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Beginners Guide to Camera Lenses: Parts, Functions and Types

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All photographers know what a camera lens is. If the camera is the ‘brain’, then the lens is the ‘eye’. It lets us view and capture our environment.

Some photographers find that the lens is more important than the camera. Others believe that the camera body functions and limitations are more important.

Either way, read on to find out all the information you could possibly know about camera lenses.

Three different types of camera lenses on a black background

Isn’t a Lens Only as Good as the Camera Body?

A camera lens is a very special item. It’s absolutely necessary to capture great images.

You could use a pinhole and get great results. But you would have little to no control over the final image.

Camera lenses, like it or not, are the most important part of your kit.

A camera lens denotes the aperture range you can use, the possible depth of field and the focusing distance. A camera can’t focus without a lens or capture any image at all.

You can, however, capture images without a camera body if you were so inclined.

I know camera bodies are important. They allow other settings such as ISO and shutter speed. They influence the quality of the image through resolution. But they aren’t as important as lenses.

The first digital camera I ever owned was a Canon EOS 400D (Rebel XTi / Kiss X). The lens I had was not very special. It was the actual kit lens that came with the camera. This was 13 years ago.

I then picked up a Canon 7D just over 8 years ago, and have used a Canon 5D Mark III ever since.

The lenses and camera bodies were different, but there was no way I could tell which camera I used for any given image. Especially not just by looking at them.

I could tell you which lens I used though, based on crop factor, focus and depth of field.

A close up of a photographer playfully throwing a camera lens into the air

Are Lenses Really That Important?

As long as you get along with your lenses, you’ll find that you update your camera body rather than your glass. The cameras change in resolution, features and a great many other ways.

The lenses you own today could well be the ones you own for the longest period of time. If you look after them, they will last a lifetime.

A camera has shutter actuations, meaning a shelf life. But once you find that great lens, you’ll want to hold on to it.

As I said before, many photographers chase glass. They realize that to get the best out of a scene, the glass is the most important. They then build their system around it.

One of the biggest debates between Canon and Nikon is about lenses. Nikon is said to have higher quality glass, creating a better overall image. That isn’t to say that Canon doesn’t have great lenses or other benefits.

There are also huge conversations and debates over third-party lenses, but we’ll delve into that later.

If you keep hold of your lenses, you’ll notice they will get slightly better with every camera upgrade.

The camera helps bring out the most of the lens. Better colors and less noise mean improved output and a happier photographer.

A close up of different camera lenses

What Does a Camera Lens Do?

A lens is a device that contains lens elements. These elements are shaped glass pieces that bend light in specific ways. Each element within the lens has a different function, and they work together in harmony.

Their task is to create a sharp image on your film or sensor.

They do this by helping light beams focus. It sounds simple, but designing and building these lenses is very complicated. Science and mathematics all the way.

One of the biggest challenges with a lens is the need for sharpness across the entire width of your scene. This includes the corners.

And then you also have zoom lenses. These have to focus light rays to converge and focus at an array of different focal lengths. We won’t go into that here. Just know this – lens designers and creators are amazingly smart.

A photographer shooting with a Canon DSLR in a street - understanding the camera lens

Parts of a Camera Lens

Here we have the anatomy of a lens. As you can see, there is a lot of glass that makes up a lens.

A diagram showing the interior the anatomy of a camera lens

Some of these pieces are fixed to the barrel of the lens, and others are movable. These allow you to zoom, focus or assist in image stabilization. We will look at this in greater depth later on in the article.

The outside of the lens is something we are more or less familiar with.

Do you know what all the controls, attachments and text mean? Lenses differ between manufacturers, but the general information is the same.

A Lens is the Sum of Its Parts

This information is somewhat different between analog and digital systems.

