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The image here was shot at 24mm focal length. The wide angle distorted the vertical lines by bending them inwards towards each other.

Pincushion distortion is the opposite of barrel distortion. It causes straight lines to appear curved inward, creating a pinched or cushion-like effect. This type of distortion is often seen in telephoto lenses.

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As you increase the ISO on your camera, you introduce noise into the sensor. Therefore, high ISOs are a type of distortion.

To fully understand wide-angle distortion, we first need to understand the concept of wide-angle itself. To do this, we also need to know about lens focal length.

So, a cropped sensor’s equivalent standard field of view will be 50 / crop factor. So, for our 1.5x, it will be 50 / 1.5 = 33mm.

Noise is more obvious in the darker areas of your scene, too. Noise can be reduced in post-processing, and there is also some great software out there, such as Topaz Denoise, that does an excellent job.

The value of the MTF at frequency 0 is always 100% since a flat field is considered to have been reproduced perfectly, with no intensity loss. Attenuation due to lens transmission is measured separately.

The standard field of view for a digital SLR, mirrorless, or 35mm SLR film camera is 50mm. This is equal to what we see with our eyes. Anything below 50mm = wide angle. Anything above 50mm = telephoto.

Because of field aberrations (such as field curvature), the value of the limiting resolution and acutance depends on the field position.

You can use the wide angle effect to accentuate interesting foreground objects or scenery in a landscape, such as rocks, rivers or roads. The classic use would be to get down low in the middle of a road to make the start super wide and then have it taper off in the distance to some beautiful mountains.

Ian Middleton is a travel and landscape photographer and writer. He is the author of several books, including a practical guide to photography. His photography has been used in numerous publications worldwide and is sold as high-quality wall art online.

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We map the acutance on a color scale as a function of focal length and aperture value. We make measurements for several field positions.

Vignetting is darkening in the corners of an image. It can be caused by limitations in the lens design or when using filters or lens hoods that obstruct some of the light entering the lens.

Fisheye lenses produce extreme barrel distortion, resulting in a circular or hemispherical projection of the scene, like looking into a fishbowl. Therefore, this effect is intentional and used for creative or artistic images.

When they do, it’s called a full-frame sensor (i.e., equal to 35mm film). Other sensors are smaller and commonly known as cropped sensors. These sensors have a crop factor, for example, 1.5x crop factor.

The images below show the difference between using wide angle and telephoto on the same scene. The first was shot standing close to the grass with a 24mm focal length, while the second was shot from across the road using a 105mm focal length.

Every lens is different, but the rule of thumb for avoiding diffraction is to set a maximum aperture of F11 on a crop sensor and F16 on a full-frame.

Real estate photographers use wide angles to ensure the whole room is captured in the photo, but the wide angle also makes rooms appear much bigger.

However, while in many situations that may be true, in others, it is not. Distortion can also be used for creative effect. It can enhance or add drama to an image or scene.

If you wish to avoid or minimise this effect, you must move back and higher to shoot more straight at a higher perspective.

However, there are several distinctive features of distortion caused by the technical aspects of a lens. And these are what we will look at more specifically in this article.

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You can use this effect to accentuate features of a subject, add or create drama to a scene or make things look funny. Here are some uses:

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DSLR lenses usually have a radial symmetry, which means that field dependency can be summarized by the MTF at different distances to the image center.

In the case of wide angle, the distortion effect is warping or bending the perspective of objects in our scene. Wide angle stretches our field of view beyond what is considered normal and thus stretches objects within the composition.

This warping is more evident around the edges of our frame, on larger objects or ones closer to the camera. It also makes foreground objects larger and distant objects smaller.

For the DxOMark sharpness score, we compute MTF in horizontal and vertical directions by examining the spatial response of the camera to a perfect edge. This measurement follows ISO standard 12233.

The term “distortion” invokes a feeling of something bad in photography, and you could be forgiven for thinking it’s undesired.

Wide angles can also emphasise dramatic, stormy skies with interesting cloud formations. They are also great for reflections at sunset, where you can go wide and capture a great flaming sky reflected in a large body of water like a lake.

