With such a broad array of camera lenses on the market, from so many different manufacturers, offering vastly different features, and all at wildly varying price points, it can be difficult to know just how to choose the best lens for your photography. This guide will explain camera lenses to help you evaluate what to look for when purchasing a new lens.
Camera Lenses Explained: An Introduction
What is focus-by-wire? What is the difference between a straight and a curved iris blade? When might you need to use optical image stabilization? Is a portrait lens the same as a telephoto lens? Why would you ever want to use focus limiting?
This in-depth guide to camera lenses explains in simple terms: how lenses work, what are the most common types of lenses, which are some of the most frequently seen features, and how and when you might want to make use of them.
What is a Camera Lens?
Before we go any further, let’s consider exactly what a camera lens is, and what we might want it to do for us.
In its most basic form, a camera lens is just a device for focusing light beams onto your camera’s image sensor. The barrel of a lens contains several precision shaped pieces of glass that serve to direct the light exactly where it’s needed. By using a focus ring or autofocus button to move these elements in relation to each other, you can be sure to capture a nice sharp image, whatever your distance is from the subject.
As simple as this task may seem though, it requires some clever optical engineering to get the image consistently sharp from corner to corner at all distances.
Of course, most modern camera lenses go a lot further than this. They often also employ various technical innovations in order to help you produce superior photos in virtually any shooting situation you could imagine. However, whether we’re talking about precision autofocus capabilities, sophisticated lens coatings, or any number of custom functions, it can be tricky to work out which of these features will make a genuine difference to your photography and which are instead just clever marketing spin.
What’s more, not all lenses are created equal in terms of their construction or the materials used. Some types of camera lenses are more appropriate for taking one kind of photo than they are for others.
To satisfy your photographic requirements, you’ll need to choose the right lens for the job. This means gaining a good understanding of what the different parts of a camera lens do, and how each of these parts can alter your photographs. It also means having a rough idea of what you might want to do with the lens in the first place.
How to Choose the Right Lens for Your Photographic Needs
In this guide, we will cover the main factors you will want to consider before committing to purchase a camera lens.
- Image Quality
- Focal Length
- Lens Mounts and 3rd Party Lenses
- Video Compatibility
- Size and Weight
- Lens Coatings
- Lens Hoods
Let’s take a look at each of these points in turn.
As a maker of images, image quality is likely one of your main concerns. Instead of saying “image quality,” we call it “photo quality,” because that’s the kind of images we’re making. It becomes obvious just how important image quality is to a photographer. Indeed, it can make the difference between a “good” and a “bad” photograph.
While the quality of a camera lens isn’t the only determinant of image quality, the contribution that a lens makes to image quality is nonetheless significant. More simply expressed, it doesn’t matter how good the sensor in your camera is if the image the lens projects onto the sensor sucks.
When we speak of the image quality of a lens, we’re really talking about the lens’s capacity to draw in light, bend and focus its beams, and then project those beams onto the sensor without any loss of accuracy. Loss of accuracy means light rays that do not realign properly when they hit the sensor, thus causing noticeable color aberrations, blurring, and loss of sharpness and detail.
Ensuring that a lens’s optics create a perfectly aligned image is no doubt a technologically impressive achievement. This can make the field of photographic optics sound extremely complex, and make the process of choosing a new camera lens seem like a terrifying experience.
However, although optical engineering is no doubt very important to us as photographers, we shouldn’t allow this fact to intimidate us too much. Camera manufacturers have been making lenses for many, many years, so they’ve had plenty of opportunities to become good at it.
While new functions are added from time to time, and certain features perfected, the science behind a camera lens remains relatively unchanged since the invention of photography over 180 years ago. Thus, while lens quality is massively important, the good news is that it’s actually quite difficult to find a bad quality lens today.
It is difficult, but not impossible. So yes, when shopping around for the right lens, pay attention to image quality. Make sure that any lens you are considering is free from optical errors (zoom in to files and look for softness or lack of detail, for double imaging, or strange color effects). Then stop worrying and go shoot, secure in the knowledge that few lenses today are terrible; indeed most are excellent.
The numerous types of camera lenses available are differentiated from each other by “focal length”, which is typically expressed in millimeters (mm); for example 28mm, 35mm, 50mm and so on. This measurement doesn’t refer to the physical length of the lens but is instead the distance from the camera’s sensor to the point where light rays converge to form an in-focus image of the subject inside the lens when it is focused at infinity.
Quite a mouthful, huh?
Thankfully, this rather technical sounding description is not something that we as photographers need to worry about too much either. Instead, focal length is important to us only as an indicator of the angle of view a particular lens will provide. For example: whether the scene that will be captured by the camera’s image sensor is wide, narrow, or somewhere in between.
