Prime lenses are lenses with a fixed focal length, which means that you can’t zoom them at all, which may sound odd, but they do have distinct advantages. Zoom lenses have their obvious advantage, as they allow you to change how the photo is cropped, but this comes at a price; quality and aperture. The post should clear up any misconceptions you have about either, and help you to find the right lens for you. So which is best; prime vs. zoom.
As I stated above, prime lenses simply mean that you can’t change the focal length, which is both a good and a bad thing. It’s bad because it means that you may not be able to get the photo framed exactly how you want it, but it’s good at the same time because it forces you to experiment more, and think of a different way around taking a photo, which you may have missed before. There are two distinct reasons that people buy prime lenses though, and that’s the quality and the aperture.
The quality of a prime lens is often vastly superior to that of a zoom, as they don’t have as many moving parts as zooms, so the glass inside of a prime lens is very precise, which results in much sharper images. This used to be a much bigger difference when zoom lenses were first around, because the technology wasn’t as good, but now you can get zoom lenses that are just as good as some primes, it they comes at a price.
I paid £1000 for my 24-70mm f/2.8, and £1040 for my 35mm f/1.4, and the quality of the zoom lens is very good, but it’s not quite up to scratch with the f/1.4. Even when you’re investing a lot of money in a zoom lens, you’re still making a compromise. You can see how sharp the image is below, it’s hard to believe that this was shot at f/1.4; the widest aperture I have.
Prime lenses have a lot less moving parts, so they’re not constricted by the zooming action, and can focus on the job in hand, which is the aperture. This allows them to open up to much wider apertures than zoom lenses, in fact, the prime lens that I mentioned above, allows almost four times as much light into the lens, than the zoom, even though f/2.8 is very good for a zoom lens.
The main advantage of having a wide aperture is that you can take photos in low light, because the wider aperture allows more light into the lens. This makes it ideal for shooting indoors, perhaps in a bar or club, or in a dimly lit room, where you don’t want to push your ISO. Along with aperture, we also have the advantage of being able to produce a shallow depth of field, which can have a whole range of creative uses. Again, the photo below was shot at f/1.4.
Another big advantage of prime lenses is that they can be picked up very cheaply, although they tend to get expensive very easily, as you probably saw above. A 50mm f/1.8 ranges from around $110-$220, and for that price, you’ll see a dramatic increase in quality over your kit lens, as well as the ability to play around with depth of field.
Zoom lenses are a lot more complicated, and the prices range a lot more, depending on what they do. It’s a common misconception for a beginner to think that a 18-250mm lens should cost more than a 24-70mm, because it zooms further, but that’s not true, because it does it at a price. When it comes to zoom lenses, you really do get what you pay for, and it would be hard to compare the two lenses that I just mentioned, because they’re built for very different purposes.
An 18-250mm is built with a hobbyist in mind, who doesn’t want to carry around multiple lenses, perhaps for someone who travels a lot. A 24-70mm is for a much more serious shooter because they understand the compromises that are made when building a lens with a much longer zoom range, but at the same time, need to be able to freely change the way they’re framing a photo, which you can’t do with a prime lens. A 18-250mm is built for someone who only wants one lens, whereas a 24-70mm is built as a kit lens for professionals.
The overall quality of a zoom lens is catching up with that of a prime lens, but I reckon it’s still got quite far to go. I still notice that my zoom isn’t as sharp as my prime lens, but I knew that when I bought it, and I’m still very happy with the results that I’m getting. You could call it a happy compromise. One thing I have noticed from using both types of lenses is that the photos appear to be a lot softer when the aperture is all the way open, and the photos look better a stop or two narrower. This was definitely more noticeable with a zoom lens, but that’s just part of the compromise.
Because the aperture is f/2.8 throughout the zoom range, I always know what I’m working with, which is not often the case with cheaper lenses. A cheaper zoom, such as a Canon 18-55mm kit lens, will have an aperture of f/3.5 when it’s zoomed all the way out at 18mm, but it will slowly narrow the aperture to 5.6, which is less than half the amount of light. To reach f/2.8 throughout the whole range is a really good achievement, and is not very common with crop sensor lenses.
The price of a good zoom lens can get pretty expensive, but they do reach a limit, because a good zoom lens can only do so much, before the lens maker has to stop making compromises and start making a new lens, for a different focal range. When you start buying lenses, it’s often cheaper, and a more sensible option to buy a zoom lens, because ultimately, you can do more with it.
There will always be prime lenses, and zoom lenses in my camera bag, because they have very different uses. I will use a prime when I know what I’m shooting, and the focal length that I’m working with, or if I’m shooting in low light and want to allow more light into the lens, but I probably still use a zoom lens more often. It’s not a better lens, but it allows me to do more with it, and even though it’s heavier, it’s worth the extra weight.