  • Focusing ring (both systems)
  • Zoom ring (both systems)
  • Focal length information (both systems)
  • Aperture size (analog)
  • Distance indicator (both systems)
  • Depth of field indicator (both systems)
  • Lens mount (both systems)
  • Image stabilization controls (digital)
  • Manual/Autofocus switch (both systems)

A diagram showing the exterior the anatomy of a camera lens

Focal Length Explained

One of the most important aspects of a lens is its focal length. The focal length and widest aperture are two of the most important reasons for buying a specific lens.

What Is Focal Length?

Focal length often confuses photographers, especially newbies. Let’s keep it simple.

When light travels through your camera, the image is flipped upside down. This is the same way our eyes see the world.

A diagram explaining focal length and how light passes through a camera sensor

Inside the camera is a pentaprism that flips the image the right way. As you can see from the image, there is an intersection inside the lens. This intersection is the convergence between the lines of light that we get from our subject.

A diagram explaining how a pentaprism works in a camera - camera lens guide

In optics, this crossing point is called the ‘nodal point’. The distance between this nodal point and your image sensor or film is the focal length.

A diagram explaining howa nodal point works in a camera - camera lens guide

Why Is Focal Length Important?

The focal length of a lens describes how wide its field of view is. This is what makes a lens wide, standard or telephoto.

Consider the placement of the converging nodal point. The closer it is to the imaging sensor, the smaller the object appears in the image.

A diagram explaining focal length and how light passes through a camera sensor - camera lenses explained

Imagine the nodal point was much farther away from the imaging sensor. This would make the subject seem much larger.

As you can see, a low focal length creates a wide field of view. Lenses with a low focal length are known as ‘wide angle‘ lenses.

The opposite is true too. A long focal length creates a narrow field of view. These lenses are known as telephoto lenses.

A diagram explaining focal length and how light passes through a camera sensor - camera lenses explained

Difference Between Zoom and Prime

Whether wide angle, standard or telephoto – every lens falls into one of two categories; zoom or prime. The first lenses only had a fixed focal length.

Engineers knew it would be a great idea to make them more versatile. Having one lens with an array of different focal lengths has benefits.

Photographic lenses were configured and created to allow the nodal point to move closer or further away from the sensor.

In doing this, they created the variable focal length – the zoom lens. The other lenses became known as prime lenses. And the rest is history.

A diagram showing how a zoom lens operates

Lens Apertures

Aperture is another reason why photographers choose one lens over others. The word aperture means opening, and describes the size of the hole in a lens.

This is where the light passes through, making its way to the camera sensor.

Apertures might seem a little strange. They are a fraction of the focal length of a lens. We see f-stops written as f/2 or f/11.

The ‘f’ in f-stop comes from focal length. The preceding slash is a mathematical expression of the pupil’s diameter.

If a lens’s focal length is 10 mm and its entrance pupil diameter is 5 mm, the f-number is 2.

The fractions are important here. If you are capturing a scene with a 100 mm focal length lens at f/2, the diameter of your lens is 50 mm across.

Likewise, if you’re shooting at f/4, then the diameter is 100/4 = 25 mm.

The f-number gets bigger but the aperture gets smaller. This is important, but normal as we are talking about fractions. F/2 is bigger than f/4, which is bigger than f/8.

How Do Apertures Affect Lenses?

A larger aperture (smaller f-stop number) means that more light passes through your lens. More light is better in low light situations.

When it comes to choosing a lens, the most important factor is the maximum aperture. This number is written on the lens, and included in the lens’ specifications.

The biggest-size aperture is an expression of how ‘bright’ the lens is. Brighter is better.

A diagram showing different f/stop numbers - camera lens guide

Lens Markings

The numbers you’ll find on a lens are all very important. the first number you’ll come across is usually the lens’ focal length. This number is represented in millimeters.

If you see one number rather than a range, it means you are holding a prime lens. It could say 24 mm, 35 mm, 50 mm, 85 mm, or something similar.

A focal length range will have two numbers separated by a dash. 24-70 mm is a good example and means you are holding a zoom lens.

