Fixed lens or zoom lens: which one is better to use? Zoom - what is it? Better sharpness and image quality

Zoom in a camera is a characteristic of the lens and depends on the focal length (FL). FR is expressed in millimeters and indicates the distance from the middle of the lens to the focusing point, that is, to the matrix. On the lens, the FR is indicated by a pair of numbers, for example, like this: 5.8-24 mm. At the short end the focal length is 5.8 mm, and at the long end it is 24 mm. And we get the zoom value by dividing these two numbers by each other.

The term zoom is used for lenses with variable focal lengths. In our example, a lens with a focal length of 5.8-24 mm and the zoom will be equal to 4. This value was obtained by dividing the long focus distance by the short one 24/5.8 = 4.

Practical use of zoom

When selling, they will tell you that the zoom indicates how many times the camera can magnify an object. According to theory, for the angle of view of the human eye, the optimal focal length is 50 mm and this value should be used instead of the FR value at the short end. If, for example, the FR is 35-105 mm, then the zoom will be 105/35=3. And the increase will be 105/50 = 2.1. Therefore, the camera zoom value does not mean exactly how much the object can be enlarged. Well, this is all complicated, and it is important for the buyer to know that the zoom indicator is not an important characteristic of the lens.

Optical zoom

Optical zoom is a characteristic of the camera's optical system. Approaching or moving away from the subject occurs by shifting the lenses in the lens, while all other characteristics of the camera remain unchanged. Therefore, the quality of the pictures will be high, and it is the optical zoom that is recommended to be used when shooting. And when asked how to choose a camera, you need to pay attention to the size of the optical zoom, not the digital one.

Digital zoom

And if digital zoom is also indicated on the camera, then many people have an ambiguous attitude towards it. After all, with digital zoom, the processor cuts out the required piece from the image and stretches it to the entire size of the matrix, and there is no real enlargement of the object. This can be done on a computer when enlarging the image. With such an increase, the resolution of the cut out area will decrease.

For a camera, optical zoom is of greater importance. When shooting, it is advisable to disable digital zoom in the camera settings.

Digital zoom should be used with caution. Its use is justified when the matrix comes with a large margin of resolution, and when there is simply no other choice and you need to take a photograph with a close-up object.

Superzooms and ultrazooms

Today, stores offer a large selection of cameras with large zooms. Such cameras are called superzooms or ultrazooms. The optical zoom value in such cameras reaches 50x and even 60x.

For example, consider a camera like the Canon PowerShot SX60 HS. It has an optical zoom value of 65x. In this case, the FR: f = 3.8 – 247 mm (21 – 1365 mm in 35 mm equivalent), and the aperture: f/3.4 – f/6.5. Construction: 15 elements in 11 groups. The cost of such a camera is approximately $750.

Canon PowerShot SX60HS

Or another representative of superzooms: the Nikon Coolpix P600 camera. The zoom value reaches 60x. FR: 4.3 – 258 mm (24 – 1440 mm in 35 mm format), aperture: f/3.3 - 6.5, design: 16 elements in 11 groups. The approximate price of Nikon Coolpix P600 is $430.

Nikon Coolpix P600

Additional information on zoom

It also happens that the price tag indicates the zoom value obtained by multiplying the digital and optical zoom values. This indicator does not need to be taken into account at all, but rather, check the value of the optical zoom or find out the focal length and lens aperture value and make a choice based on these parameters. After all, in all lenses, next to the DF, the aperture value for these distances is also indicated. And the greater the difference in the FR values ​​(the larger the zoom), the lower the lens aperture (the amount of light passing through it to the matrix), because the number of lenses in the lens increases. Therefore, in compact cameras, a zoom value greater than 4 can significantly reduce the aperture value and, accordingly, the quality of the photograph.

View of the 30x zoom lens

But another thing that makes zoom deceptive is that it has the same value for different focal lengths. For example, two cameras with an optical zoom of 3 have different focal lengths. One has a FR of 70-210 mm, and the other has 18-55 mm. One is used for shooting portraits, and the second for shooting landscapes. But the zoom is the same. Therefore, when choosing a camera based on its zoom, you may be missing out on other important features.

A larger zoom value does not always mean better photo quality, but rather the opposite. It is only useful for filming distant objects. There is no one answer to what you should choose, but when choosing a camera for yourself, you must understand what you are choosing and where you will use it. And then you will be able to answer yourself whether a large zoom is needed for your camera.

Roger Cicala, founder of Lens Rentals and one of the most entertaining and informative voices in the world of optical testing, believes that zooms are never as good as primes. And I’m ready to give strong arguments in favor of my research into technology. Let's give the floor to a specialist.

