014 - Fundamentals of Photography: Lenses
Have you ever wondered why some lenses cost way more than others? Have you ever wondered if it was worth paying that extra price for a lens that doesn't zoom at all? Have you ever just wanted to know more about how lenses work?
Then this is your episode! Because this week we are talking all about lenses and how they work. At the end of this episode, you should understand the differences between many lenses and how they impact the photography you want to do.
Invest in good quality glass before buying a new camera.
That’s the prevailing thought for most photographers, because, while a camera can make somewhat of a difference, upgrading your standard lens to a high-end lens will drastically improve your images and your ability to take photos (when compared to a quality difference of changing from camera body to camera body).
The lens you choose to use will change how you can craft a photograph. And you need to know what type of lens you will need for the photos that you will want to capture on your next big adventure. Because you can’t carry your whole kit while exploring (and you don’t really want to). So let’s get to know lenses and how they can change the photos you take, and let’s make sure you aren’t carrying around extra gear on your next trip.
So what are lenses?
In technical terms, photographic lenses are the optical objects that, when used in conjunction with a camera, allow us to create photographs. Lenses can be fixed to the camera, interchangeable, and of a variety of focal lengths and apertures.
Basically, the lens is the piece in front of the camera sensor that light passes through to create an image.
Now your lens choice determines 4 crucial factors.
Firstly, the focal range you can shoot at. Or, how much of the scene in front of you you can see in the camera.
Secondly, your available apertures (which affect things like depth of field and light hitting your sensor) see episode 12 for more!
Thirdly, the compression in an image. Or how close together everything looks.
Fourthly, distortions. Every lens has some level of distortion to it. In some lenses, this is intentional distortion (like on a fisheye lens). In others, we can correct a field of view by almost tilting the world in the lens to correct some distortions with a tilt-shift lens.
So, those four factors are going to determine a lot about the image you can produce. Will it have a creamy background? Will you utilize the distortions to craft an image? Do you need to see a lot of the image, or do you need to isolate a subject? All of this is determined by the lens itself.
Prime vs Zoom
Lenses come in fixed focal length (known as Prime Lenses) and zoom varieties. The difference between these two is pretty straight forward. Prime lenses have fixed focal lengths. Zoom lenses have a variable focal length. Meaning they can move between focal lengths.
There are strengths and weaknesses of each type. And which you use will once again depend on what you are shooting and on how you shoot.
Prime Lenses
Strengths: typically much sharper than their zoom equivalents, offer lower f-stops, and are simpler to build.
Weaknesses: lack of versatility and relative cost.
Zoom Lenses
Strengths: incredibly versatile, offering you a range of compositional and other elements due to their variable nature. They give you the ability to have multiple prime lens lengths in one lens, and due to this, require less switching of lenses. And are relatively cost-effective.
Weaknesses: they aren’t as sharp as prime lenses are, don’t offer the same level of low f-stops, and can be quite heavy.
So which is better? Zoom or Prime? That will depend entirely on what you need and how you shoot. Prime’s make for beautiful lenses for portraits, wildlife (being that most super telephotos are also primes), and anything where you can more easily use your feet to zoom in or out. A zoom lens offers that fantastic versatility that is so helpful when exploring a city, and you want to be able to capture vast cityscapes as well as close details. They also reduce the amount of kit you need to carry with you, giving you more room to pack other things.
6 Different Types of Lenses
Lenses come in a variety of different types. We are going to talk about 6 of them. In reality, there are many more, but these six are the most common varieties.
They are:
Wide-angle
Standard
Telephoto
Super telephoto
Macro
Tilt-shift
Something to note before we describe what each of these lens types does. You can get prime or zoom versions of nearly all of these lenses. You can also get lenses that go through these ranges. So, you can get one zoom lens that goes from a wide-angle view to a telephoto view.
Wide-Angle Lenses
These lenses cover the 35mm focal length and down ward.
Wide-angle lenses allow you to see a large field of view. They are much closer to what the human eye sees. As the name suggests, the view is wide. Beyond how much you can fit in the frame, wide-angle lenses can also be used to exaggerate distances between objects and to exaggerate objects themselves to make them look way bigger in the frame.
These are commonly used for landscape, architectural, cityscape, and astrophotography.
Standard Lenses
These tend to cover the 35mm to 95mm focal lengths. Although a lot of the zoom versions of these lenses will range slightly into wide-angle and slightly into telephoto (like the 24-105 that nearly every company produces as a standard, high-quality walk around lens).
Standard lenses are the middle ground between a wide-angle and a telephoto. These are the type of lenses you will commonly get with your camera as a kit lens.
The standard prime lens is typically considered to be the 50mm prime, also known as the nifty fifty. This is a lens pretty much everyone needs in their kit.
They are most commonly used for portraiture and as walk-around lenses.
Telephoto Lenses
These tend to cover the 100 to 400mm focal lengths.