A close up of lens markings on a sigma ap) DG lens

The second number you’ll find on a lens is usually the lens’s maximum aperture. If you have one number, it means your zoom lens has a fixed maximum aperture.

Prime lenses do not have a variable maximum aperture.

If you have two numbers separated by a dash, it means your zoom lens has a variable maximum aperture. It will look something like this ‘f/4-5.6‘.A flow chart explaining how to understand camera lens markings

Other Markings

There are other markings you might find on your lens.

  • ∞ – 0.5 m – Sometimes you may find an infinity symbol, then a dash and then a distance indicator. This is the operating range of the lens. This indicates the closest focusing distance of the lens. It can be in meters or feet, or even both.
  • IS/OIS/VR – This stands for Image Stabilisation, Optical Image Stabilisation or Vibration Reduction. This means that your lens has a built-in floating lens element, along with motors and electronics. These lenses sense and counteract any movement or shake.
  • Ø – The ø symbol on a lens is usually followed by a number. This is the diameter of the front of the lens. It will be useful in purchasing screw-in filters in the future.
  • Asph / ASP – This stands for Aspherical. It shows that the lens has non-circular lenses inside. These lens elements can be used to reduce spherical aberrations.
  • Macro / CRC (Close Range Correction) – This marking means the lens is specifically designed to be sharp at close ranges. These are great for photographing flowers, bugs, and other minute items. Not all macro lenses are the same, and some are much better than others.
  • USM/HSM/SWM – UltraSonic Motor, High-Speed Motor, and Silent Wave Motor are all ultrasonic vibration motors that allow you to autofocus faster. The ones used in higher-end products are much quieter than those in cheaper lenses.
  • DX (Nikon) / EF-S (Canon) – These lenses were specifically created for camera bodies that are smaller than full-frame. APS-C size sensors have a crop factor. These lenses give you a focal length, taking in the smaller sensor into account. These are smaller and lighter to their siblings, but can’t be used on full frame cameras.
  • Other – Lens manufacturers use a slew of markings on their lenses. Canon likes to mark their professional lenses with a red ‘L’, and Sigma uses EX for their expensive glass. They don’t mean anything special.

A photo of two DSLR camera with zoom lenses, outdoors on grass

Variable Aperture

We looked at the variable aperture briefly before. This is something you will come across when using zoom lenses, especially lower-end models.

Variable apertures are different maximum apertures (smallest f/stop) that your lens will use, depending on the amount of zoom you use to capture.

Remember that an aperture is the size of the hole in which the light passes through. It is expressed as a fraction of the focal length. For example, f/2 with a focal length of 300 mm is a 150 mm hole.

Aperture can cause some obstacles when it comes to zoom lenses. Let’s use the Canon EF 70-300 mm f/4-5.6 as an example of the maths. At 70 mm, you can use the f/4 aperture. 70 divided by 4 gives us 17.5 mm. 

By zooming all the way in, we go from a 70 mm to 300 mm focal length. The images you capture are magnified by 4.3%. At 300 mm, your maximum aperture is f/5.6, where the diameter is 53.57 mm.

But why can’t a telephoto lens be f/3.5 throughout the zoom range? At 300 mm, an f/3.5 aperture would be 85.71 mm. This is too big to fit into the slim body of the lens. Usually, there isn’t enough space for this wider aperture only in an exceptional telephoto lens construction.

Is It a Deal-Breaker?

Many photographers see these lenses as inferior and avoid them. But there is no reason to do so. These lenses, apart from offering great quality lens designs, give you a compromise.

Every lens is a compromise between every single one of its usabilities.

Non-variable aperture (fixed minimum aperture) lenses offer some great advantages. They are lighter and smaller than their counterparts, and therefore cheaper.

The other problem with variable apertures is that they are worse for low light conditions.

A chart showing how aperture and depth of field correspond

Focusing a Lens

All lenses have some sort of way to focus the scene in front of you. If you’re looking for a technical definition, the focus is “the point where light rays originating from a point on the object converge”.