It's interesting to see how differently people approach situations when the scientific collides with the creative. The scientist states: “Facts are more important than feelings.” The Creator objects: “Only my vision and design matter.” This is exactly the case in fine art. Whether a photographer or videographer achieves the intended shot is the measure, and the equipment used is secondary, so I don't argue when an artist states that all the tests in the world can't influence his choice of equipment. I accept his words that “only this lens” is the best and ideal for him.

But, while not challenging the right of shooters to have their own opinion about what equipment is ideal for each individual, I continue to believe that misinformation and lack of knowledge are harmful. Therefore, I’m going to deal with a statement that is often and obsessively found on the Internet, infuriating my inner scientist: “This zoom is as good as the prime. (And the following from the first - give me the best copy of this zoom).”

We will use a scientific approach, which involves familiarity with my testing methods and interpretation of results. (Without a scientific approach, I would simply state that this lens scored 82.7 in our rating, the meaning of which you do not understand, and the other - 79.2, and the article would be short, which our editors like so much. By the way, the editors hate me ).

Let's start with MTF charts, which I know many people don't understand and refuse to learn to understand. This part will be mercifully short, and then we will move on to the long-awaited pictures. Just be patient, I’ll make it easier for you by using our experimental method of subliminal encouraging text: it works unnoticed, but the positive charge goes straight to the subconscious, instilling a lasting feeling of well-being and achievement of goals.

The science is on, but no math yet, so be patient. You can do it, I promise.

You've probably seen MTF charts. Even if you don't understand them, I think you have the idea that the higher the lines on the graph, the better. You've probably already evaluated lenses by comparing the placement of lines on graphs. MTF graphs show the average performance of real lenses (if the graphs were created by Zeiss, Leica or myself), or a computer model of the theoretical best possible scenario (for all other graphs). The graph shows how half of the lens performs - starting from the center (left side of the graph) to the edge of the image (right side).

Here are the MTF graphs of the two lenses, from which we can conclude that the resolution of the left one is higher than that of the right one. The graphs say a lot more, but we’ll limit ourselves to the main thing - the higher the line on the graph, the sharper the lens.

There is one "but": the graphs display either the average performance of many lenses, or ideal performance simulated by a computer. Now we take on testing. Firstly, you can see that our graph shows not half, but the entire field of the lens. The center of our image is in the center, and not on the left edge of the graph. Secondly, it is immediately clear that one side is clearly different from the other. With mass production, it is impossible to make everything perfect. By the way, this is a chart of the MTF model, the average chart of which was above on the left.

It can be seen that the left side is different from the right. But if one side is different from the other, how do the top and bottom of the frame relate? Or corner-to-corner? If we want to truly test a lens, we need to take readings multiple times, rotating the lens to get data from different areas of the frame. Here's a graph of our lens tested at four rotations.

We're almost done with the boring explanations. There is very little left. You can do it!

This is a graph plotted over four rotations. You could do it at 8 or twelve, but the pictures will be very small, and you’ll already be bored. You’re probably thinking: “Just say 79.2 out of 100 in a simple way instead of all this drudgery!”

What if, instead of lines, we graphically display how MTF is distributed over the surface of the frame? Below is a map of the sagittal MTF, where blue shows the area of ​​greatest sharpness, yellow - slightly worse, and red (in this case it is absent) - where sharpness is not very good.

Do you agree that this is much clearer? It's immediately clear that our test unit is well centered (highest MTF in the center) and the right side is slightly less sharp than the left. More details later, but if you test it yourself, you won't notice such a minor difference. The MTF test bench is much more sensitive than any camera (at least to date).

Maps of other lens metrics can be made. Below, for example, is a map of the astigmatism of the same lens.

MTF is over for today. Now you can look at cute color pictures, achieving peace and relaxation.

It can be seen that the lens in question has increased astigmatism on the right edge. Such cards are an easy and reliable way to evaluate a specific lens at a glance. There will be a whole bunch of these pictures later, so I tried to explain how we get them.

Will this be noticeable in real photographs?

I already said that our optical test bench is much more sensitive than a camera. It distinguishes very minor deviations, which in real photographs will be masked by other variables present in the frame - lighting, focusing, location of objects and many others. Serious deviations will be noticeable. How serious? Let's look at the cards of two copies of the same lens model, one of which meets all the requirements, the other is worse. (Actually, it's not bad at all, with the only worrying area being the red area at the bottom.) If you were shooting with this lens, you'd probably rate it "good" or "a little soft." If you shot it second, you would describe it as “outstanding.”

(The map appears cropped compared to the one shown above. This lens has a built-in limiter to reduce reflections, and the image it produces is a rectangle, similar to a camera sensor, rather than a circle, like the one above.)

I understand that it’s more pleasant to evaluate lenses based on colorful photographs, but a stage shot has too many variables, and we strive for science. You'll have to make do with photographs of test tables.

