One of the most important parts of your photography equipment is the lens – the zoom lens is just one of many options. But with so many options, how do you know which lens is right for you? In this article, I’ll explain what a zoom lens is and how it works. I’ll also tell you the types and advantages of zoom lenses and when you should use them.
What are zoom lenses?
A zoom lens allows you to quickly and easily recompose an image while remaining in the same physical position. A zoom lens is a lens whose focal length is not fixed but can be changed. To give you a better idea of what this means, I’ll briefly explain the concept of focal length.
Focal length – what is it actually?
The focal length is the value that determines the angle of view of the camera. It therefore determines how large the field of view of the shot is. The focal length is given in millimeters and usually ranges from 8 mm to 300+ mm. Of course, this doesn’t mean that your photo is just a crop of a few millimeters. Instead, the value refers to the distance between the lens and the sensor.
A focal length of 50 mm (on a full-frame camera) is about the same as the angle of view of the human eye. Therefore, with a 50 mm focal length lens, you would get about the same image that you see with the naked eye.
The shorter the focal length, the larger the scene will appear on the camera. Accordingly, a longer focal length narrows the field of view, so a zoom lens has a certain scale of focal lengths that you can use to manually change the angle of view. In colloquial language, we know this as zooming in or out.
Zoom lens vs. fixed focal length
The zoom lens is often compared with its counterpart, the fixed focal length. It has both advantages and disadvantages.
Advantages of a zoom lens
- The biggest advantage of zoom lenses is the possibility to change the angle of view quickly and without changing the lens. This is especially useful for photojournalism and event photography because you can react spontaneously and without much fuss to the situation.
- Another big advantage is that in a zoom lens you already have a selection of different lenses, so you can limit your equipment to just a few pieces. This is very practical when you are on the road and plan different shots.
- The disadvantages are mainly that the zoom lens usually cannot compete with the fixed focal length in sharpness or speed. Due to the rather small maximum aperture of the zoom lens, less light can enter the camera. To compensate for this, you will need a slower shutter speed, especially in difficult lighting conditions. There are also faster zoom lenses, but they are very expensive.
Key figures for zoom lenses
Zoom lenses are divided into different variants with different characteristics, which can be identified by markings on the lens:
The range of the possible focal length and the maximum aperture can be found at the bottom and additionally on the front outer ring of the lens. The values are abbreviated, such as 18-140 mm f/3.5, where 18-140 mm is the possible focal length and f/3.5 is the maximum aperture.
What is a fast lens?
The speed of a lens refers to the value of the maximum aperture: the smaller the f value, the faster the lens. The designation is derived from the fact that the incidence of light is greater and thus a faster shutter speed is possible. The maximum aperture of fast lenses is always below f/4. Due to the high image quality, they are particularly suitable for shots in unfavorable lighting conditions but are usually more expensive than slow lenses.
A maximum aperture above f/4 is called a slow lens. Since it allows less light to enter, you have to set a slower shutter speed for the same exposure.
Variable or constant aperture
With a lens, not only the focal length but also the aperture can be either fixed or changeable. This information is also indicated on the lens. On a lens with a variable aperture, you will find something like the following marking: 55-200 mm 1:4-5.6G. The first value of the aperture (f/4) refers to the maximum aperture when using the shortest focal length (55 mm).
The second value (f/5.6) is for the longest possible focal length (200 mm). This means that the closer you zoom in, the smaller the maximum aperture becomes and the less light enters the camera.
- Small aperture == Open aperture (eyes wide open, lots of light coming in) == Low f-number (e.g. f/3.5) == Fast shutter speed == Fast exposure time
- Large aperture == Closed aperture (eyes closed, little light coming in) == High f-number (e.g. f/22) == Slow shutter speed == Long exposure time
A lens with a fixed aperture has something like the following label: 70-200 mm f/2.8. From this you can see that the aperture is always at f/2.8 even when the focal length is changed. Such a construction is not easy to manufacture, which is why these lenses are usually more expensive.
Which Zoom Lens Type Is Best?
If you’ve worked with different lenses before, you’ll know that the type of lens and its use has a lot to do with the focal length. Since a zoom lens covers an entire range rather than just one focal length, it can often be used in a variety of ways.
For example, a single zoom lens can be both a wide-angle and telephoto lens in one, with a focal length range of 16-300mm. The following are some of the uses for zoom lenses:
The wide-angle lens
Because of their short focal length (starting at less than or equal to 35 mm), wide-angle lenses capture a large field of view. When the focal length is less than 24 mm, they are called super wide-angle lenses. This type of lens is especially popular for landscapes.