In an optical zoom, the distance between the lens and the focal plane is known as the focal length, as illustrated here:

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The DxOMark score for Sharpness is based on the Perceptual Megapixel (P-Mpix) concept that weights the Modulation Transfer Function (MTF) of the lens with the human visual acuity. Read more about Perceptual Megapixels.

The other distorting effect is that the lower half of the building, which is closer to the camera, has been stretched wider and made larger in the frame, whereas the more distant object, the top of the tower, has been shrunk and looks much smaller.

It can manifest as both lateral chromatic aberration (at the edges of the frame) and longitudinal chromatic aberration (in front of or behind the focal plane). This is easily corrected in post-processing.

There are several types, so in this guide to lens distortion in photography, we will look at each one and learn when and how to avoid it or use it creatively.

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The effect is worse on cropped sensors. Therefore, if using a full-frame camera, you can typically use a smaller aperture than a cropped sensor without the risk of diffraction.

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How bad this noise can be depends on the camera you use. Higher-end cameras perform better at high ISOs than cheaper ones. Also, camera manufacturers are making massive improvements in this area.

Sharpness is based on the MTF measurement. Let’s start with a practical measurement experiment to help describe what MTF is. If we look at a series of black and white stripes with varying spatial frequency and fixed contrast (same reflectance ratio between black and white, independent of the spatial frequency), we can see that the image of high-frequency stripes has a lower contrast than that for low-frequency stripes. For very high frequencies, the image eventually becomes (almost) uniform, with an intermediate level between black and white, which our eyes perceive as a shade of gray.

In the telephoto, the grass is a bit smaller, but more importantly, the church now looks bigger in the picture and closer to the grass.

The MTF precisely describes the contrast attenuation: for each spatial frequency, the MTF plots the ratio of the output modulation versus the test object modulation.

That said, you will lose sharpness and end up with a softer image. So be sure to only use a high ISO whenever there is no other choice.

Lens diffraction is a type of distortion caused by small apertures. It affects image sharpness and detail, and it’s important to understand, especially when choosing aperture settings.

The dictionary definition of distortion is—“The act of twisting or altering something out of its true, natural, or original state.”

Aside from injecting water into the burger to puff it up a bit, they also get right up close with a wide angle to make the meat look much bigger than it is.

When you zoom in, you isolate a part of the scene and make it look artificially larger. But the other effect is that it can make objects seem much closer and bigger in relation to each other.

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Ever seen those photos of that big juicy hamburger, only to find that when you buy one and open the package, it’s a shrivelled piece of meat in a big bun?

If you stand there looking with your eyes, there would be a similar effect, only not as pronounced. So, the wide-angle accentuates the distorted perspective.

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When the aperture is set to a very small size, such as F22, light waves passing through it can be bent when they encounter an obstacle, like a small aperture.

You may have seen those classic images of a rabbit or a stag with a giant moon behind. This is not done using Photoshop but using a 1000mm focal length.

An objective measure of sharpness which takes into account the sensitivity of the human visual system to specific spatial frequencies and the viewing distance of an image. Edge acutance refers to the ability of a photographic system to show a sharp edge between contiguous areas of low and high illuminance. Texture acutance refers to the ability of a photographic system to show details without noticeable degradations.

We plot the acutance as a function of the radial field position, taking into consideration horizontal and vertical directions. We make measurements for several focal lengths and aperture values.

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Sharpness is a subjective quality attribute of an image or a lens. Sharpness indicates the visually perceived quality of details of an image or details reproduced by a lens. It is associated with both resolution and contrast of reproduced details (within an image or by a lens).

This type of distortion causes straight lines to appear curved outward as if they were wrapped around the surface of a barrel. It is most commonly associated with curvilinear wide-angle lenses and can make images look bulging in the centre.

Now, you could argue that every image we take in photography does just that. There is course, an element of truth to this.

This causes them to spread out or interfere with each other, reducing image sharpness and producing a soft or blurry image.

As seen above, you can shoot from below to accentuate the height of a building or multiple buildings in a city to create a sense of drama.

The resolution of a camera is defined by the size of the smallest detail that the camera can optically discriminate. ISO standard 12233 defines the limiting resolution as the first frequency such that the contrast attenuation is 95% (hence a MTF value of 5%). In practice, this value is very small and is also sensitive to measurement noise