Think of it as if you were trying to look at a mountain panorama while standing in a corridor. If you are standing way back in the corridor, your view will partially be blocked by the walls, so all you’ll be able to see is a very narrow segment of the mountains way off down the end of the hall. But move to the mouth of the corridor, and a much wider vista is revealed.
It’s the same with lenses: a sensor that is closer to the mouth of the “corridor,” in this case the lens barrel, will see more of the subject than one that is very far back. So a “long” lens, one with a focal distance of maybe 80mm or more, will show only a restricted view but will magnify this considerably when compared to the human eye. Meanwhile, a lens with a shorter focal length, 35mm, 24mm, and beyond, will provide a much wider view of the subject, but with a lesser degree of magnification; meaning that far-off elements will appear relatively small.
Between the two extremes of “long” and “wide,” we can find an angle of view that is closer to that which is seen by the naked human eye. A lens with a focal length of around 50mm being considered the most “neutral” and natural-looking lens for general use.
How Camera Format Affects Focal Length
The above discussion of focal length assumes that we are talking about the use of lenses on a camera with a full frame sensor, like one that has an image sensor the same size as a 35mm film negative: 36 x 24mm. If you have a professional-level camera, it will almost certainly come with a full-frame sensor.
However, most other cameras, whether these are entry-level DSLRs or Mirrorless cameras, contain smaller-sized sensors. These smaller formats are often referred to as “cropped” sensors.
Have you ever wondered why the round lens of a camera produces a rectangular image? The simple answer is that it doesn’t, but instead the rectangular format is dictated by the shape of the sensor. The sensor crops out the rounded “corners” to make a nice neat rectangle.
Exactly how much of the lens’s imaging circle is cropped out depends on the size of the sensor. The more of the image is excluded by the sensor, the narrower the angle of view becomes, like walking back into the corridor away from the mountains again. This means that although a 50mm lens used on a full frame camera may give a moderate “natural” angle of view, the same lens used on a camera with a smaller sensor will provide a much narrower view of the subject.
Therefore it’s important to note that, while some lenses intended for use on a full frame camera will also work on a cropped sensor model, in doing so the effective focal distance changes. For example, a Canon APS-C format DSLR has a magnification factor, also known as a “crop factor,” of 1.6. Meaning that when used with a 50mm lens, it will capture an image that looks like one produced by an 80mm (50 x 1.6) lens on a full frame camera. Meanwhile, Micro Four Thirds cameras have a crop factor of 2, so a 50mm lens will provide an angle of view that is equivalent to that of a 100mm lens on a full frame camera.
This doesn’t work in reverse though. A lens intended for use solely with cropped sensor cameras will not have a sufficiently large image circle to be used with full-frame cameras. Even if such a lens could theoretically be used, the image it produces would be smaller than the full frame sensor.
Aperture simply means “opening.” In photography, the term aperture specifically refers to the opening of the iris inside the lens and is expressed as a series of numbers, typically preceded by an f/.
For example, f/5.6 or f/13. You will see these numbers on your camera’s LCD, and possibly even marked on the barrel of the lens itself. These settings are commonly referred to as f-stops. Aperture numbers indicate how wide a lens iris will open, and consequently how much light will flood in and hit your camera’s image sensor.
Somewhat counterintuitively, a wide aperture, a big opening, is expressed as a lower f-stop number. For example, f/1.8 is very wide open, f/2 marginally less wide, f/2.8 slightly smaller still, and so on. The lens iris shuts down even smaller, which means it lets in less light, as the numbers rise through f/8, f/11, and on to f/16, and even f/32 or f/64 on some professional camera systems.
Although all lenses will allow you to work at a number of different aperture settings, the maximum and minimum aperture settings possible will vary between any given lens. For example, the cheaper kit lenses that come with entry-level DSLRs typically have a maximum aperture of around f/3.5 to f/5.6 whereas more expensive professional lenses may allow shooting at much wider apertures such as f/2 or f/1.4.
Fast vs. Slow Lenses
A wide opening, like f/2, is considered to be “fast” because it lets a lot of light in quickly. Conversely, a smaller opening is considered “slow.” Hence when people speak of a “fast lens,” they do not mean one that is quick to operate, but rather that it has a wide maximum aperture, like f/1.4 to f/2.8.
Fast lenses are often highly prized by photographers as they allow handheld, flash-free shooting even in dimly-lit situations. Unfortunately, they tend to cost a lot more money than slower lenses. For this reason, lens manufacturers will often offer a range of two or three lens models with otherwise quite similar specifications but differing maximum apertures. So if you’re wondering why two seemingly identical lenses have extremely different costs, the first place to look for an answer is at the maximum aperture.
