lens can be brought almost close.

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.

Camera sensor resolution in megapixels (millions of pixels).

The higher the resolution of the matrix, the higher the video resolution can be (see below), the more detailed the image is capable of providing the camera. At the same time, note that as the number of megapixels increases (without changing the size of the matrix), the size of each individual pixel decreases, which increases the likelihood of noise and deterioration of the overall image quality. Therefore, in itself, high resolution is not necessarily a sign of high quality — a lot depends on other points, for example, on the size of the matrix.

— 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).

Ways to transfer data to other devices provided in the design of the microscope.

This parameter is relevant primarily for digital and opto-digital models, as well as for individual optical devices equipped with cameras. All described microscopes can be equipped with AV and HDMI outputs, universal USB ports, removable media card readers, and Wi-Fi wireless modules. Here is a detailed description of each interface:

— AV output. Analogue output for video signal transmission. It is used primarily for live transmission of images from a microscope camera, and in some models — also for viewing footage stored in memory. Such outputs do not support HD resolutions and, in general, are inferior to HDMI in terms of overall “picture” quality (with the same camera characteristics). On the other hand, specifically for microscopes, these moments are not so often critical; analogue connectors are still quite popular in both conventional video equipment and special equipment; and the implementation of this interface is inexpensive. Therefore, AV outputs can be found even in fairly advanced models.

— HDMI. Digital output for video signal transmission. Similarly, AV can be used both for real-time broadcasting and for using the microscope as a video player when viewing saved materials (if such...a possibility is provided for in this model at all). At the same time, such outputs are more advanced than analogue AV: HD-quality images (including Full HD and higher) can be transmitted via HDMI, and the signal is very resistant to interference. We also recall that this interface is extremely common in modern video technology — in particular, the presence of at least one HDMI input is almost mandatory for TVs and monitors that support HD standards. On the other hand, the implementation of HDMI is noticeably more expensive, and it makes sense to use it with fairly advanced cameras, which in themselves significantly affect the price of microscopes. Therefore, such outputs can be found mainly in rather expensive and advanced devices.

— USB. Universal connector that allows different applications; a specific set of these options is directly related to the functionality of the microscope. Typical examples of using USB include the following: copying captured photos and videos to a computer or laptop; live image broadcast; remote control via PC / laptop (for example, moving the parent drug); charging the built-in battery, etc. The specific type of USB connector in the microscope may vary, however, usually, an appropriate cable is supplied in the kit for connecting to a standard full-size port.

— Card reader. The device for working with memory cards is usually SD, and in miniature pocket models — microSD. Such cards usually contain materials captured by the camera. In general, this function makes it much easier to copy information to other devices that also have card readers — primarily laptops and PCs; and miniature microSD cards are also supported by smartphones, tablets and other portable gadgets. Anyway, removing the card from the microscope and installing it in another device is often easier and faster than fiddling with a wired or Wi-Fi connection.

— Wi-Fi. A wireless module, which in this case is mainly used to communicate with an external device — such as a smartphone, laptop or PC. A Wi-Fi connection allows you to at least broadcast the image from the camera and copy the photos taken by it, and often also control other functions and settings (light brightness, movement of the driver, etc.). At the same time, the absence of wires provides additional freedom of movement and overall convenience. However, note that the specific communication format may be different, it should be specified separately. So, some models support only direct connection over a relatively short distance (in fact, up to a couple of tens of metres, or even less). Others are able to connect to an external device via the Internet, and here the distance does not play a role — there would be access to the World Wide Web. Still others allow both formats of work. Also note that individual devices with this function do not have their own screens at all and are designed for use with external gadgets; This design makes the microscope as compact and easy to carry as possible.