Let's compare the top part above the center of the frame, which was excellent on the right lens and good on the left. To fit 100% of the crop into the format of this unfortunate blog, you will have to place them on top of each other: the right lens on top, and the left one on the bottom. These are crops of RAW images of high-quality test patterns taken on a 36-megapixel camera, without sharpening. On a camera with a higher resolution the difference will be more obvious, with a lower resolution it will be less noticeable, but for our purposes these images will be suitable.

I can see the difference, and I think you can too. If I had shot in JPEG rather than RAW, the difference due to in-camera sharpening would have been less noticeable. Don't forget that test charts are easier to evaluate than photographs, and in real photographs the difference would only be noticeable in a side-by-side comparison. If you bought the lens, the map of which is shown on the left, you would hardly complain about blurriness at the top of the frame, especially after some post-processing and when posting JPEGs with a resolution of 800 pixels on the long side.

Let's look at the lower left area. As before, the right lens is on top and the left is on the bottom.

Here the difference is greater. It can be assumed that there is something wrong with this angle. Tangential test lines (those from top left to bottom right) appear gray on gray, indicating low detail. That's it, let's limit ourselves to this. I just wanted to show that our MTF maps reflect the real state of affairs.

Isn't it time to talk about zooms?

It's coming soon, my patient friends. We're done with the conceptual part, there's not much left to do.

Many people know that a zoom, even if comparable to a prime lens in terms of sharpness in the center of the frame, can rarely boast the same sharpness at the edges and corners of the frame.

But few people think about how much more complicated a zoom lens is than a prime lens. The optical design of a zoom often has about 20 elements, versus 6 - 12 for a lens with a fixed focal length. In comparison with one moving focusing group of elements in a fixed lens, a zoom has a moving focusing group, an element or several responsible for changing the focal length, and a compensating element is often added to them. Increasing complexity leads to increased scatter from specimen to specimen. Increased complexity leads to increased variability.

Let's look at the MTF cards of several quality prime lenses. These are maps of 9 real lenses tested using the method described above. I’ll add (because someone will definitely notice) that these are f/2.8 lenses, not f/1.4. No f/1.4 lens can resolve 30 pairs of lines so well. By the way, one copy from this group was dropped during rental, but “there was no visible damage.” Can you guess which one?

Calming blue means razor sharpness.

I think you noticed that the central lens in the right column does not look the best (this can be seen when compared with the others). If you look closely, you'll notice that the lens lower in the left column also has an area where it's not quite sharp. All others perform the same, and the small differences detected by the test bench are not noticeable even on the best test patterns.

If you ask me to send you a really good copy of this group of lenses, I will, without a shadow of a doubt, choose any of those located diagonally from top left to bottom right. (I’ll make a reservation right away so as not to return to this: believe me, if you estimate my labor costs for testing 9 lenses just to choose the best one, then you won’t be able to afford it). Even if I send you one of the other three copies, the Yuna card of which is missing yellow, I am more than sure that you will not feel the difference in real pictures.

Now about zooms

Let's look at the cards of several copies of good, expensive (priced at $2000) zoom lenses. You probably already realized that the difference from instance to instance, even with a good zoom, will be greater than with a prime lens. But have you ever thought that zoom needs to be tested at several focal lengths? We are used to evaluating lenses in terms of “good / bad copy”. This works with primes, but is not always applicable to zoom lenses.

I present the results of tests of eight copies of the 70-200mm f/2.8 lens, carried out at three focal lengths.

I warned you that the truth would be uncomfortable. But everything will be fine. Exhale.

Firstly, I assure you that this picture is not unique to this lens, this range of focal lengths or anything else. We've tested thousands of zoom lenses. Everyone's behavior is similar with very rare exceptions. Some are generally harsher. Some work better at one end of the focal range. Good performance of a specimen at one focal length does not mean a similar result at another focal length. However, I will add that a failed result at one focal point actually suggests poor performance at others.

Let me remind you that the optical test bench makes the most minor deviations visible. I repeat: the yellow-green areas will look a little soft when checked with test patterns, but in real photographs they will not be noticeable. Red ones will be noticeable. If you look closely, you will notice that lens No. 7 at a focal length of 70 mm is slightly worse on one side compared to the other. But the red areas are located at the edge of the frame and, say, a sports photographer or a portrait photographer who places the subject in the center, this will not interfere and they simply will not pay attention.

The thing is that even a good example of a zoom lens can be slightly decentered at one focal length, have a slightly tilted element at another and tilted in the other direction at a third. Take a closer look, you will notice.

For example, if you had the opportunity to compare copies No. 6 and No. 4 side by side, then you would definitely choose No. 6 - it is better than its rival at 200 mm focal length. But without that comparison, you'll probably rate #4 as decent. The owner of example #6 would rate the lens as much sharper at 200mm than at 70mm, and the owner of #4 would claim that it is slightly sharper at 70mm. The owners of No. 1 and No. 8 would join the dispute and call their opponents incompetent photographers, because the lens clearly works the same across the entire focal range. The owner of #8 will probably be happy with his lens unless he gets to compare it to #1.