How much more money you will need to pay in order to get a faster lens depends in part on its focal length. For example, mid focal length lenses, say between 35mm to 50mm, are relatively easy to manufacture with a fast maximum aperture, so these tend to retail at fairly moderate prices.
However, the further you move away from mid focal length lenses, the more you’ll have to spend in order to get a fast maximum aperture. Hence a 50mm f/1.8 is quite a common and relatively affordable lens, whereas an ultra wide or long telephoto lens with the same maximum aperture could be considered an expensive luxury, aimed more at the professional market.
While many photographers shun slow or variable-aperture lenses, there’s no point in paying out for faster aperture settings if you will not make use of them. Every photographer has their shooting style and different needs. If achieving a shallow depth of field or shooting with a fast shutter speed in low light aren’t high on your list of priorities, then by all means go for the cheaper variable-aperture lenses.
A lens iris is made up of a number of interlocking blades that shut down or open up according to the f-stop selected. The more blades a lens has, the more sides the hole will have, and therefore the closer this hole will be to a circular, rather than hexagonal, shape. What’s more, on some lenses the iris blades are quite straight, on others they are curved: straight blades will make for a more angular iris opening, curved blades a rounded one.
Although this may seem like an irrelevant technical detail, the number and type of iris blades a lens uses can be of some interest to us as photographers. They determine the way in which out of focus elements of an image will be rendered. This is often referred to using the word bokeh. More aperture blades tend to make for smoother bokeh, and more rounded blades make for more rounded pinpoints of light in the background of photos. Many people like this.
The out of focus rendering produced by different lenses can vary quite considerably, and some lenses produce much more attractive bokeh than others. However, quite how important this matter is to you is something you’ll have to decide for yourself: if all a photo has going for it is nice bokeh, it’s probably not a very interesting photo. It’s arguable that if people are paying too much attention to the way in which the background of your photos is rendered, you might want to make a little more effort with the foreground.
This is undoubtedly a minor consideration in comparison with critical details such as maximum aperture. Nonetheless, some photographers may also want to check the number and shape of aperture blades before putting down their hard-earned money on a particular lens.
Optical Image Stabilization
When it comes to holding the camera steady at slower shutter speeds, every photographer will have a different level of ability. Most of us can improve in this area with a little practice, perhaps getting down to 1/30 of a second or below on a short lens. However, there of course comes the point where even the most steady-handed of shooters will start to get blurred photos due to camera shake.
This is where a lens with image stabilization can come in very handy: optical image stabilization helps to produce blur-free images at even slower shutter speeds than your natural limit, potentially making a difference of a good 2 to 4 stops of extra light.
For example, camera shake is a particular risk when shooting with longer telephoto lenses. You might ordinarily struggle to handhold a longer lens at 1/90 of a second, but by using image stabilization, it’s possible that you could drop down to shutter speeds as low as 1/15 and beyond and still get a usable image without having to resort to a tripod.
Some manufacturers provide onboard image stabilization in camera bodies in the form of a sensor that moves to compensate for your shaky hands. Meanwhile, some lenses feature optical stabilization, which is instead a floating lens element that moves in the same way: and effectively provides the same result.
Some stabilization systems come with multiple settings. For example, one that restricts correction to vertical movements only: allowing you to smoothly follow a moving subject without the stabilizer trying to correct the horizontal pan motion.
Currently, in-body optical stabilization is only an option on certain cameras. If you use a system that doesn’t offer optical image stabilization within the camera body itself, in-lens stabilization is the only way to get it. Naturally IS lenses tend to cost more than their non-stabilized equivalents. Also, be aware that the extra juice required to power the image stabilization motors means that using this feature will tend to run down your camera’s batteries slightly faster than when using a regular lens.
Another way to help ensure that photos taken with a long lens remain blur-free is to purchase one that comes with a tripod mount. Also known as a tripod collar or tripod ring, a tripod mount permits you to attach a tripod or monopod directly to the lens itself, rather than to the camera body. This provides much greater support at the center of gravity and therefore stops the extremities of the lens shaking about.
Generally, a tripod mount will only be found on longer, heavier lenses were there is a serious risk of camera shake, even in ordinary well-lit shooting conditions. You would not expect to see a tripod mount on a 35mm “pancake” lens, for example, as it would be completely unnecessary with such a short focal length.
Just as a powerful jet will not fly if it has no wings, an aerodynamically designed airplane will not get off the ground if its engine cannot provide the necessary thrust. This is a roundabout way of saying that there are many different factors contributing to fast and accurate autofocus.
