What does a polarizing filter do. Polarizing filters. Principle of operation and recommendations for use

Every photographer strives to make their pictures unique. A lot of people resort to the help of various graphic editors. But there are tools that allow you to create unusual effects that are almost impossible to achieve with Photoshop. One such device is a polarizing filter.

How the filter works and effects

A polarizing filter (or simply "polarizer") converts and blocks polarized light. To achieve this effect allows a special polaroid film installed between the filter glasses. The outer glass rotates freely, while the inner glass is rigidly attached to the lens.

The photographs taken with the use of a light filter do not have glare, which may appear when shooting wet surfaces, glass. For example, a polarizer will help make the water deep and clear. You can take pictures of the bottom in the smallest details. It is important to note here that the polarizer is only able to remove reflections in one position. In certain planes, he will either weaken them a little, or not touch them. It is also impossible to remove glare from metal objects.

A polarizing filter is indispensable when photographing landscapes. If you choose the right shooting direction, a stunning effect of increasing saturation and contrast is achieved. The sky becomes dark blue, the clouds become brighter and more expressive. By rotating the outer part of the filter, the photographer can give richness to colors, achieve a change in shades.

Using polarizing filters

Typically, a filter is used when shooting on a sunny day. The maximum polarization of light can only be achieved in one direction. The camera lens should be at an angle of approximately ninety degrees to the flow of sunlight. Reducing the amount and brightness of glare and enhancing color saturation is achieved by rotating the polarizer ring. The filter will have no effect if the sun is in front of or behind the photographer. In this case, the light entering the lens is not polarized. Polaroid does not filter it.

The filter also works on a damp cloudy day. When the air is heavily saturated with moisture, you can take a picture with bright greenery.

It should be noted that the lens aperture is reduced. When using such accessories, it is easy to get an underexposed frame. Therefore, it is very important to check the correct exposure setting before taking a picture using the histogram.

Types of polarizing filters

Filters are linear and circular (circular).

1. Line Filters (PL) affect exposure accuracy. In cameras equipped with autofocus, this type of filter is not used, as it distorts the metering readings.

2. Circular filters (CPL) are marked CIRCULAR or C. This type of filter is traditionally used in digital photography and does not create any problems when working with autofocus. CPL filters are much more expensive than linear ones.

An important aspect when choosing a filter is its diameter, which must exactly match the diameter of your lens.

After a long sabbatical, I return to writing articles about photography. This time I will talk about such an accessory as polarizing filter. Back in 2005, I wrote a similar article, and now you can dig into it, but there is not much point in doing this. I wanted to update it, but after reading it, I realized that it was easier to write a new one.

What is a polarizing filter?

The essence of the filter is the polarization of light. I will not describe in detail what it is, you can read about the physical meaning of this phenomenon, for example, on Wikipedia or some other specialized site dedicated to physical phenomena. To be honest, I tried to understand what was written there, but I could not - everything that I was taught at the Polytechnic University in higher mathematics and physics 15 years ago was hopelessly forgotten. I'm sure the same thing happened to 99% of readers, so I'll tell you in simple words What is a polarizing filter?

Polarizing filter removes reflected light in photographs - sun glare, reflections from surfaces, sky glow due to reflection of sunlight from ice crystals in the atmosphere. As a result, shiny objects look like matte, and the sky in clear weather is not blue, but dark blue.

The polarizing filter can be rotated around its axis, which will change the nature of the polarization effect. Check out the example below and compare what the sky looks like and what the water looks like in these shots.

There is a reflection of the sky

There is no reflection of the sky, the bottom is visible. The blueness of the sky became a little dimmer.

Another example of a raw photo in Photoshop with an evening sky (by default, the camera was set to high color saturation for the landscape).

A little unnatural, but beautiful!

If you don't have a polarizing filter yet, maybe now you are starting to have an idea - you have to take it! I do not argue that a polarizing filter is a necessary thing for landscape photography. But he has a number of features that you need to know about in order not to be disappointed in the purchase.

Buy a circular polarizer

Polarization is linear and circular, respectively, polarizing filters are also divided into two groups - linear and circular. It is impossible to distinguish them in appearance - both of them have a rotating part, the external difference is only in the marking. Circular polarizers have the words CIRCULAR, CIR or simply group C in the marking (for example, CIR-PL or C-PL). If there is no such designation, then the polarizer is linear. It will shade the sky in the same way and remove glare from the water, but with it at the SLR autofocus will not work properly- phase focus sensors will fail. With a circular polarizer, there will be no such problems.