Wait to draw conclusions, we only considered the sagittal graph. And it’s worth looking at the tangential one (or the astigmatism graph showing the difference between the first two). Let's say from the maps above, No. 3 looks like one of the leaders at 200mm focal length, but if you look at the astigmatism map, it will be one of the underdogs at that focal length.

Understand correctly, zooms are by no means terrible and suck. These are excellent and very convenient lenses. But once you know the compromises that go into designing them, you'd be as amazed as I am that they can be so good at these prices. I will add that based on images posted online by forum fighters with a resolution of 800 or 1200 pixels on the long side, you will not only not be able to see the difference between zoom lenses, you will also get confused between zoom and prime.

I just want to emphasize that, in general, zoom lenses have greater variation from one example to another, plus each instance of a zoom lens will also differ at different focal lengths. These are the laws of physics and the inevitable tolerances of mass production. The more variables in the lens, the greater the difference and deviation. That said, are zoom lenses any good? Without a doubt, yes! Can they match the quality of fixes? No. But even the best prime lens will not give you the convenience of changing the focal length. Each tool has its own tasks.

What are the conclusions?

There are no stupid questions. But there are stupid comments on forums. I'll try not to give a reason.

There are few conclusions, rather information that reminds us of reality. Here are a few points for photographers:

1. At comparable aperture values, even an excellent zoom cannot compare with a good prime lens, but it will be convincingly good, especially in the center of the frame.
2. Zooms are characterized by greater scatter from specimen to specimen, which is superimposed by the difference at different focal lengths. Ask me about the best zoom lens and I will inevitably ask: “Which focal length?” After all, the sharpest at 200 mm may not be the best at 70 mm.

Now about testing. I have to say: testing a single copy of a zoom lens is often simply pointless. Differences that are barely noticeable in real photographs stand out during testing. If someone were to test specimen No. 6 from our group, the numbers, and most importantly, the conclusions would be seriously different from those that would have been made when testing specimens No. 1 or No. 8.

A certain reviewer tested one copy of the zoom lens and gave it the highest rating for himself. Readers disagreed, argued with this assessment and asked me what I thought about it. This article is an attempt to explain why I see no point in getting involved in such disputes. An attempt to fit something as multifaceted as the operation of a lens with variable focal lengths into one single figure, and even after testing one single copy, has no scientific meaning or value. And I don’t care what rating is awarded - 3.1415926, 2.718281828 or 1.61803398. Unless the rating is 42. Then it will make sense.

It was funny. It's time to laugh. And eat an avocado.

Roger Cicala and Aaron Closz

Another translation of an article by Roger Cical from Lenzrentals.com. The translation was made for www.photogora.ru, but let it be present in Vlador as well.

It’s interesting when the scientific intersects (although perhaps “collides” would be more appropriate) with the creative. The scientist states: “Facts are more important than feelings.” The Creator objects: “Only my vision and design matter.” This is exactly the case in fine art. Whether a photographer or videographer achieves the intended shot is the yardstick, and the equipment used is secondary. That's why I don't argue when an artist tells me that all the tests in the world can't influence his choice of equipment. I accept his words that “this” lens is perfect for him.

But, while not challenging the right of shooters to have their own opinion about what equipment is suitable for them, I continue to believe that inaccurate information and lack of knowledge are harmful. So I'm going to tackle a recurring statement online that drives my inner scientist into a rage: This zoom is as good as a prime. (And following from the first one - give me the best copy of this zoom).

We will use a scientific approach, which involves familiarity with my testing methods and interpretation of results. (Without a scientific approach, I would simply state that this lens scored 82.7 in our rating, the meaning of which you do not understand, and the other - 79.2, and the article would be short, which our editors like so much. By the way, the editors hate me ).

Let's start with MTF charts, which I know many people don't understand and refuse to learn to understand. This part will be mercifully short, and then we will move on to the long-awaited pictures. Just be patient, I’ll make it easier for you by using our experimental method of subliminal encouraging text: it works unnoticed, but the positive charge goes straight to the subconscious, instilling a lasting feeling of well-being and achievement of goals.

The science has started, but so far without mathematics, so we’ll be tolerant.

You can do it, I promise.

You've probably seen MTF charts. Even if you don't understand them, I think you have the idea that the higher the lines on the graph, the better. You've probably already evaluated lenses by comparing the placement of lines on graphs. MTF graphs show the average performance of real lenses (if the graphs were created by Zeiss, Leica or myself), or a computer model of the theoretical best possible scenario (for all other graphs). The graph shows how half of the lens performs, from the center (left side of the graph) to the edge of the image (right side).