Some of these contributing elements are in the camera body, while others are in the lens. If your camera is reputed to have amazing AF capabilities, but you stick a substandard lens on the front of it, don’t be surprised if AF performance disappoints. Likewise, you may own a lens that is theoretically able to focus with lightning fast accuracy, but if it’s not coupled with a similarly high-specced body, it will never deliver to its maximum potential.
Be sure to check out the compatibility of lens and body regarding autofocus, as it would make little sense to pay out a premium for a top of the range lens if your camera is not advanced enough to make use of the lens’s sophisticated focusing capabilities to the full.
However, just how advanced any photographer needs their autofocus to be is debatable. For sure, nobody wants to see frame after frame ruined by inaccurate focusing. Or miss the shot entirely while their lens jerks back and forth – confused by tricky lighting right at the crucial moment.
But with the average entry-level camera doing a very good job of focusing most of the time, and the number of focus points on top-end cameras now reaching well into the hundreds, it may be that we’ve passed the point that future advances in this area will make a significant difference to user experience.
In any case, the majority of improvements we see in autofocus nowadays mainly lie in sensor technology rather than the lens itself, although clearly, the two need to be compatible to produce good results.
In short, yes, a lens that focuses quickly and accurately is important. But it’s not something that is especially difficult to find today, so don’t be fooled by marketing into purchasing something much more expensive and “advanced” than you really need.
What’s more, even the world’s best autofocus may still struggle in tricky lighting situations: whether this be caused by an insufficient level of light, high contrast back-lighting, or conversely by a total lack of contrast, as found for example in foggy or misty conditions. Either way, poor lighting may confuse the AF sensor, sending it jerking back and forth looking for something to focus on.
In such situations, manual focus may be the only way to get a sharp image. Furthermore, if you shoot video and wish to experiment with clever rack focus techniques, manual focus is pretty much the only way to go.
Most lenses come with a switch to choose between auto and manual focusing operation and, if not, this can usually be selected via the LCD or by using a button on the camera body itself. However, in reality, many modern lenses, particularly those for mirrorless systems, do not feature genuine manual focus, but instead an electronic simulation of manual focus.
In practice, this means that as you turn the focus ring on the lens barrel, you are not directly controlling the lens elements themselves, but instead, the elements are moved by a motor. This method of “manually” focusing is usually referred to as focus-by-wire.
Some people don’t like focus-by-wire systems, as they feel they provide less direct control of the camera. If you think you might make considerable use of manual focus operation, be sure to try out manual focus with your shortlisted lenses before purchasing. If you don’t find the manual focus ring satisfyingly responsive, keep looking.
Some lenses, particularly longer lenses, come with a focus limiting switch. This function permits you to restrict autofocus so that it can only operate within a certain predefined range of distance from the camera. For example, if your subject is far away and therefore you will only be focusing at a great distance, autofocus will be faster and more accurate if you can tell the camera not to waste time trying to focus on closer objects.
Focus limiting is particularly useful when there are various potentially distracting objects in the foreground that might confuse the camera: for example when following a person in a crowd, or photographing through foliage with a telephoto lens – as a paparazzi photographer might.
Some lenses even allow you to specify the precise focus range that a lens should be restricted to. Just remember to switch off focus limiting before moving on to another subject at a different distance; otherwise you may find that all subsequent photos are out of focus.
Lens Mounts and Third Party Lenses
Most camera brands have their own proprietary lens mounting system that is generally incompatible with products made by other manufacturers (some brands even have multiple lens mount systems, one for each of their different camera lines). So, for example, a Canon lens cannot be used on a Nikon body, and vice versa. Olympus and Panasonic Micro Four Thirds cameras are the one notable exception to this, as they can accept any Micro Four Thirds mount lens.
Meanwhile, there are numerous third-party manufacturers making lenses suitable to be used with many different brands using appropriate mounts and adapters. While third-party lenses were once seen as an inferior option, purchased only by those who could not afford lenses offered by the leading camera manufacturers, in recent years this has changed. Many third-party offerings now every bit as good as those made by Canon, Nikon, etc. while still potentially offering some savings.
With so many different options available, before purchasing a lens it’s essential to know precisely which type of lens mount your camera requires.
If you also plan on using your lens to shoot video, be sure to give some attention to video-specific considerations too. For example, a lens you’re thinking of purchasing might feature near-instantaneous autofocus, consistently produce tack-sharp images, and display very little in the way of color aberrations – all of which would make it a fantastic choice for producing stills. Despite this though, this same lens might be inappropriate for shooting video, perhaps due to a particularly noisy AF mechanism or an unresponsive manual focus ring.