Buy an anti-reflective polarizer

The antireflection coating eliminates the effect of light reflection from the lenses in the optical system. If there is no antireflection layer, then a noticeable clouding of the picture is possible if the sun hits the lens. Also, uncoated optics have poor glare resistance. If you get hold of a lens with a red or gold ring ("top" Canon and Nikon optics, respectively), you should not hang a Chinese polarizer for 600 rubles on it. The lower price bar, from which more or less suitable polarizing filters begin, now lies in the region of 3000 rubles.

What is the best manufacturer of polarizers?

Each manufacturer of optics has its own division into classes, so this question is incorrect. In principle, you can take a filter from any manufacturer if the average price for it is higher than the indicated bar. A lot depends on the size of the filter. The larger the diameter, the more expensive the filter. I do not have comprehensive information on which filter to choose for N rubles, and I do not want to give recommendations "from the ceiling". I use the HOYA CIR-PL HD 77mm polarizer, it suits me completely. Do you want a proven by me personally solution, take HOYA CIR-PL HD.

For a wide-angle lens, buy a thin bezel filter

Still such filters are called "slim". They are slightly more expensive, but their frame will not be in the frame at the wide angle of the lens. If you shoot with a wide-angle and a filter with a standard "wide" frame screwed on it, it will turn out something like this:

On "full-frame" 24mm, the wide-border filter produces noticeable vignetting (darkening of the corners)

If you have an APS-C sensor (1.5 or 1.6 crop) and a 15-16mm wide-angle lens, then you will have the same. There is no noticeable vignetting from a wide frame at 18 millimeters.

Polarizer is not always useful

If we shoot in such a way that the sun is behind us or, conversely, shining in our face, there will be practically no visible effect from the polarizing filter.

The polarizer only works when we are facing the sun sideways. But because of this, the brightness "skew" of the sky regularly occurs - on the one hand it will be noticeably darker than on the other.

The sky on the right is much darker than on the left.

It also turns out funny when there is a "polarization hole" in the center of the frame, and natural vignetting of the lens (shaded corners of the picture) along the edges.

There are two bright "humps" in the sky

All these things spoil photos rather than make them expressive, so try to get rid of vignetting by stopping the aperture down to 8. Vignetting is also easily corrected in Lightroom if it "knows" your lens profile (if it doesn't - ).

Regarding the "polarization hole in the sky", see the following recommendation...

Don't abuse the ultra-wide angle!

At 24mm, the brightness skew of the sky will be quite noticeable (see the previous photo), not to mention the smaller focal lengths. But if you move the zoom up to about 35-40mm (full-frame equivalent), then the sky will be more "smooth".

Here everything is more or less normal! The lens in the middle zoom position does not vignette, the polarizer does not "gnaw out" a hole in the sky

Polarizer can be combined with gradient filter

A gradient filter is a piece of glass divided into two halves - transparent and darkened. You can read more about it. Then you can get almost fantastic pictures without any Photoshop...

Remember that two filters increase vignetting at wide angle. Increase the focal length to keep the filter frame out of the frame.

And yet - do not twist the filters tightly with each other! Due to the notches on the edge of the ring, the filters easily cling to each other and it will cost a lot of work to unscrew them later (considering that both have moving parts that will scroll when you try to unscrew the structure you have assembled).

Polarizer can be combined with other polarizer

This will simulate a gray variable density filter - in theory, a handy thing for shooting during the day with ultra-long shutter speeds. By rotating the filters relative to each other, almost zero light transmission can be achieved. However, side effects are also possible - a decrease in glare resistance, color distortion. Not to mention that autofocus will never break through such "armor" and you will have to focus before putting the filter on the lens.

The setting sun, when shooting through two polarizers, unexpectedly turned blue for everyone and gave huge red highlights

This example was made and given for reasons of "what if" ... To be honest, I have a hard time imagining the practical value of this solution, but perhaps someone will develop this idea into something interesting :)

A shady sky effect can easily be done in Lightroom without any polarizer!

Open the photo and the section "Correction"

We do the following things:

1. Open the photo and select the tab "Correction"

2. Scroll down the tools to the section "HSL / Color / Grayscale"

3. Select the "Lightness" setting (1)

4. Click with the mouse on the inconspicuous circle (2). The mouse cursor changes shape from an arrow to a crosshair and a circle with arrows just below.