An area of your image needs to be in focus. Perhaps you were to capture a tree. To gain a sharp focus, the light rays from that dot need to hit as few pixels as possible on your digital sensor.

When it comes to your image, there are areas in focus and areas out-of-focus. If you see sharp edges on an object, the object can be said to be in focus.

Focusing happens within the lens. This happens by moving one or more lens elements closer to or farther away from your camera’s imaging sensor.

The lens ‘bends’ the light and forces it to converge at different distances from the sensor.

The ideal convergence needs to fall exactly on your imaging chip. When you achieve that, you have a perfectly focused image or subject.

A diagram explaining the process of focusing your camera lens


Autofocusing is just one way to gain a sharp focus. With this mode, the camera sends a signal to the lens, forcing it to change its focal placement. How much of your scene is in focus falls on three different things.

Your aperture setting, the distance between you and the elements in the scene, and their spacial relationship.

What is placed in focus is down to where you set your camera to look. Many modern cameras have tens of focus points spread over your viewfinder.

They can be moved or even work in groups to select a more progressive focus blanket.

A flowchart explaining the autofocus process - camera lenses


Apart from leaving the focusing to the camera, which it’s pretty good at doing, there is the manual focus option.

This can be a better option depending on what you are photographing.

If you’re capturing a subject that is on the same focal plane, that is to say, not moving closer or farther away from you, refocusing is a waste of time.

Your camera might have trouble autofocusing in other situations too, like very low contrast or low light scenes. Shooting through glass is a great example of autofocus issues.

Some cameras are better at manual focusing than others. Rangefinders have a great way of focusing.

This is done by superimposing a ghost image over your viewfinder scene. They come together when an object is correctly focused.

Other, older cameras had a focusing screen that helped the manual focus. Modern cameras, such as the Lumix GH5, places a red halo around objects when they are in focus.

DSLRs let you focus in live view mode, which is magnifiable, making it easier to focus on far-away subjects.

Using Autofocus with Manual

Many lenses have a special feature, allowing you to autofocus the camera, then tweak the result manually.

Some lenses will not let you manually adjust the focus when in autofocus mode.

If you would like to test if your lens supports these manual adjustments, follow our steps.

First, set your lens to manual mode. Turn it back and forth to get a feel for the resistance.

Now set it to autofocus, and gently turn the focusing ring. If you feel more resistance than the manual mode, or hear any crunching sounds – stop.

A portrait of a female model in glasses with a blurry bokeh background - camera lens guide

Internal and External Focusing

There are two different types of focusing; internal and external. You will know if you have external focusing since the front element of the lens will extend when you focus.

This is handy to know for filters, especially polarising filters. If your lens turns when focusing, you’ll need to focus before setting your filters to their desired effect.

Distance Indicators

Lenses, especially those for film and analog, have built-in distance indicators. These are for the purpose of focusing, especially when you need to focus to infinity.

They aren’t exactly precise. But they are a good guide for knowing which way to turn the lens to focus at a particular distance.

Depth of Field Indicators

The lenses that have distance indicators usually have Depth of Field indicators too. These are marked as ‘22’, ‘11’ and ‘8’.

The numbers may differ, depending on the lens, its design, and properties.

What these markings designate is how much of your scene will be in focus at a particular aperture.

When capturing at f/22, with your focus set to infinity, you’ll see that everything from 3 meters onwards is in focus.

A Micro-Nikkor camera lens

Lens Mounts

Your lens connects to your camera body via lens mounts. There are two main types of mounts; screw and bayonet fitting.

The former is very rarely used in these days, yet you may encounter them with film and analog lenses.

The benefits of bayonet fittings allow lenses to change much faster. They secure on the camera body in a much safer way.

The most important aspect of these mounts is they allow for electronic connections between the camera and lens.

This is what allows autofocusing and electronic control of the aperture.