Telephoto lenses are used for getting closer to subjects and for appearing to compress distances together.
Telephoto lenses are commonly used in event photography, sports photography, as well as some wildlife, depending on the length of the lens. They can also be used to create very distinctive and beautiful portraits. As well as fascinating landscapes. You don’t get the sweeping view you do with a wide-angle, but you get to see the scene in a whole new way.
One of the most common telephoto zooms is the 70-200 lens that is essentially a standard in the kit of wedding photographers.
Super Telephoto
Super telephoto lenses are the massive lenses you see at sporting events and you see wildlife photographers using. They cover the 400mm and up focal lengths.
These lenses are big and bulky, and very expensive and tend to be used for particular purposes. They also have a massive minimum focusing distance that requires you to be quite the distance from your subject before your camera even focuses.
Mostly you would use these lenses to shoot sports and wildlife. Things where you have to be a long way away from your subject to get photos of it.
Macro lenses
Macro lenses exaggerate small objects. They uncover detail impossible to detect by the eye and give a new perspective to extremely minute subjects such as insects or the petals of a little flower.
Macro lenses can be a bit confusing when you are just looking at their focal lengths, as they range from about 35mm to 180mm. They are designed to allow close-focusing to your subject and to give small objects a 1:1 size ratio or even 2:1 ratio, making small everyday objects appear larger than life.
Macro lenses are most commonly used for taking photos of plants, insects, and textures.
Tilt-shift lenses
These are worth mentioning here because of their unique properties.
Tilt-shift lenses allow you to control your perspective and plane of focus to capture distortion-free architectural and landscape photos. It is a lens all about perspectives.
Tilt-shift lenses allow you to correct vertical converging lines, which enables you to fix angled lines on buildings. You can adjust the tilting you see in buildings in your travel photos by using one of these lenses because it allows you to straighten out the converging lines. For this reason, they are often used for architectural photography.
Tilt-shifts also allow for the miniaturization effect you see in some photos. Where you can turn a real-world scene into something that looks like it was shot with life-like toys.
Tilt-shift lenses are amazing creative devices that have a multitude of uses.
How do Lenses Work?
In basic terms, a photographic lens is comprised of various optical elements that sit along a common axis. These elements allow light through to the sensor and work together to allow for your focal length, correct for aberrations and light flare, ensure proper aperture and allow for focusing, zooming, and stabilization (on lenses that zoom or are equipped with image stabilization). All this is housed within a metal or plastic body that then attaches to the lens mount on your camera.
What are Lens Elements?
The elements are the guts of a photographic lens.
Each complete photographic lens is made from a wide number of elements, and this depends on the lens’ construction and intended use. Elements are arranged along a common axis, meaning in a straight line with each other, and can be constructed of a single optical lens or multiple optical lenses held together. In the way we are talking here, optical lenses are the lens element inside a photographic lens. So basically, when we are talking about elements, the lens is the piece of glass (or sometimes plastic) inside a photographic lens.
This is where we get one of our first significant differences between a standard quality lens and a high-quality lens. Most standard lenses use plastics or lower quality refractive objects to craft their optical elements. Whereas most high-quality lenses use glass and high-end plastics to create their optical elements. This means better overall image quality because the material that light is passing through and refracting off of is of a higher standard. This also gets into why you are paying more for some lenses. Because of the way an optical lens is constructed, there will be distortions and aberrations in it. So lens designers need to correct for these aberrations, and they do that by adding different types of elements. Higher quality lenses will more correctly correct for these problems, whereas some low-quality lenses will not. This means that you are more likely to run into common lens problems (like vignetting, which is that darkening around the edges of an image or chromatic aberration, which is the purple or green haze you see on the edges of objects in some photos) with a low-quality lens.
Whereas a properly constructed high-quality lens will more properly correct for any of these problems. Essentially, the elements are made from better materials that have fewer aberrations in them, and they are built to a higher standard.
So that’s elements. And they are one of the big things you are paying for when you get a high-quality lens versus a standard quality lens. You are paying for a better material that the light is passing through (which directly impacts your image quality), and you are paying for a lens with better correction for aberrations (again, leading to better image quality).
Aperture
The role of the aperture is to control the amount of light passing through the lens to the sensor. A device called a diaphragm usually controls the aperture within a lens. It functions similar to an iris of the eye, where it controls the effective diameter of the lens opening. Essentially, the diaphragm gets bigger and smaller depending on how much light you want to hit your sensor.
As we spoke about in episode 12 on the Exposure Triangle, the aperture is responsible for not only how much light reaches the sensor (by making the hole on the diaphragm bigger or smaller) but also your depth of field (i.e., how much of your image appears to be in focus.)
The aperture within your lens determines which f-stops you have available to you to shoot with. This is again something you are paying for in a lens.