Here are the MTF graphs of the two lenses, from which we can conclude that the resolution of the left one is higher than that of the right one. The graphs say a lot more, but let’s limit ourselves to the main thing - the higher the line on the graph, the sharper the lens.

There is one “but”: the graphs display either the average performance of many lenses, or ideal performance simulated by a computer. Now we take on testing. Firstly, you see that our graph shows not half, but the entire field of the lens. The center of our image is in the center, and not on the left edge of the graph. Secondly, it is immediately clear that one side is clearly different from the other. With mass production, it is impossible to make everything perfect. By the way, this is a chart of the MTF model, the average chart of which was above on the left.

It can be seen that the left side is different from the right. But if one side is different from the other, how do the top and bottom of the frame relate? Or corner-to-corner? If we want to truly test a lens, we need to take readings multiple times, rotating the lens to get data from different areas of the frame. Here's a graph of our lens tested at four rotations.

We're almost done with the boring explanations. There is very little left. You can do it!

This is a graph plotted over four rotations. You could do it at 8 or twelve, but the pictures will be very small, and you’ll already be bored. You’re probably thinking: “Just say 79.2 out of 100 in a simple way instead of all this drudgery!”

What if, instead of lines, we graphically display how MTF is distributed over the surface of the frame? Below is a map of the sagittal MTF, where the area of ​​greatest sharpness is shown in blue, slightly worse in yellow, and slightly worse in red (in this case it is absent) where the sharpness is not very good.

Do you agree that this is much clearer? It's immediately clear that our test unit is well centered (highest MTF in the center) and the right side is slightly less sharp than the left. More details later, but if you test it yourself, you won't notice such a minor difference. The MTF test bench is much more sensitive than any camera (at least to date).

Maps of other lens metrics can be made. Below, for example, is a map of the astigmatism of the same lens.

MTF is over for today. Now you can look at cute color pictures, achieving peace and relaxation.

It is obvious that the lens in question has increased astigmatism on the right edge. Such cards are an easy and reliable way to evaluate a specific lens at a glance. There will be a whole bunch of these pictures later, so I tried to explain how we get them.

Will this be noticeable in real photographs?

I already said that our optical test bench is much more sensitive than a camera. It distinguishes very minor deviations, which in real photographs will be masked by other variables present in the frame - lighting, focusing, location of objects and many others. Serious deviations will be noticeable. How serious? Let's look at the cards of two copies of the same lens model, one of which meets all the requirements, the other is worse. (Actually, it's not bad at all and the only worrying area is the red area at the bottom). If you were to shoot with this lens, you would most likely rate it “good” or “a little soft.” If you shot it second, you would describe it as “outstanding.”

(The map appears cropped compared to the one shown above. This lens has a built-in limiter to reduce reflections, and the image it produces is a rectangle, similar to a camera sensor, rather than a circle, like the one above.)

Olaf Optical Testing, 2017

I understand that it’s more pleasant to evaluate lenses based on colorful photographs, but a stage shot has too many variables, and we strive for science. You'll have to make do with photographs of test tables.

Let's compare the top part above the center of the frame, which was excellent on the right lens and good on the left. To fit 100% of the crop into the format of this unfortunate blog, you will have to place them on top of each other: the right lens on top, and the left one on the bottom. These are crops of RAW images of high-quality test patterns taken on a 36-megapixel camera, without sharpening. On a camera with a higher resolution the difference will be more obvious, with a lower resolution it will be less noticeable, but for our purposes these images will be suitable.

I can see the difference, and I think you can too. If I had shot in JPEG rather than RAW, the difference due to in-camera sharpening would have been less noticeable. Don't forget that test charts are easier to evaluate than photographs, and in real photographs the difference would only be noticeable in a side-by-side comparison. If you bought the lens, the map of which is shown on the left, you would hardly complain about blurriness at the top of the frame, especially after some post-processing and when posting JPEGs with a resolution of 800 pixels on the long side.

Let's look at the lower left area. As before, the right lens is on top and the left is on the bottom.

Here the difference is greater. It can be assumed that there is something wrong with this angle. Tangential test lines (those from top left to bottom right) appear gray on gray, indicating low detail. That's it, let's limit ourselves to this. I just wanted to show that our MTF maps reflect the real state of affairs.

How long? Isn't it time to talk about zooms?

It's coming soon, my patient friends. We're done with the conceptual part, there's not much left to do.

Many people know that a zoom, even if comparable to a prime lens in terms of sharpness in the center of the frame, can rarely boast the same sharpness at the edges and corners of the frame.