Canon uses EF or EF-S bayonet lenses. EF lenses can be used on EF-S cameras, but not vice versa. This is due to the EF-S lenses designed for smaller sensors.

Each camera manufacturer has their own lens mounts. This is with the exception of the Four-Thirds mount, which is backed and used by several manufacturers.

It is possible to buy and use adapters so that lenses from one manufacturer can be used on other manufacturer’s camera bodies.

This is especially true for all cameras with smaller sensor sizes, as it’s easier to adapt any lens mount.

A camera lens in the foreground of a blurry dslr camera body - a guide to camera lenses

Third-Party Lenses

Canon lenses can not be used on Nikon bodies, and vice versa. This means you’re stuck buying from the same manufacturer.

There are quite a few third-party manufacturers that create lenses for all top camera body manufacturers. Sigma, Tokina, Zeiss, and Tamron all create lenses for an array of lenses.

You may think these lenses don’t hold water to the Canon and Nikon counterparts. Some of these lenses are found to rival or better the largest DSLR manufacturers.

If your budget is tight, opting for a third party manufacturer is a great option. My Sigma 85 mm f/1.4 is half the price of the Canon version, and the sharpness is unparalleled.

Image Stabilization

Many modern camera lenses have built-in image stabilization. This feature allows you to capture scenes handheld that was previously challenging.

This technology utilizes the latest gyroscopic sensors and motors to stabilize any movement in the lens elements. Camera shake is a thing of the past.

Telephoto lenses are the ones that feature image stabilization. This is because longer focal lengths suffer worse from camera shake than from shaky hands.

The rule is to shoot at a shutter speed no lower than your focal length. A 50 mm lens has a limit of 1/60th of a second, and a 300 mm lens has a 1/250-1/300 range. IM allows you to bring this setting down to something more friendly.

Some cameras, such as the Canon R mirrorless have image stabilization built-into the camera. This turns every one of your lenses into a stabilized eye.

What to Consider

Image stabilization is a wondrous technology. But, not all vibrations are reduced by this feature. There is a limit to how far this floating lens element can move.

On top of this, camera movements that you’d like to keep might be removed. For example, panning shots wouldn’t work so well.

Image stabilization is quite power hungry. Your batteries might not last as long as they would normally. Turn it off when not using it.

A person holding a DSLR camera - camera lens guide

How Do Crop Sensors Affect Lenses

The film plane in 35 mm film cameras came in one size. This 24 x 36 mm hole allowed the film to be exposed correctly. Nowadays, with modern digital cameras, these sensor sizes have quite a range.

The Leica S2 SLR has a huge 30 x 45 mm sensor. Whereas the Sony RX 100 only has a 1” sensor measuring at 13.2 x 8.8 mm.

Here, we will be talking about how the size of the camera’s sensor affects the cropping of your scene.

Crop Factor

You may hear the terms full-frame, 35 equivalent, APS-C or cropped sensor thrown around. The big difference is what you are actually capturing from your scene.

A full-frame or 35 mm equivalent is the same thing. If a camera is listed as being full frame, it means it has the same size sensor as 35 mm analog cameras have: 36 x 24 mm.

APS-C, Four-Thirds and 1” sensors are all cropped when compared to a full frame sensor

  • APS-C (Except Canon) has a size of 25.1×16.7 mm. To get to 36 x 24 mm, you need to multiply the number by 1.5. This gives APS-C a crop factor of 1.5x.
  • APS-C (Canon) has a size of 22.5×15 mm. To get to 36 x 24 mm, you need to multiply the number by 1.6. This gives APS-C a crop factor of 1.6x.
  • Four-Thirds has a sensor size of 18 mm × 13.5 mm. To get to 36 x 24 mm, you need to multiply the number by 2. This gives four-thirds systems a crop factor of 2x.

The way a crop sensor works is that it magnifies the focal length of the lens. A 35 mm lens becomes 50 mm with a Nikon 1.5x crop factor.