The standard lens
Standard lenses are similar in the angle of view to the human eye and have a focal length of about 50 mm. They are suitable for a variety of areas such as portraits, street photography and snapshots.
The telephoto lens
Unlike wide-angle lenses, telephoto lenses are characterized by their long focal length. They are particularly suitable for shooting distant objects and are therefore used especially in wildlife and sports photography. Because of the long focal length, they only capture a relatively small section of the image.
There are different opinions about the minimum focal length from which one speaks of a telephoto lens. This value is defined by some as 60 mm, by others as 85 mm or even as 135 mm.
Buying the right zoom lens
So there really is a lot to choose from when it comes to zoom lenses – but which one should you buy? The following points of reference can help you decide:
#1 What focal length scale do you need?
The answer to this question depends mostly on the area of photography you want to work in.
- Portrait photography: 35 mm to 200 mm
- Landscape photography: 14 mm to 35 mm
- Wildlife photography: > 300 mm
These guide values are a good starting point, though of course there are exceptions. For example, some portrait photographers like to shoot with a wide-angle lens. To answer this question for yourself individually, it’s best to use your image library as a guide. There you can find out which focal length you have used the most so far and then decide whether you want to continue that way or try a new angle of view.
#2 Full frame or crop sensor?
The focal length specifications always refer to the use of a full-frame camera – if you work with one, you can skip this step. However, if you have a crop sensor camera, the angle of view on the final result will be smaller than the specified focal length.
You can calculate this difference by multiplying the focal length of the lens by the crop factor of your camera. For example, if the crop factor is 1.5x and the focal length is 50 mm, you calculate 1.5 x 50 mm = 85 mm. So your image will look like you took it with an 85 mm lens.
ATTENTION! The model of your camera can change the picture result!
For this reason, this step is extremely important when choosing your zoom lens. For example, if you buy a 16-300mm lens, it will work with your crop sensor camera much like a 24-450mm lens – a big difference!
#3 What aperture works for you?
After you have decided on the focal length range, the aperture follows. Do you prefer a slow (e.g. max aperture 5.6) or a fast (e.g. max aperture 2.8) lens? This depends on both your needs and your budget: fast lenses have many advantages such as high image quality even in low light conditions and shallow depth of field, which allows you to achieve blurry backgrounds.
However, they are much more expensive than slow lenses. So if you only shoot in good daylight anyway and can do without blurry backgrounds, a slow lens is perfectly adequate.
#4 What can you afford?
By now, you hopefully know exactly what features you want your lens to have. Next, you should check the market and find a suitable model. Of course, your budget plays a big role – lenses come in all sorts of tempting varieties and you can spend a lot of money on them. The good news is that it’s often not necessary to buy the most expensive. Even if you have to make some compromises, there are good and cheap options.
You can save on the brand of the lens, for example. It doesn’t have to be the same brand as your camera, just make sure they are compatible and the image quality is right. Also, look to see if there is an autofocus option built in. Also, built-in image stabilization in the lens is super important for zooms if the camera itself doesn’t have this feature.
You may have to settle for a little less in terms of zoom range and aperture values. Despite all the compromises, you should be sure that the lens meets your needs. If you’re sure you need a more expensive model, you can buy lenses used or rent them until you have enough saved up.
#5 Review and selection
When choosing, you must pay special attention to the following points:
- Is the lens mount correct? e.g. E- and FE or A-mount (Sony), FX and DX (Nikon), EF etc. at Canon
- Does your camera have internal image stabilization? If not, then your lens needs this function
- What is the weight of the lens? Does it roughly balance out with the camera for a good balance?
Also read reviews from other buyers. A good starting point for analysis is always the best sellers.
Zoom lens: frequently asked questions
What is a zoom lens?
What is optical zoom?
How does a lens work?
What is a telephoto lens used for?
Conclusion: Zoom Lens
Finally, here are the most important facts about zoom lenses:
- The focal length of a zoom lens is not fixed but can be changed.
- Therefore, it is versatile and suitable for different areas of photography.
- There are different types of zoom lenses, which differ mainly in the values of focal length and aperture.
- The most important factors when buying a zoom lens are the focal length and aperture you need, the camera model, and your budget.
I hope this article has been helpful and that you are closer to making a decision! Even if you should always keep the weaknesses of a zoom lens in mind, it is definitely a practical addition to your photo equipment. Have you had any experiences of your own? Let us and our readers know in the comments!