Size and Weight
Better that you purchase a mediocre piece of budget glass that sees a lot of regular use than go for the world’s most optically perfect lens if in the end, it’s such a bulky deadweight that it just gets left at home all the time.
Just how important the size and weight of a lens will be for you depends on the type of photography you plan to do. Those who spend 8 hours a day wearing the soles of their shoes into the ground shooting street photography will probably want to go for either a compact all-purpose zoom or a couple of lightweight and pocketable primes. But if either studio photography or photographing landscapes from the parking lot are more your style: well sure, go for that armored tank of a lens, why not.
Similarly, how and where you plan on using a lens will dictate just how durable it needs to be. A lens that will spend much of its life sitting in a dust-proof studio lens cabinet only to be taken out for a calm portrait or still life session once in a while will likely survive for many years, no matter how cheap and fragile its construction. Meanwhile, if worn around the neck of a particularly active photojournalist, the same lens might last no more than a couple of hours before being violently swung into a door frame or shattered on a rocky ground.
Some lenses are of mostly metal construction and, if well-treated, will likely last a lifetime. Others are lightweight, plastic trash. They are little more than toys. Consider your needs vs. budget, and be prepared to pay out considerably more for a better-built lens.
Weather sealing too is an important consideration. Again, lenses that offer a degree of protection against, water, heat, cold, and dust, etc. will cost more. Just bear in mind that there’s probably not much point in paying out the extra premium to purchase a splash and dust proof lens if your camera body isn’t also weather-sealed to a similar degree.
It’s also worth noting that different manufacturers use different terms for weather sealing, and so it can sometimes be tricky to gain an accurate understanding of just how much protection against the elements a specific lens offers.
Many lens manufacturers play up the incredible advances in optical coatings that they have developed in their laboratories, often giving them impressive and futuristic sounding names. To be sure, these finishes can no doubt play a significant role in improving sharpness and minimizing glare, flare, reflections, color casts, and other chromatic aberrations.
The fact is, though, that most manufacturers have been applying anti-reflective coatings of this kind to their lenses for many decades. So, while undoubtedly an important part of lens technology, all modern lenses (post-1960s) come with some degree of anti-reflective coating.
In short, the fuss made by manufacturers over lens coatings is often more about marketing than anything else. Yes, you probably wouldn’t want to use an uncoated lens, but as all modern lenses have some coating, it would be challenging to find an uncoated lens today even if you wanted to.
While there are undoubtedly some slight differences in the coatings used by different manufacturers, and even between the different lens models offered by one manufacturer, the topic of lens coatings is not one worth getting too caught up in. Either the lens performs well optically, or it doesn’t, but don’t go purchasing a lens largely on the strength that it’s hyped as coming with some fancy new finish.
A multilayer coating of the kind used by most, if not all, major lens manufacturers today will reduce the risk of reflections to almost zero. Yes, an unfortunately placed reflection can potentially ruin a shot, but they are generally such a rare occurrence that we’d probably make better use of our energy worrying about more important things.
With that said, it doesn’t matter whether it’s a multi-coating, a nano-coating, or a mink-fur coating: no kind of coating will save you from lens flare if you point your camera directly into the sun.
Let’s go back to the corridor analogy from earlier. If you’re standing way back in the hallway, you won’t be able to see all the view beyond the end of it, just a narrow part of the view. However, if you are right up front, the sun might be shining directly in your eyes, stopping you from getting a good look at the scenery anyway. Thankfully, just taking a small step back can often be enough to block off the sun so that you can enjoy the view.
A lens hood works in the same manner, extending the lens barrel in such a way as to block unwanted light from shining down the lens and causing flare and reflections, yet without altering the focal length (because it’s placed after the lens elements).
Some lens hoods are made from metal, and others are made of plastic. Some lens hoods are compatible with the lens cap, and others will need to be removed before the lens can be put away. Some manufacturers provide a lens hood for free with the lens, and others do not. These are all points worth considering when comparing the cost of two different lenses.
Main Types of Camera Lens
Having discussed the most important technical features that go into making a good camera lens, we now turn our attention to each of the different types of camera lens available and their various uses.
As the name suggests, ultra wide-angle lenses provide a very wide angle of view, allowing you to capture much more information in the frame when compared with a shorter lens. This makes them ideal for shooting panoramic scenery, or when photographing in an enclosed space where there is no possibility to move further back from the subject (for example due to a wall).
Typically we’d consider any lens with a focal length beyond about 24mm to be an ultra wide. But beyond the simple angle of view, ultra-wide lenses also share specific distinctive characteristics. For one, they tend to produce images with a much greater depth of field than those shot using a shorter focal length lens. Indeed, it can often be difficult to achieve a shallow depth of field with an ultra-wide lens, even when shooting at the maximum aperture setting.