But few people think about how much more complicated a zoom lens is than a prime lens. The optical design of a zoom often has about 20 elements, versus 6–12 for a lens with a fixed focal length. In comparison with one moving focusing group of elements in a fixed lens, a zoom has moving ones: a focusing group, an element or several that are responsible for changing the focal length; a compensating element is often added to them. Increasing complexity leads to increased scatter from specimen to specimen. Increased complexity leads to increased variability.

Let's look at the MTF cards of several quality prime lenses. I show maps of 9 real lenses tested using the method described above. I’ll add (because someone will definitely notice) that these are f/2.8 lenses, not f/1.4. No f/1.4 lens can resolve 30 pairs of lines so well. By the way, one copy from this group was dropped during rental, but “there was no visible damage.” Can you guess which one?

Calming blue means razor sharpness.

I think you noticed that the central lens in the right column does not look the best (this can be seen when compared with the others). If you look closely, you'll notice that the lens lower in the left column also has an area where it's not quite sharp. All others perform the same, and the small differences detected by the test bench are not noticeable even on the best test patterns.

If you ask me to send you a really good copy of this group of lenses, I will, without a shadow of a doubt, choose any of those located diagonally from top left to bottom right. (I’ll make a reservation right away so as not to return to this: believe me, if you estimate my labor costs for testing 9 lenses just to choose the best one, then you won’t be able to afford it). Even if I send you one of the other three copies, the card of which does not have yellow on the card, I am more than sure that you will not feel the difference in real pictures.

Now about zooms

Let's look at the cards of several copies of good, expensive (priced at $2000) zoom lenses. You probably already realized that the difference from instance to instance, even with a good zoom, will be greater than with a prime lens. But have you ever thought that zoom needs to be tested at several focal lengths? We are used to evaluating lenses in terms of “good / bad copy”. This works with primes, but is not always applicable to zoom lenses.

I present the results of tests of eight copies of the 70-200mm f/2.8 lens, carried out at three focal lengths.

I warned you that the truth would be uncomfortable. But everything will be fine. Exhale.

Firstly, I assure you that this picture is not unique to this lens, this range of focal lengths or anything else. We've tested thousands of zoom lenses. Everyone's behavior is similar with very rare exceptions. Some are generally harsher. Some work better at one end of the focal range. Good performance of a specimen at one focal length does not mean a similar result at another focal length. However, I will add that a failed result at one focal point actually suggests poor performance at others.

Let me remind you that the optical test bench shows the most minor deviations. I repeat: the yellow-green areas will look a bit soft when checked with test patterns, but in real photographs they will not be noticeable. Red ones will be noticeable. If you look closely, you will notice that lens No. 7 at a focal length of 70 mm is slightly worse on one side compared to the other. But the red areas are located at the edge of the frame and, say, a sports photographer or a portrait photographer who places the subject in the center, this will not interfere and they simply will not pay attention.

The thing is that even a good example of a zoom lens can be slightly decentered at one focal length, have a slightly tilted element at another and tilted in the other direction at a third. Take a closer look, you will notice.

For example, if you had the opportunity to compare copies No. 6 and No. 4 side by side, then you would definitely choose No. 6 - it is better than its rival at 200 mm focal length. But without that comparison, you'll probably rate #4 as decent. The owner of example #6 would rate the lens as much sharper at 200mm than at 70mm, and the owner of #4 would claim that it is slightly sharper at 70mm. The owners of No. 1 and No. 8 would join the dispute and call their opponents incompetent photographers, because the lens clearly works the same across the entire focal range. The owner of #8 will probably be happy with his lens unless he gets to compare it to #1.

Wait to draw conclusions, we only considered the sagittal graph. And it’s worth looking at the tangential one (or the astigmatism graph showing the difference between the first two). Let's say, according to the maps above, the third number looks like one of the leaders at a focal length of 200 mm, but if you look at its astigmatism map, then it turns out to be one of the outsiders at this focal length.

Understand correctly, Zooms are by no means “horror and suck.” These are excellent and very convenient lenses. But once you know the compromises that go into designing them, you'd be amazed, as I was, that they can be so good at these prices. I will add that based on images posted online by forum fighters with a resolution of 800 or 1200 pixels on the long side, you will not only not be able to see the difference between zoom lenses, you will also get confused between zoom and prime.

I just want to emphasize that, in general, zoom lenses have greater variation from one example to another, plus each instance of a zoom lens will also differ at different focal lengths. These are the laws of physics and the inevitable tolerances of mass production. The more variables in the lens, the greater the difference and deviation. That said, are zoom lenses any good? Without a doubt, yes! Can they match the quality of fixes? No. But even the best prime lens will not give you the convenience of changing the focal length. Each tool has its own tasks.

What are the conclusions?

There are no stupid questions. But there are stupid comments on forums. I'll try not to give a reason.