5. Move the cursor to the sky, where it is without clouds (3), cling to it with the mouse and drag it down. In this case, the sky will darken as if the photo was taken with a polarizer.

You can try other tools in the HSL/Color/Grayscale section, such as Hue. To cancel an action, use the key combination Ctrl+Z.

This is where I will end. Regarding whether you need a polarizer, I will answer with a phrase from a famous song - "think for yourself, decide for yourself - to have or not to have" :)

Quite often we hear the myth that the era of filters has passed. The almighty Photoshop allows you to change the image as you like during post-processing. Alas and alas! This is not so... The post-editor not only does not protect the lens of your camera, but is also practically powerless in front of the overexposed sky, which will only have to be redrawn if you did not apply the gradient filter in time. Let's take a look at what filters serve for what, and how they can make life easier for a photographer, reducing the percentage of technical marriage to almost nothing.

Light filters are special attachments on the camera lens that allow you to achieve a certain effect (cut off the excess, give the image the desired shade, soften the light, and so on).

They make it possible to achieve the desired effect on their own, without limiting creativity to software capabilities - no matter how wide they are, the photographer’s view, his taste and imagination cannot be replaced by them. The skill of working with corrective nozzles is useful for anyone who wants to achieve truly artistic, original shots. At the same time, one must be aware of the possible difficulties.

Filters are used strictly when necessary, because any additional object between the lens and the subject can reduce the quality of the final result. Incorrect or excessive use of an enhancement reduces contrast (local or overall), causes unnecessary glare or physical vignetting, when the image becomes dark at the edges, and can change the color ratio for the worse. The photographer needs to clearly understand what result he needs to get and use spot filters.

The main types of filters

Even structurally, the filters differ from each other. Some are installed directly into the thread, others through a special holder - a compendium. But in fact, it is a small glass with a certain coating, which is installed in front of the lens. In this article, we will consider the difference in the purpose and optical properties of the models.

Depending on the attachment, filters are:

• - the size is selected according to the diameter of the lens, but, in principle, if the parameters do not match, you can use the adapter ring;
• - more flexible in operation, used with almost all models of lenses, but they have to be held by hand.

If we start from the destination, then all filters can be separated on the:

• protective - they do not let dust, dirt, the flow of UV radiation invisible to the eye, protect the lens from mechanical damage;
• polarizing - reduce the amount of reflected light, the most important filters in landscape and landscape photography;
• neutral (ND), blurring and gradient, with a transition in sharpness;
• with a specific effect - corrective and softening, macro, contrasting, enhancing individual colors, infrared, giving the "star effect" and so on.

by Pak Chu. infrared filter. NIKON D70s, Nikkor 18-105mm, 18mm, ƒ/11/1/80s/ISO 200

Protective filters - lens safety and color balance normalization

Protective filters, despite the name, not only protect the front lens of the lenses from scratches, dust and other troubles. This function is exclusively performed by clear-models made of transparent, clarified glass, which are inexpensive and widespread. They are usually screwed to the lens and allow you to worry less about the safety of the front lens in the field.

Protective filters not only protect against mechanical damage, but also combine UV protection. Of artistic interest are two other types of protective light filters: UV and Skylight. The first type, UV filters that provide ultraviolet protection, are often the subject of heated debate. On the one hand, their use increases contrast and reduces haze, on the other hand, modern digital cameras successfully cope with the task on their own. However, UV filters are needed to protect the lens from damage (they are almost transparent) and at the same time "optimize" the image by slightly sharpening without changing the color ratio. It is worth choosing only models with a multi-layer coating to avoid unwanted glare.

Skylight models (light pink) normalize color balance by absorbing excess spectrum in the blue zone. They make the color of the daytime sky a little warmer due to the correction. Such filters are used to give the image a so-called mood, to deepen it a little, to make it more contrast - literally with a few barely noticeable “brush strokes”. Skylight filters are sometimes used in portrait photography (softening the frame) or on an overcast day (sharpening).

Landscape photography with polarizing filters

One of the most expensive, but, nevertheless, popular and often bought light filters are polarizers. They significantly reduce the amount of reflected light that hits the camera, which helps to reduce glare from water or the sun and the contrast between sky and landscape. Their action can be compared with protective polarized glasses. Filters are labeled PL (Polarizing Filter) or C-PL (Circular Polarizing Filter) and can usually be adjusted for the intensity of the effect. The main advantage of polarizers is the addition of color, especially on a bright sunny day, when the rays literally burn out the color saturation of the frame.