Frequently ultra wide lenses will also permit focusing on very nearby objects. However, ultra wides tend to suffer from a quite extreme perspective distortion, so that objects close to the lens appear very close (and therefore big in the frame), and those further away appear very far away (and therefore tiny in the frame). This can make them an extremely unflattering choice for taking portraits of people: unless you deliberately want to make your subject look like a bulbous-nosed freak, better to go for something shorter in focal length.
Another issue is that the vertical and horizontal lines of buildings etc. will often appear to converge when photographed with an ultra wide angle lens from any position other than squarely straight on (and often even then). Thankfully though, this problem is relatively easy to fix in the post-processing stage.
Of course, all of these perspective “errors” can also be used to creative advantage. So ultra wides are often used by photographers who shoot extreme sports or do band portraits for the dynamic and exaggerated point of view they create of the subject.
More generally though, ultra wides are used in landscape, architecture, and interiors photography; particularly by real estate photographers, who often need to provide a very wide and spacious-looking view of small spaces to help rent or sell the property.
Wide-angle lenses are those with a focal length that falls somewhere between 24 and 35mm. They typically have similar characteristics to ultra wides, just in a slightly less extreme form. This means that they not only capture a narrower field of view than ultra wides but also suffer a little less from problems of converging parallels and other forms of perspective distortion.
As with ultra wides, wide-angle lenses are valuable tools for capturing a wide view of a scene in a single frame. However, as they have a slightly less dominant “look” than ultra wides, they are much more useful for general day-to-day use. This makes them a good choice for landscapes, interiors, documentary, and street photography.
A moderate wide-angle lens can even be an interesting and creative choice for shooting portraits, especially when you want to include something of the environment in the frame along with the main subject. Once again though, getting too close to the subject of a portrait with a wide-angle lens will cause unflattering perspective distortion that your sitter may not thank you for.
Lenses that offer an angle of view and perspective that is closest to human vision are called standard lenses. Thus we tend to look upon images created using standard lenses as having a somewhat “natural” or “neutral” look to them. Typically a standard lens’s focal length is 50mm, sometimes 55mm, and very rarely 45mm (some might consider the latter to be a moderate wide angle lens).
Standard lenses suffer from much less risk of perspective distortion – such as converging parallels – and are therefore more flattering for shooting portraits than wide angle lenses. They are good all-purpose lenses for photographing a wide range of situations, from landscapes and events to travel and documentary.
Standard lenses tend to be cheap, small, lightweight, and have fast apertures, making them an ideal choice for a photographer’s everyday go-to lens (although many photographers prefer wide angle lenses for the more unusual point of view they offer).
While there’s no clear agreement as to what focal length constitutes a true telephoto lens, generally speaking, a telephoto lens can be considered to be any lens with a focal length that is longer than a standard lens. In practice, this means a lens longer than say 70mm. Telephotos also tend to be correspondingly larger in physical terms too: i.e., a longer focal length often also means a physically longer and heavier lens barrel.
The field of view provided by a telephoto lens is relatively narrow, and magnification of the subject is much greater than with wider lenses, effectively making far away subjects seem much closer to the camera. A side effect of this is that telephotos give the appearance of “flattening” the perspective of a scene, meaning that things that may in reality be many feet apart can appear to be situated very close together when photographed using a telephoto lens. The longer the focal length, the stronger this effect.
Photos that are taken with a telephoto lens generally have a much shallower depth of field than those made using a wider lens. Even when the diaphragm is stopped down to the minimum aperture, it can be almost impossible to get both background and foreground sharply focused in the same shot when using a longer telephoto.
In their most straightforward use, telephoto lenses are suitable for photographing far off subjects that, for one reason or another, you can’t get any closer too physically. This makes them ideal for sports, nature, and wildlife photography. A telephoto is also the archetypal paparazzo lens, used by celebrity and news photographers for secretly shooting subjects from a distance.
Beyond this though, the interesting perspective created by a telephoto lens means that they lend themselves well to more creative uses, particularly when you either wish to isolate a subject against a blurred background and foreground, or instead graphically flatten a scene.
Primes vs. Zooms
A prime lens is simply a lens offering a single focal length: say a 50mm standard lens or a 28mm wide-angle lens. Prime lenses do one job and generally, do them pretty well.
In contrast, zoom lenses permit the user to choose from a range of focal length settings: for example, from 28mm through to 70mm, and all settings in between. Zooms are convenient jacks-of-all-trades, but frequently masters of none.