There are few conclusions, rather information that reminds us of reality. Here are a few points for photographers:

1. At comparable aperture values, even an excellent zoom cannot compare with a good prime lens, but it will be convincingly good, especially in the center of the frame.
2. Zooms are characterized by greater scatter from specimen to specimen, which is superimposed by the difference at different focal lengths. Ask me about the best zoom lens and I will inevitably ask: “Which focal length?” After all, the sharpest at 200 mm may not be the best at 70 mm.

Now about testing. I have to say: testing a single copy of a zoom lens is often simply pointless. Differences that are barely noticeable in real photographs stand out during testing. If someone were to test specimen No. 6 from our group, the numbers, and most importantly, the conclusions would be seriously different from those that would have been made when testing specimens No. 1 or No. 8.

A certain reviewer tested one copy of the zoom lens and gave it the highest rating for himself. Readers disagreed, argued with this assessment and asked me what I thought about it. This article is an attempt to explain why I see no point in getting involved in such disputes. An attempt to fit something as multifaceted as the operation of a lens with variable focal lengths into one single figure, and even after testing one single copy, has no scientific meaning or value. And I don’t care what rating is awarded - 3.1415926, 2.718281828 or 1.61803398. Unless the rating is 42. Then it will make sense.

It was funny. It's time to laugh. And eat an avocado.

Roger Cicala and Aaron Closz

• #1

Which type of lens is better - prime or zoom? This is one of the most discussed topics in photography. Some of you will choose a zoom lens, while the other will choose a prime lens. It depends on what and where you are going to photograph. It is very important to know what these two types of lenses are and which one should be used in a given situation. This article will help you in this area.

What is a prime lens?

A lens with a fixed focal length is known as a prime lens. Therefore, if you want to change the view of the frame, then you should move further or closer from where you are standing now. The focal length is fixed, there is no zoom ring on the lens.

There is a wide range of prime lenses on the market, from wide-angle lenses (such as 14mm and 24mm) to mid- and long-range telephoto lenses (such as 135mm and 400mm).

Fixed lensSigma20 mm.

What is a zoom lens?

A lens with a variable focal length range is known as a zoom lens. With this lens, you don't have to move around, and the zoom ring allows you to get a narrower or wider angle of view. Thus, using a zoom lens, you can change the focal length to adjust the viewing angle.

There is a wide range of zoom lenses, be it a wide angle lens (like the 12-24mm or 16-35mm), a telephoto lens (like the 70-200mm, 100-400mm and 150-600mm) or an all-purpose zoom lens (like the 18-300 mm and 24-105 mm).

Zoom lensTamron18-200 mm.

Benefits of using prime lenses

Wide diaphragm With smaller costs

One of the biggest benefits of using a prime lens is that you can use wide apertures (small f-numbers) such as f/1.8 and f/1.4 at a reasonable cost. For example, the Canon EF 50mm f/1.8 STM Lens (only $125) and the Sigma 85mm f/1.4 DG HSM Art Lens ($1,199 compared to Nikon's $1,599 or Canon's $1,899 version). Whereas a zoom lens like the Canon EF 70-200mm f/2.8L won't allow you to shoot wider than f/2.8 and will burn a hole in your pocket (around $2000).

Shallow depth of field

A prime lens allows you to use an aperture as low as f/1.2 or f/1.4, thereby providing a truly shallow depth of field. By using such a wide aperture, you will get more bokeh, which means the subject will be in focus and the background/background will be blurred. In comparison, a zoom lens will not allow you to go wider than f/5.6, f/4 or f/2.8, which will result in a greater depth of field.

Therefore, if you plan to achieve a shallow depth of field (more bokeh), then a prime lens will suit your needs.

Photo onf/1.4 using lensSigma20 mmf/1.4 DG HSM.

Best photos in low light conditions

As mentioned above, a prime lens allows you to use aperture values ​​such as f/1.2-1.8, while allowing more light into the camera. When shooting in low light conditions with a prime lens, you can use a faster shutter speed, as it will give an advantage of 3-4 steps of light (f/1.4 > f/2 > f/2.8 > f/4 > f/5.6 – 50 mm f/1.4 gives 4 stops more than a standard f/5.6 lens) compared to a zoom lens.

So, when using a zoom lens at f/4, it will give a shutter speed of 1/20, and using a prime lens at f/1.4, you can set the shutter speed to 1/160. If you're in low light conditions and don't have a tripod, a prime lens will give you the added benefit of letting more light into the camera.

Better sharpness and image quality

Prime lenses have fewer elements that are placed inside them to perform specific functions. This is why a prime lens produces fewer optical defects such as chromatic aberration and distortion, which improves image quality.

The number of elements in a zoom lens is larger because it must provide variable focal lengths, affecting sharpness. However, day by day, zoom lenses are getting better in terms of image quality and sharpness to match prime lenses.