This cannot be achieved using post-processing, so such filters cannot be replaced by a graphics editor.

Polarizing filters are divided into:

• linear - a budget option that is not used with TTL cameras;
• circular, allowing for autofocus and metering, while the camera works optimally.

A polarizing filter will make the color of the sky deep and blue, add brightness to greenery and water, and increase contrast. You need to be careful with it: the filter reduces the amount of light entering the lens, and in low light, the risk of blurring and blurring the frame increases. Another mistake, mostly by novice photographers, when they overdo it with intensity, and the sky takes on an unnatural color - violet or ultramarine. But, if the goal is to achieve such an effect, you need to place the camera as perpendicular to the sun as possible (or better, if it is at its zenith at all). Then the polarization will be maximum.

You can also use a wide-angle lens - although usually excessive darkening of the sky is considered a photographic flaw.

ND filters - soft blur

Many photographers manage to achieve a beautiful effect at slow shutter speeds - softness, barely noticeable blurring of the boundaries of the object, foggy haze, smoothness of the water flow.

Recently, variable density ND filters have become common, when you can adjust the amount by which you need to reduce the amount of light. These filters are two polarizing filters, which reduce the amount of light from 1 to 8 steps (stops) due to rotation. But in turn, these filters have all the properties of polarizing filters, and therefore some of their shortcomings, for example, they change the color reproduction of the resulting image, which can have a rather positive effect, but can also cause dissatisfaction with the photographer.

Do not confuse neutral density filters with gradient filters (ND Grad, GND), which affect only part of the frame, darkening it. Models of neutral density (with a grayish tint) absorb the light fluxes passing through them without changing the color rendition. This allows you to increase exposure time and reduce diffraction.

ND filters are useful when shooting in mountains covered with snow; near water, especially flowing (rivers, waterfalls). These are true friends of landscape painters. With their help, you can get a smaller depth of field if the light is very bright, and also, for example, effectively blur a moving object - a car, a person (motion blur). But ND greatly reduces the illumination and sometimes changes the color balance a little. They show themselves best on a bright sunny day - they bring a sense of movement to the frame, allow you to flexibly choose the aperture.

Interesting effects can be achieved at dusk, at dawn - the surf or the clouds will be painted with a picturesque haze. gradient filters it is good to use in scenes with simple geometry - they gradually reduce the degree of illumination. The picture becomes dramatic: for example, a sharp transition from the sky to the relief, circular blackout.

Soft and special effects

There are filters focused on performing narrowly specific tasks. These include, in particular, models with a soft effect. These filters soften, “fog” the object, but at the same time the image remains quite high definition. With the help of such filters, you can smooth out imperfections in portraits, remove ugly details, and so on. There are several varieties of these filters - warm, silky, spot, duto - that give the skin a warm tone, reduce sharpness, and blur the edges of the frame. The artistic effect is caused by uncorrected spherical . With the help of such devices, you can make the image soft without losing clarity - for example, shooting wide open with duto filters.

Special warm and cold models that change the white balance have become less popular due to the fact that the software in digital cameras does a good job of this. On the other hand, they can add color to a cloudy day, creating a "sunset effect"; make the frame yellow, blue, green (so that post-processing is not needed); perform well underwater. Also, creative filters for a specific purpose include:

• ray ("stars", star) - point light sources (lanterns, windows) become like stars with divergent rays. The effect is caused by a microscopic grid applied to the filter. To get the right frame, you should experiment with the aperture and rotate the "asterisk" around the axis;
• infrared - transmit radiation from 700 nm. They allow you to take unusual photos - the blue sky will become almost black, and the greenery - white. At the same time, the clouds retain their usual shade, the contrast of the image increases.

Soft filters and stars can be easily replaced with filters in the post-editor, but if you prefer to see the future conceived picture right away, then there should be room for these filters in your backpack.

Lens filters are a wonderful creative tool in the hands of a photographer. Use these accessories wisely and to your heart's content!

It is one of the most important filters in the landscape photographer's arsenal: it cuts out excess polarized light, increasing the color saturation of the scene and suppressing unwanted reflections, and its effect cannot be reproduced in digital processing of photos.