As we mentioned in the introduction, a lens is designed to focus light beams onto the camera’s sensor, making sure that they are perfectly sharp across the entire image plane, even at the edges. Achieving this requires some precision engineering and the use of various moving parts to maintain consistent accuracy when focusing light at different distances. And that’s just with a fixed focal length prime lens.
A zoom lens is effectively many prime lenses in one, with lens elements shifting to provide accurate focusing at different focal settings. As you can imagine, this makes the internal workings of a zoom a great deal more complicated than those of a prime lens.
This extra degree of complexity adds bulk and weight to the lens, and of course, also makes a zoom more costly to manufacture. Indeed, owing to all the extra internal parts that are required to cover the breadth of optical settings offered by a zoom lens, typically zooms are significantly bigger and heavier than primes. So while zooms may provide a great deal more flexibility in terms of point of view, they rarely make for the most discrete, portable, or lightweight lens option.
What’s more, manufacturers usually have to compromise in some way to keep the weight, bulk, and the price of a zoom lens to a minimum (there’d be little point in producing an optically outstanding zoom lens if nobody could physically lift it, never mind afford to purchase it).
Usually, this compromise is made in one, or indeed both, of two areas.
First to be sacrificed is often maximum aperture: producing an iris capable of opening wide enough to let in a lot of light can be difficult and expensive when there are so many other moving parts crammed into the lens barrel. In practice then, you’ll often see zoom lenses with a moderately fast maximum aperture at wider focal lengths (say f/3.5 at 28mm), with this falling off significantly as you move through to longer zoom settings (say dropping to f/5.6 at 100mm).
So even if you set the aperture to f/3.5 at the widest focal length, the aperture will automatically close down to f/5.6 as you zoom in. Lens manufacturers typically indicate non-constant apertures on the front of the lens by writing the maximum aperture first, followed by the minimum; for example, f/3.5 – 5.6.
The other area in which zooms tend to take a noticeable hit when compared to primes is simply in image quality. Without getting too technical, all the extra glass and mechanics inside the lens make it more difficult to maintain uniform precision and accuracy. So sometimes a zoom lens may be extremely sharp at wider focal settings, but produce notably less crisp and defined images at longer focal lengths.
In the worst case scenario, image sharpness may be substandard at all settings when compared with a similarly specced prime lens. For the same reasons, zooms tend to be more prone to color aberrations, flare, and ghosting.
With that said, professional-level zoom lenses can often maintain a consistent maximum aperture throughout all settings, and may even be almost as sharp as primes. Needless to say though, such high-end zoom lenses are exceedingly expensive.
In short, primes may be less convenient than zooms, but they usually come with superior optics, faster apertures, and cost considerably less money. Of course, you don’t get as much flexibility out of primes. But what they do, they generally do very well.
If you care about image quality, you’ll likely go for a well-chosen selection of prime lenses. But if you put a higher value on convenience, a single zoom lens might cover all the bases. And depending on precisely which make and model of zoom we’re talking about, the degree of compromise may not be too serious in the end anyway. Or, at least, it may be primarily financial.
Indeed, as many photographers will value different criteria depending on the exact shooting situation and their particular needs, you’ll commonly see camera bags containing, say, a decent mid-range zoom for general shooting, and then a couple of precision primes for when quality, speed, and a shallow depth of field are more important than convenience.
You may sometimes see reference to “superzooms.” A superzoom lens is simply a zoom lens offering an enormous range of focal length settings – from very wide to very long. These are commonly found on entry-level Mirrorless cameras but are occasionally also available for other formats.
Superzooms can certainly make for useful all-purpose lenses, allowing you to shoot in pretty much any conceivable situation without the need to carry around more than one lens (handy on vacation, for example). They come with all the same drawbacks as regular zooms regarding image quality and maximum aperture, only magnified by several degrees. Naturally, there’s a high price to be paid for that extra level of convenience, so if you value image quality, you will probably do well to avoid superzooms entirely.
Other Types of Camera Lenses
Portrait lenses are those with a focal distance of something roughly between 70 and 130mm. I.e., they are short telephoto lenses that are well-suited to photographing just a subject’s head and shoulders at a flattering distance. They also tend to feature a relatively fast maximum aperture to create a shallow depth of field, thus helping to separate the subject from the background.
Beyond falling into this approximate focal range, there is nothing technically distinct about a portrait lens. Nor is there any reason why you shouldn’t use another type of lens to shoot portraits if you want to (see the comments above regarding ultra wide angle lenses). Rather, the term is simply used to refer to lenses that are considered particularly appropriate for classical portraiture. Those with attractive bokeh are especially valued.