Advantages of a zoom lens

Versatility

One of the greatest advantages of using a zoom lens is that it allows you to change the focal length without changing the lens. The zoom lens provides a range of different focal lengths, which can be adjusted using the zoom ring. This range depends on the lens model. Here are some of them: 18-55 mm, 16-35 mm, 24-70 mm, 70-200 mm, 100-400 mm and 18-300 mm. Using a zoom lens, you can go from a wide angle to a telephoto view without changing lenses.

Therefore, if your shooting requires switching between different focal lengths, then it is better to choose a zoom lens to save your time and not miss important moments. In wedding photography, sports photography, and also when traveling, it is worth using a zoom lens, since changing prime lenses, you may miss the moment.

This image shows the focal length range of the lensTamron18-200 mmF/3.5-6.3 Di II V.C..

Portability

A zoom lens such as the Canon EF 70-300mm f/4-5.6 combines five prime lenses into one, as it covers the most commonly used focal lengths such as 85mm, 100mm, 135mm, 200mm and 300mm. Imagine how much more convenient it is to carry one lens instead of five. While a zoom lens won't allow you to use a wide aperture or take amazingly sharp photos like a prime lens, it will allow you to go light. Now it's up to you whether to take advantage of the portability of a zoom lens or carry the extra weight if you don't want to compromise on quality.

If you travel frequently, like to be lightweight, and can afford to compromise a bit on image quality and wide aperture shooting, then a zoom lens may be the best choice for you.

All included

As stated in the example above, the Canon EF 70-300mm f/4-5.6 IS USM Lens combines five lenses (or more). So now if you do the math, a $449 zoom lens will allow you to use any focal length between 70mm and 300mm. While buying five or more prime lenses you will spend about $4000.

A zoom lens will be the ideal choice for you if you have just started learning photography and want to try yourself in different genres. First, buy a decent zoom lens, such as an 18-55mm, 18-300mm, 55-250mm, or 70-300mm. Once you decide on the genre of photography you want to work in, you can buy the next lens that suits your needs.

Conclusion: prime or zoom lens?

There is no doubt that prime lenses excel when it comes to sharpness and image quality. However, zoom lenses are constantly being improved, although this is not yet enough. Although some premium zoom lenses such as the Canon EF 70-200mm f/2.8L and Canon EF 24-70mm f/2.8L II USM produce images with brilliant sharpness and less chromatic aberration.

If you want beautiful bokeh that can only be achieved at a wide aperture, then you should choose a prime lens. It will give you the opportunity to choose an aperture such as f/1.2, f/1.4 or f/1.8. Likewise, when shooting in low light, a prime lens will give you the added advantage of using a faster shutter speed, which will make your photos sharper.

But if you are a frequent traveler or are not familiar with the area, then using a zoom lens will be a safer option as it is versatile and portable. Even for weddings or event coverage, you can't rely on a prime lens as there are restrictions on movement, so using a zoom lens would be a smarter choice.

This type of lens is often preferred by beginning photographers. Judge for yourself: universal zooms have a range of focal lengths covering the area of ​​wide-angle, standard and telephoto lenses. It would seem, what else does a photographer need?

But in this world there is nothing truly universal. Such models are characterized by low aperture, and this can create problems when shooting not only indoors, but even outdoors on a cloudy day. The optical quality of universal zooms is also not always up to par. Be prepared for the fact that photos taken with this lens may not be sharp enough. This will be especially noticeable on cameras with a high matrix resolution. If you don’t shoot in poor lighting conditions, don’t have very high demands on photo quality, and prioritize the ease of use of the lens, then a universal zoom will be the best solution for you. Having bought one such lens, you can forget about the need to purchase other optics. It will replace two or three lenses with a smaller range of focal lengths, but better optical characteristics.

Standard zoom

Over the many years of existence of SLR cameras, the requirements for this class of lenses were formulated quite clearly: focal length from wide-angle to moderate telephoto, plus high aperture. Many photographers almost always have this lens installed on their camera, as it allows them to work in most genres: landscape, portrait, everyday photography, reportage. Due to the relatively low zoom factor (3-4x), it is possible to achieve fairly high optical quality. However, the price of the best representatives of this class is often comparable to the cost of the camera, and sometimes even exceeds it. The most expensive models are designed for use with full-frame professional cameras. Their focal length range is usually from 24 to 75 mm, and their aperture is f/2.8.

For cameras with a reduced matrix size, cheaper, but often no less high-quality, models have been developed in recent years. Their focal length range is typically between 18 and 50mm (so the equivalent focal length is close to the 28-75 range).

Also, the model ranges of photographic equipment manufacturers usually contain budget lenses with similar focal length ranges, but with lower aperture (constant f/4 or variable up to f/4.5). With rare exceptions, the quality of these models is lower than the top ones, but the cost is significantly lower.