Some higher quality lenses offer the ability to get very wide apertures. Like f/1.2. Whereas most standard lenses will only go to f/3.5 or more typically f/5.6. You are paying for that ability to get more light into your camera and to throw more of the background out of focus.
Lenses can also have different types of apertures depending on their construction. Prime lenses have one maximum aperture, it doesn’t change because the lens doesn’t zoom.
In zoom lenses, however, there are two types of apertures: constant and variable. Constant apertures function like a prime, they stay the same no matter what zoom you are using. Variable apertures have different maximum apertures across their zoom range. You see this particularly in large zooms and cheaper lenses. This means that your maximum aperture changes depending on the focal length you are using. So your aperture maximum will vary between when you are at your shortest focal length to when you are at your longest.
Again, this is something you are paying for, particularly in zoom lenses.
It is more costly to construct constant aperture lenses across wide zoom ranges. But, depending on your type of photography, this constant aperture can be very worthwhile. Especially when you need to get more light into your camera. And when you don’t want to have to think about changing your exposure as you zoom in and out.
Focusing
How your camera focuses is determined by a couple of factors, one of which is the focusing ability of your lens itself.
Focus comes in two types on lenses. Manual and automatic.
Manual focus means you need to focus the lens yourself.
Automatic focus means the camera and lens together can focus for you.
For automatic focus, most lenses today use ultrasonic motors to move internal elements in the lens itself to create focus.
This is, again, one of the main things you are paying for in a lens. On a higher-quality lens, you are typically going to get more accurate focus results (meaning more photographs with the correct focus) and a lens that focuses faster. On lower quality lenses, you will get slower focusing and more regular times where you have missed focus. This is becoming less of an issue as cameras get better, but it is still an issue.
Lens Compression
Have you ever wondered why sometimes elements in a photo look all squished together like they are stacked on top of one another, and in other photos, they are seemingly impossibly far apart? That comes down to lens compression.
Lens compression is a type of distortion, one that is caused by the type of lens you choose to use.
Let’s start with a wide-angle lens. To fill the frame with a subject when using a wide-angle lens you have to get very close to the subject, so objects that are closer to you will appear far larger than objects that are further away from you.
This is one of the reasons why wide-angle lenses are not really flattering for shooting portraits. Parts of the person’s face will look a lot larger than usual, while other parts are farther away will look a lot smaller. You are distorting parts of this person’s face.
As you use longer and longer focal lengths, you are required to get further and further away from your subject in order to keep them about the same size in your frame. So, with a wide-angle, you may only be a few inches away from a person’s face where with a medium telephoto, you may be 1.5 meters away from them.
With each step up in focal length, our distance from the lens to the subject becomes proportionally more significant than the distance from the subject to the background. Let’s say that again, as we move further away from our subject due to the longer focal length, our distance to the subject changes. But their distance to the background does not. We get further from them, they don’t move.
This creates a sort of “flattening” effect, where the background appears closer to the subject and the objects in the background appear bigger. This change in distance to the subject is what actually gives rise to the “distortion” phenomenon.
A little bit confusing to think about, but you can change a lot about a photograph by changing your distance from a subject and using a telephoto to zoom in or by getting closer and using a wide-angle.
So, what are you paying for in a lens?
Primarily, it comes down to this.
With higher-end lenses, you are paying for better internals made from a higher quality material that should render better image quality. You are paying for faster and more accurate focusing systems. Sometimes you are just paying for that ability to autofocus, rather than buying a fully manual focus lens. You are paying for the ability to capture photos with a wider aperture and, sometimes, with an aperture that remains consistent throughout the zoom range. You are also paying for a lens that is better constructed and should last you for years. There are points where you are paying for a lens that will work with your camera. If you own a full-frame sensor, you will have to buy lenses that are built for full-frame, versus lenses that are built for APS-C sized sensors. Typically, full-frame lenses will cost more versus an APS-C sized lens.
That being said, do you need to go out and buy the big fancy high-quality lens? Not necessarily!
You need to think about the type of photography you are doing, and if buying the fancy version of that lens will really serve your photography. Because one massive walk-around lens (like the Tamron 18-270) may be perfect for you because you don’t want to carry more than one lens with you, and you want a lot of flexibility. You are ok with the less flexible aperture, seeing that it is a variable aperture, and at 270 the widest f-stop you can get is 6.3. It’s also very cost-effective and may make for a great one lens option for travel.
Or are you looking for the best of the best image quality and have the space and strength to carry around a few different lenses with you for a day? Then getting two or three lenses may suit your needs.
Maybe you only do portrait photography and need one high quality 85mm prime lens but want something for taking other photos in and around your city. A less expensive walk-around option may be best.
What this all says is you need to think seriously about the type of photography that you want to do and then look for lenses that work for that. But keep this in mind.
High-quality glass is an investment in your photography now and for the future. It will improve your image quality and will last you for years. If you have the money, and it will help with the type of photography you do, investing in high-quality glass is well worthwhile.