Tilt/shift lenses were traditionally seen on old large format field cameras (you know, the ones where photographers had to put a black cloth over their head to take the photo). The flexible, concertina-like bellows between the lens and the back of the camera permitted the photographer to tilt or shift the angle of the lens in relation to the film plane, thus “correcting” the converging parallel lines caused by perspective distortion. This makes tilt/shift lenses invaluable for precision architectural and interiors photography, where leaning verticals or wonky horizontal lines are a big no-no.
Although today most tilt/shift lenses are made for digital cameras, they still work in the same way: by allowing the user to adjust the angle of the lens in relation to the image sensor.
Beyond altering perspective, the movement of the lens in this manner has the secondary effect of changing the plane of focus. On a regular lens, the focus plane is fixed: i.e., if I focus on a particular object 10 feet away from the camera, then all objects 10 feet away will be in focus too. But with a tilt/shift lens, this line of focus can be swiveled on its axis wherever the user wants.
For example, I might move the plane of focus so that it is no longer on a fixed distance arc around the camera, but is instead placed so that it runs diagonally from foreground to background at an angle of 45 degrees. Now any object that coincides with this diagonal plane will be sharply focused.
In the example I’ve just given, this would mean that any objects on the line of focus would be sharp, regardless as to whether they are in the background or foreground of the image. Meanwhile other objects in both the background and foreground – perhaps even ones just a few feet from the plane of focus – would be blurred.
If you’ve ever seen those videos where cities appear to be tiny models inhabited by fast-moving ants, these are made using a tilt/shift lens (or at least a video editing plugin that emulates one) to create a very narrow depth of field and a disturbing perspective.
Tilt/shift lenses are an essential piece of kit for professional architectural photographers, but for the rest of us their usefulness and appeal is likely to be quite limited. In any case, they tend to be very expensive.
A fisheye lens is merely an extreme form of ultra wide-angle lens, typically with a focal length of around 8 or 10mm, and often with the lens’s entire circle of view projected onto the camera sensor to create a round image. Sometimes used in security cameras to give a 180-degree view of a scene, the convex perspective distortion created by fisheye lenses is so dominant that it renders these lenses of limited use to the average photographer: arguably, if you’ve seen one fisheye photo you’ve seen them all.
Nonetheless, fisheye lenses were very popular with 1960s psychedelic bands, and some skate and snowboard photographers still shoot with them today for the exaggerated and dynamic look they create.
Technically, a macro lens is one that is capable of a reproduction ratio of 1:1 or greater. However, in common usage, the term is also frequently employed to refer to any lens that can be used for shooting extreme close-ups. Macro lenses come in a variety of focal lengths, however, they are most typically found within the range of about 80 to 110mm.
A macro lens may offer the same angle of view as a non-macro lens: e.g., 80mm, which is often also considered a good length for portraits (see above). What distinguishes the macro lens from a regular lens in the same focal length is the macro’s ability to focus on very near objects, thus magnifying them considerably.
For example, a regular 80mm lens will enlarge objects in the frame in the same way as a macro 80mm does, but it may not be able to focus close enough to completely fill the frame with a small subject, such as an insect for example. The necessity to step back from the subject to get it sharply in focus means that it will appear smaller in the frame than when photographed using a macro lens of the same focal length.
Macro lenses tend to be valued for photographing the natural world up close, for the precision copying of documents, in scientific and forensic photography, and also for many other more artistic uses. While macro lenses can focus extremely close, they are generally not restricted in how far away they can focus, meaning that they can also be used in a more normal manner if desired. Hence an 80mm macro lens will likely also double up as a good portrait lens.
A pancake lens is merely an extremely short, flat lens that extends no more than about an inch or so in front of the camera. While they are most typically made as prime lenses, some pancake zooms also exist. Pancake lenses tend to combine optimum image quality with a profile that in some cases can be so slim as to render a DSLR camera pocketable. Most pancake lenses offer either a wide-angle or standard field of view.
As we’ve seen above, camera lenses are technically sophisticated examples of optical engineering. And to a degree, the quality of our work as photographers depends on selecting the best lenses we can afford. All the same, if your priority is producing great photographs rather than geeking out on tech-spec, it’s important not to get too caught up in the technical side of lenses. They are essential tools that should be chosen carefully and treated with respect, but ultimately it’s what you do with them afterward that counts.
Hopefully, this guide has fully explained camera lenses and answered all your photo-optics questions, arming you with the necessary knowledge to select only those lenses offering the features you need for your photography. If you’re now considering purchasing a new lens, and have already committed to a particular camera system (or simply want to make a comparison between different brands), be sure to check out our series of brand-specific guides to the best lenses currently available from the most popular manufacturers.