A zoom lens is probably one of the first lenses you will get with a DSLR. But, bridge cameras and advanced compacts also have zoom lens capabilities. So what exactly is a zoom lens and how will you use it?
Firstly though there is a difference in zoom lenses between advanced compacts/bridge cameras and the DSLR. The lens of a compact or bridge camera is fixed to the camera body and cannot be changed. The range of these optical zooms also differs between different cameras – for example, your 8 times optical zoom might only go from 24mm to 120mm. Whilst on other cameras it might be 60mm up to 200+mm. It’s a good idea to check the focal range of your optical zoom before buying your compact or bridge camera.
A DSLR zoom differs in that it is not joined to the body of the camera. Instead, you have interchangeable lenses and can fit any size of zoom that you wish (making sure that the lens is designed for your make of camera, though. If you buy a DSLR as part of a starter kit then usually you will get a small zoom lens with this. Though again this starter lens can be any focal length. And some manufacturers offer different starter kits with different size zoom lenses as part of the kit. So think about what you want your zoom for before choosing the kit lens to start.
What Does a Zoom Lens Do?
Put simply a zoom lens allows you to stay in one place and bring the subject closer to you or further away. How you do this is by twisting the zoom ring on a DSLR lens or by clicking your zoom button on other cameras. Therefore, unlike a prime lens which has a fixed focal length, the zoom covers a range of focal lengths. The focal range though is different for different zoom lenses.
For example, you can have a wide angle zoom lens which offers a focal range of only 10-20mm which is great for landscapes. But you can then have zoom lenses which are in the telephoto range such as a 70-200 or a 100-300mm. These lenses have a range of uses.
Now this range of focal lengths in one lens does have a few drawbacks. First up, zoom lenses are more complex than primes as they need a greater range of mechanics. Therefore, they are heavier and larger than maybe a prime lens of the longest focal length. Secondly, they are more expensive. And finally they might not have the widest apertures available – for example, a 70-200mm zoom might have their widest aperture at f2.8 whilst a prime can go down to f1.4.
A zoom might also not be as sharp as a comparable prime either. Though if you use the zoom in the middle of its focal range you probably will not notice the difference. It is at the edges of the focal range that deterioration can occur.
When Would You Want to Use a Zoom Lens?
Zoom lenses sound great as they can bring the subject much closer to you without you having to walk closer to the target. This does have a range of practical applications as follows:
Photographing wildlife is one of those times when you probably physically cannot get closer to your target. This is especially true when safety is an issue or when photographing animals at a wildlife or conservation park. You can alter the zoom length if your subject moves further away from you or moves closer to you whilst staying still.
Like wildlife photography, you may not be able to move when you are shooting sports. For example, you might have a fixed seat in the stands. Therefore to catch the action you will want to change your focal length to keep the subject in the frame.
Travelling or Hiking
If you are travelling aroud or hiking and want to take a camera then usually you have to think of the weight and size of your gear. Therefore, you could just take one zoom lens with you rather than two or three different lenses.
By using a zoom lens you can often stay out of the way of people and shoot relatively un-noticed. However, this is dependent on the size of the zoom lens as someone will notice a very large lens pointed at them even if you are on the edge of a crowd. Now, this does sound rather voyeuristic as it can be abused, eg, paparazzi photographs. But it can be useful for shooting documentary weddings when you want to catch natural emotions and not let people see you. It can also be good for shooting concerts as you can focus on the band and then zoom out to focus on the crowd.
A zoom lens can compress perspective. This is extremely useful for a portrait photographer especially with a 70-200mm lens as this flattening can give a pleasing perspective to faces.
If you want a far away subject to stand out from the background then a zoom lens can also be useful due to this compressing of perspective. A long telephoto zoom can “pull” the subject out of the background which makes the subject stand out more. Depth of field at these longer ranges is also smaller so backgrounds will also be more blurred whilst the subject is in focus.
What Are The Drawbacks
We have already mentioned that zoom lenses are heavier than primes due to the extra mechanical complexity. And they can be more expensive. But they can also be less sharp than a prime lens though this is also dependent on the cost of the zoom. Your kit lens is usually a cheaper zoom so the quality of the optics in these are not going to be as good as an f2.8 or other fixed lower aperture zoom.
As zooms are also heavier they can be difficult to hold for long periods of time. I know that after carrying a 70-200mm f2.8 around for a couple of hours my shoulders really begin to ache.
Also, you have increased camera shake with larger zooms, especially when at the longest limit of its focal length. This is noticeable especially since depth-of-field at these focal lengths can be quite small. Therefore, any small amount of movement or shake can lead to an out of focus or blurry image. As you magnify your subject you also magnify the optical effects of any movement.
You can get around camera shake though by using image stabilisation which is on more expensive zooms. Or you can also use a tripod or monopod. If you don’t have a tripod available then you can rest your camera on a wall, or crouch down with feet flat on the floor and rest your elbows on your thighs for more stability. I often use a small camera bean bag when out photographing with a long zoom lens to give this extra stability.
Nearly every photographer will have at least one zoom lens in their kit bag. My two favorites are my 24-70mm f2.8 and a 70-200mm f2.8, both of which are in my everyday gear bag.
Are you looking for a new zoom lens or do you have a favorite zoom currently?