In order not to delve into the jungle of the physics of light, to begin with, let's take it on faith that light is polarized by reflecting from non-metallic surfaces. The most obvious examples of such reflected light are glare and reflections on the surface of water and glass. A circular polarizing filter (we will not talk about linear ones, they are used quite rarely in photography) allows you to filter out direct reflections of sunlight at certain angles. The filtering angle is controlled by the rotation of its front element (the rear element is screwed onto the thread for filters on the lens), and the strength of the effect is controlled by the position of the camera relative to the sun.

Thus, the polarizing filter suppresses glare and reflections, allowing you to naturally increase the saturation of the colors in the picture. To the greatest extent, this effect is manifested in the sky - it becomes more saturated, and clouds are much better visible on it.

To see in which direction to shoot for maximum effect, you can apply the “rule of thumb”: point your index finger at the sun, sticking out your thumb; for maximum effect, you need to shoot in any direction in which the thumb points, if you rotate the brush around the axis formed by the index finger. Ultimately, it turns out that the polarizing filter becomes most effective when the sun is on the side of the camera.

There are several benefits to using polarizing filters, but they come at a cost.

• The saturation of colors increases as a result of the reduction in the number of direct reflections of light. This effect is the first thing that catches your eye. Saturation, however, does not always increase evenly throughout the image. The amount of the effect depends on the position of the subject relative to the sun, as well as its reflectivity - the higher it is, the more the color saturation will increase. In addition, the effect of the polarizing filter is more noticeable on a clear sunny day than on a cloudy one. There may also be problems with the uniformity of the effect when used with ultra wide-angle lenses with a focal length of less than 28 mm and when shooting panoramas;
• A polarizing filter is an indispensable tool for suppressing reflections. It allows you to much more clearly outline wet objects or those that are under water. This ability also makes it useful when shooting objects behind glass - in storefronts, behind windows, etc.

• It simplifies shooting scenes with a wide dynamic range, allowing you to more or less balance, for example, bright skies and dark foliage;
• When used on long lenses in particular, it is a good option for combating haze and increasing image contrast. However, if the subject itself is highly reflective, its contrast is very likely to decrease.
• A high quality filter will take your landscape photography to the next level and really add depth to your shots. On the other hand, cheap low-quality filters are likely to further reduce the contrast and sharpness of the image and catch sun glare. Also, with wide-angle lenses, you will most likely need to use thin-rimmed polarizing filters to avoid vignetting;

• The polarizing filter cuts off unnecessary reflections, which means a loss in light, and quite a significant one - a little over two stops on average. This makes polarizing filters useless when shooting in low light conditions, working at sports events. At the same time, a polarizing filter is a good replacement for a low-density ND filter, if circumstances so require. In addition, they can be used in combination with ND filters if required.
• There is now a wide range of circular polarizing filters on the market in various qualities, available at a very wide price range - prices vary depending on lens thread diameter and manufacturer. There are decent quality solutions at an affordable price, for example.

Obviously, a circular polarizing filter is a win-win if you want to improve the quality of your landscapes. However, this is one of the most expensive types of filters you will find on the market, and for good reason. This is one of those "glasses" that obeys the principle of choosing a lens - it is better to invest in a good product from the very beginning and enjoy using it for years, if not decades, with proper care. There is, however, a savings option: one large diameter filter with a set of adapter rings will be enough to use with all your lenses - there is no special need to spend money on a filter for each lens.

It mentioned polarizing filters, but I did not describe them, promising to return to them later.

It's summer, which means it's time to talk about these interesting devices.
Despite the fact that there is a lot of information about polarizing filters, when I look around at people taking pictures, I rarely notice how a polarizing filter is used.

Meanwhile, the competent use of a polarizing filter in many cases will improve photographs, add raisins to them.

Pictures for commercial use are often, if not most, taken by professionals through polarizing filters.

A bit of theory.

You don't need to understand the theory. For example, I know her very superficially. If you just need a result, then you can skip the theory and replace it with practice, guided by a few tips that I give below.

But still, a little theory.

Polarization of light is the separation of rays from natural light with a certain orientation of the wave oscillation plane.

The light of the sun has no polarization, i.e. light waves oscillate in all planes at once. However, sunlight, being reflected from some surfaces, acquires polarization, i.e. the wave of reflected light oscillates in only one plane.
Reflected light is light glare on various smooth surfaces, reflection on water, on glass, etc.

The scattered light of the sky and air haze are also, in many respects, a consequence of the multiple reflection of the sun's rays from water or other dust in the air.

So, sunlight is not polarized, and its reflections are often polarized.