A four-thirds camera with a 70-200 mm zoom lens would become equivalent to a 140-400 mm lens.

The general idea behind these different sizes is cost. Not everyone needs, or can afford a full frame sensor.

Camera manufacturers have created a range of sensor sizes to suit all budgets.

A diagram showing the difference between 2.0 crop factor, 1.6 crop factor, 1.5 crop factor and 35mm full frame


Most lenses have a filter thread in the front bezel. This allows you to screw in a filter. The filters cover a range of different ideas, including adding tints or darkening a scene.

Filter Threads

Every threaded filter has a different size, so it is crucial to choose the right size. On the filter, you’ll see the size of the threading that will look something like Ø=68 mm.

The big benefit here is you can use these filters as lens protection. Many photographers add a skylight or UV filter at the front. This stops any scratches, paint, dirt or bumps affecting the front lens element.

A filter is much cheaper and easier to fix or replace than a lens. These filters will add a little image quality degradation, but the alternative doesn’t add the peace of mind this solution proposes.

You could always take away the filter when photographing cityscapes or shooting towards direct light.

Drop-in Filters

Drop-in filters or square filters are a type of filter that fits into a holder. The holder screws into the lens’ bezel at the front.

The benefit here is that each filter you use doesn’t have to be screwed into the lens. This is a cheaper option, and easier to use than filter threads.

These are of higher quality and more versatile.

Rear Filters

Some lenses do not accept filters at the front of the lens. This is especially true for specialty lenses, such as extreme wide angle/fisheye lenses.

The front of these lenses is rounded, which leaves no space for a traditional, front filter. Some of these lenses have a slot at the rear of the lens where a filter can be added.

A close up of a hand holding a lens filter in front of a majestic landscape

Lens Hoods

I rarely see photographers using lens hoods. It could be a coffee cup sleeve if you don’t fancy replacing the one you lost. You might just see an improvement in your images. consider the following.

When direct sunlight hits your lens, it creates ‘flares‘ or ‘hot spots’. The sun could be hitting at an angle, because, god forbid, you photograph the sun straight on.

The lens hood stops the ambient direct light from ruining your images.

Something like this is very difficult to control when you use a wide angle lens with an 84° field of view. Some lenses, like the Rokinon14mm F2.8 Ultra Wide Lens, have the lens hood already built in. 

Which is great if you are prone to dropping things. My Rokinon fell from waist height and broke a part of the lens hood off. Thankfully, it protected the curved lens, bringing me to my second point – protection.

It is better to break something that costs $20 to save something that costs over $300.

Two camera lenses with lens hoods


We briefly looked at using third-party lenses on a different camera manufacturer’s camera body. This is possible through the use of an adapter that sits between the camera body and lens.

Teleconverters work in the same way. They modify the behavior of the lens you are using.

These secondary lenses sit between a camera body and a lens. They have an optical element within them, which refocuses the light.

Why is this useful? By refocusing the light, they effectively extend the range of your focal length.

There are different teleconverters at different strengths, but the most common are 1.4x and 2x. A 1.4x teleconverter on your Canon 70-200 mm f/2.8L lens would give you an effective focal length of 98-280 mm. Even further with the 2.0x.

The benefit is you can turn your telephoto lens into a super telephoto lens for a fraction of the cost.

The downside is, you lose some light, as the aperture minimum also increases at the same ratio. The f/2.8 becomes f/4 and f/5.6 respectively.

For more information on equivalence, see our What Is Equivalence in Photography? article.

1.4x and 2x. A 1.4x teleconverter for a Canon 70-200 mm f/2.8L lens

Getting Up-Close and Personal

Every lens has a minimum focus distance. What this means is, you can only place your lens at a certain distance to your subject before you can no longer focus. The Canon 100 mm macro lens can focus as close as 30 cm.

This may not sound close, but there are two things to take into account. The lens has a focal length of 100 mm, meaning you have a 20° field of view and can’t get closer to your subject anyway.