How does a polarizing filter work?

The human eye cannot distinguish between polarized and unpolarized light. Light and light.

The polarizing filter has a unique property - the ability to transmit light only polarized in one specific plane. The picture shows this effect.
Light passing through such a filter becomes polarized.

With the help of a polarizing filter, it is possible to pass light into the lens with fluctuations only in one or another specific plane.

In practice in photography, this ability of the filter is used just to cut off some waves, not to let them into the lens.

Reflections are polarized light, and therefore they can be cut off by turning the filter to a certain angle, which blocks exactly the plane in which the reflection light oscillates.

At the same time, sunlight will still pass through the filter, because. Again, sunlight is not polarized in any one plane.

Of course, not all sunlight will pass through the filter. That part of it, which oscillates in the same plane as the cut-off light, will also not overcome the filter.

Therefore, a polarizing filter always works simultaneously as a neutral filter, darkening the image by 2-3 steps.

Finished with theory.

In photography, a polarizing filter, in particular, allows you to:

1. Remove the whitish haze from the sky and show the sky in a rich dark blue color. At the same time, the clouds remain bright white, contrasting and expressive. Very beautiful.

2. Remove air haze from the landscape and show the landscape with brighter rich colors. Visually, the contrast increases and there is a feeling of increased sharpness and clarity.

3. Remove reflections from the surface of the water (window glass) and show what is under the water (behind the glass).

A polarizing filter is visually similar to a neutral density filter. It is screwed onto the front of the camera lens. But there is a difference.

The filter frame consists of 2 interlocking rings that can be rotated relative to each other around the optical axis.

After the filter is screwed to the lens, it is possible to arbitrarily rotate the filter glass itself around the optical axis. So, in fact, the filter is tuned to cut off a specific plane of oscillation of light waves.
The performance of a polarizing filter depends on two factors:
1) the correct orientation of the camera in relation to the surrounding reality;
2) the angle of rotation of the filter in the frame.

We look at the subject through the viewfinder from different directions and turn the filter frame. The effect of the filter on the picture is clearly visible visually. All the main patterns will immediately become clear.

There are a few things to keep in mind when using a polarizing filter:

1. There are two types of polarizing filters: Linear and circular (circular).

Linear ones appeared much earlier and for the purposes of the photo they are most likely not being produced anymore.

Polarizing filters were also produced in the USSR. For example, in the photo PF-49. PF, is, of course, the "Polarizing Filter", and the number 49 is the diameter of the thread. All Soviet polarizing filters are linear.

Linear filters are not very convenient to use with modern cameras. With t.z. eliminate glare, reflections, haze, etc. - the filter will work as it should. But in a modern device, most likely, metering and autofocus will lie.
The linear filter polarizes the light, and the device's sensors are sensitive to polarization.

The natural conclusion is that if you use manual lenses on a modern device and know how to enter exposure compensation into the device, you can safely use a linear filter, for example, a Soviet one on a digital SLR. Everything will turn out as it should.

On a Soviet lens, a Soviet polarizing filter would look quite appropriate.

The range of these filters is shown in the figure. For example, the most common lens of the Helios-44X-X series has a M52 × 0.75 filter thread.
Circular filters are more modern. They are released just to ensure that metering and autofocus work correctly on modern devices.

The circular filter has 2 layers. The first layer is an ordinary linear filter. It cuts off all but the selected waves and polarizes the light.

The second layer allows linear polarization to be turned into circular. Those. as if no longer polarized light reaches the automation of the apparatus.
In terms of the final effect on the image, circular filters do not differ from linear ones.

To be sure to distinguish a linear filter from a circular filter, there is a very clear and simple test that I found on the About Photo resource.

Even if there are no inscriptions on the filter, this is very easy to do. Approach the mirror, turn on the light, although it's better in reverse order, it's cheaper. Look through the filter like a monocle. The outer side of the eye, the inner side of the mirror. If the filter in the reflection is opaque, turned into a black circle, then it is a filter with circular polarization. If the filter in the reflection is transparent, then either you turned it the wrong way, or it is a linear filter.

Even if you know for sure that your filter is circular, try to do as it is written. It's mesmerizing.

If you buy a new filter, then its type can be understood by the marking.
Circular polarizers have the words CIRCULAR, CIR or simply the letter C in the marking (for example, CIR-PL or C-PL).
You can visually see the operation of the filter, any, both linear and circular, in a very simple way. The light from computer monitors is polarized. If you look through the filter at the monitor image and rotate the filter around the optical axis, you can choose an angle at which the monitor image is completely invisible. The filter appears to be opaque.