The second thing is that 30 cm is pretty good in comparison. The Canon 135 mm has a minimum focusing distance of 90 cm, three times further away.

Using macro lenses are just one way you can get closer to your subject. There are three other ways you can capture small objects at a ration of 1:1 and closer.

Close-up Lenses

A close-up lens (also known as a close-up filter or macro-filter) is another way you can get close to your subjects. This secondary lens enables you to capture macro shots without the need for a specialty lens.

Close-up lenses work the same way as reading glasses. They allow the lens to focus more closely that it would normally. These are easy to use, just screw on the thread at the front of the lens and away you go.

The benefit here is that you can stack them and use multiple filters together. A +1, +2 and +4 will give you +7 steps of closeness. Some single-element close-up lenses can cause challenges, such as severe aberrations.

Achromatic doublets are capable of producing great images with a small loss of sharpness. The Hoya 46mm Close-up Multi-Coated Filter Set is a good place to start. 

Extension Tubes

Macro extension tubes are lens spacers. They don’t have optical elements inside them like the teleconverters do, which means they are a cheap option.

They normally come in three different sizes, 7 mm, 14 mm and 28 mm.

The biggest benefit with these is that you can stack them together. 7 mm + 14 mm + 28 mm = 49 mm extension spacer.

Extension tubes work by reducing the focusing range of the lens you are using. Here, you can bring your subjects much closer to your camera. However, you lose the possibility of focusing to infinity.

You can make them yourself if you don’t have the budget for purchasing them yourself. For further reading, macro extension tubes work well with a process called focus stacking.

The Kenko Auto Extension Tube Set is a great extension tube kit to use. 

Kenko Auto Extension Tube Set

Reversing Your Lens

The other cost-effective option is to reverse a lens you already own. This might be strange, but it works well. Literally, take the lens off the camera and turn it around so the front lens element is facing the inside of your camera.

You’ll be able to focus on items very closely. This is best used with a tripod as you’ll need one hand to hold the lens and another to change the distance of the camera and tripod.

There are lens reversing rings, allowing you to connect your camera mount to your reversed lens.

This process works as a normally used lens focuses light from far away. Here, the image is much smaller. By reversing the lens, the opposite occurs.

The lens magnifies what it sees, giving near life-size reproduction.

a diagram showing how to reverse a lens for macro photography

Aberrations & Distortions

Lenses are never perfect. They all make a compromise between weight, versatility, size, focusing, and cost, among many other things.

Due to these compromises, the lens can suffer due to challenges it wasn’t made to encounter.


When light travels through a lens, it hits and bends when encountering the glass inside. Not all light bends the same way. Some colors are affected more than others.

They could be down to minor imperfections, diffractions or refractions of the light.

There are a few different aberrations you need to be aware of. they fit into two concepts; those that work with color (chromatic aberrations) and those that work with single points of light (monochromatic aberrations).

This area needs its own article. A Guide to Types of Lens Aberrations in Photography is what you’re looking for.

A diagram showing a lens with spherical aberration


Every lens has a varying degree of distortion. Generally, you’ll find smaller amounts of distortion when using prime lenses. This is down to fewer elements needed for the lens to work.

Constantly improving technology helps keep distortions to a minimal, especially with newer, more modern zoom lenses.

There are two main types of distortions. Barrel distortion makes the center of the image appear closer than the edges. Pincushion distortion makes the center appear much further away than the edges do.

Wide-angle lenses are plagues with distortion as their wide field of view needs to fit on a small, rectangle surface. It’s like trying to squeeze a fat cat through a relatively small cat flap; the edges need to squash.

you’ll notice the center seems unaffected. But, expect straight lines to curve as you extend to the edges of the frame.

And if you have a mixture of the two aforementioned, you’ll end up with mustache distortion.

For more information on what they are, what causes them, read our What Is Lens Distortion? You might also enjoy our How To Correct Lens Distortion in Lightroom: Step-By-Step Guide too.