So you can roughly check the quality of the film in the filter (and in polarized sunglasses, by the way). A bad film will not give a uniform full blackout, but spots of light and dark areas.

Here I have some funny shots where the filter completely darkens the image from the monitor, but through it you can see different objects, or my hand.

2. If you are going to photograph blue skies, then consider the following:

When the sun is near the horizon (at sunrise and sunset), the most polarized areas of the blue sky are overhead (at the zenith) and perpendicular to the direction of the sun's rays. In this case, the optical axis of the lens should be located along the north-south line.

At noon, when the sun is at its zenith, the sky is polarized in all directions at an angle of 45° to the horizon. Sky polarization decreases upwards.

The most polarized are those parts of the sky that fall into the image field when the object is illuminated by side sunlight, i.e. when the direction of the sun's rays and the direction of shooting (the optical axis of the lens) form a right angle.

In this case, the filter darkens the sky to the greatest extent. The polarization of parts of the sky decreases as you get closer to the sun.

The areas of the sky lying in the directions to the sun, above and below the sun, and also in the opposite direction from the sun, are not polarized or almost not polarized. These areas are included in the image field when shooting against the sun (backlighting) or when the sun is behind the camera (front lighting).

In cloudy weather, a polarizing filter will not work with the sky in any way.

The left (the first of the pair) shots were taken without a filter, the right (the second of the pair) were taken with a filter. The unevenness of the color is made intentionally for an example ..

3. If you are going to shoot clear water:

To eliminate the reflection on the water, you need to turn the filter to a different angle than the one that darkens the sky. This means that it is impossible to achieve the effect of transparency of water and blue sky at the same time.

I do not consider the option of using several polarizing filters at a time as completely exotic.

There should not be large waves on the water, because. waves reflect light at different angles, which means that it will not be possible to eliminate all reflections at one filter position.

Personally, I like the effect of water transparency the most.

4. If you are using a wide angle lens:
The paragraph about the sky has recommendations for shooting directions depending on the position of the sun. When shooting water, there is also a similar dependence on the angle of the lens to the surface of the water to maximize the effect. Everything is less critical there, so I won’t dwell on it in detail.

And I say all this here because when you shoot with a wide-angle lens, a very large area of ​​\u200b\u200bspace gets into the frame.

And if the center of this area even 100% complies with the recommendations for the angle of the optical axis to the sun's rays when shooting the sky or at the corners to the surface of the water, the peripheral area will receive light from a completely different part of space.

And in this area the angles will not be optimal.

Therefore, your sky may darken unevenly. One side is stronger than the other. Or there will be a darker area of ​​the sky in the center of the frame.

In my photo of the houses you can see that the left side of the sky is darker than the right side. In order for the sky to be painted evenly, it was necessary to shift the frame to the left. But it's an ugly house. Here, choose.

Likewise with water. The reflection will disappear in the central area, and gradually appear towards the edges.

All this can be seen in the viewfinder and you just need to pay attention to this feature. In some cases, you can zoom in the direction of increasing the RF. In some - turn the filter a little and reduce the strength of the effect.

Well, or write this feature into the plot.

More about wide-angle lenses.

For a wide-angle lens, you need a filter with a narrow frame. Otherwise, the frame will enter the frame and cause vignetting.

This is kind of obvious, but the design of the filter involves two movable rings and making them completely thin is not very simple.

Suitable filters are labeled "slim" and cost a little more.

5. The polarizing filter works like a neutral filter with such a solid multiplicity.

On bright days, this provides a number of advantages, but if shooting in the shade, then it can be difficult.

The filter reduces the amount of light entering the lens by 2-3 stops. I previously shot with the wide-angle Tokina 17-35 f/4. The lens is not very fast, but quite affordable.

So, with such aperture, and with a polarizing filter on, the camera simply did not want to focus automatically in some situations of shaded scenes. Manual focus helped out, and wide-angle is loyal to focus misses, but still, keep in mind.

These filters are not expensive. Don't chase after the coolest and most expensive brand. The difference in the end result is imperceptible.

Don't bother with theory. Just try. Masterpieces are not guaranteed. Not always and not everything can be removed with the maximum and ideal effect. But interesting photos are guaranteed.

Happy pictures!

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