Atmospheric monotone portrait of a man taking from a low angle


Sharpness is the great bane of annoyance to photographers. It’s easy to capture something you think is in focus.

It might even look to be the case on the small LCD screen on your camera. Getting home to check on a larger screen can have us gritting our teeth.

Centre Vs. Edges

The sharpness of your images comes down to how good your lens is, and *ahem* how good you are at focusing. For optimal sharpness in your images, you need to know how to use your lens properly.

When we do talk about sharpness, we measure it in a whole bunch of ways. Lenses tend to be sharper in the center. The edges and corners are furthest away from the sensor and can, therefore, suffer some loss.

Zoom Range

One of the biggest problems with variable focal length or zoom lenses is its sharpness range. A zoom lens has to make a compromise between many features, so versatility pushes the sharpness from the top spot.

It isn’t always clear where the optimal sharpness lies. Some lenses are sharpest at the extremes of their range.

This shows that designers placed importance on sharpness when fully zoomed in or out.

Other lenses can be sharper around the center of the range. There are a few lenses whose sharpest areas come and go throughout the focal length range. To find out if your lens does this or not, you need to get used to reading MTF curves.

These scientific charts let you know the optimal sharpness areas of your lens. They can be handy but can take a while to understand how they work.

Aperture Range

The other big thing you need to understand is that a lens curve of sharpness changes with its aperture range. Shooting wide open, your lens is less sharp generally.

Go down a few stops and you’ll notice a huge difference.

After this peak, your lens becomes less and less sharp, but its a gradual change.

This is something I learned about a long time ago but never knew why. Every time I needed a wide aperture, I would go to the lens’ limit (f/1.4 for my 85mm Prime) and then add two stops down.

This brought me to f/2.8 for optimal sharpness.

When we talk about more less sharp, the comparisons are subtle and gradual. Going from f/2.8 to f/4 isn’t going to show you a huge amount of difference. Going from f/2.8 to f/16 will.

On top of this, the quality of your images isn’t just down to sharpness. You will achieve beautiful images even when using the zoom lens’ least sharp aperture or focal length.

MTF chart for Sigma 85 mm f/1.4 lens
MTF chart for Sigma 85 mm f/1.4 lens

Specialty Lenses

Apart from zooms or prime lenses, even stepping out of the wide-angle, standard or telephoto lens realm, there are other lenses we need to talk about.

These specialty lenses have been created for specific reasons.

You’ll notice that these lenses might act similar to the ones we have already looked at, but have very unique qualities. Let’s touch on them briefly.

Tilt-Shift Lenses

A tilt-shift lens is a lens created to mimic the possibilities a large format camera gave us.

If you ever tried to photograph a building, only to see it fall away from you towards the top, these lenses are what you need to fix it.

This feeling is created because the large building is at increasingly different distances away from your camera. The top is farther away from you than the bottom is. A parallax error is created.

What these lenses let you do is change the focal plane to match the relative distance of the building from the camera. This change from a perpendicular focal plane to a parallel one fixes the problem.

The Canon TS-E 24mm f/3.5L is a great choice. If you’re looking for more information, read our What Is a Tilt-Shift Lens and How to Use One article. 

A triptych diagram explaining how a tilt shift lens works from different angles

Fisheye Lenses

Fisheye lenses are ultra-wide angle lenses. They fall into the focal length category of anything below and including 14 mm.

These lenses create a very unusual perspective in photography, usually resulting in a circular image.

When we use lenses that cause barrel distortion, we try to correct them to create a more realistic image. We embrace the distortion and use them to create something creative.

A fisheye portrait of a street food vendor at night

Macro Lenses

Macro lenses are specific glassware that allows you to capture small subjects and blow them up to bigger-than-life size.

These lenses are more commonly used for scientific or medical purposes but also used in nature and wildlife fields.

A macro photo of a butterfly on a yellow flower - camera lenses facts


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