Focal length is one of those terms you may hear photographers and enthusiasts talk about. But what is it really?
Easily said, focal length is how wide your lens can “see”, or how much it can zoom in. The higher the number of the focal length, the greater the zoom, and the lower the number, the wider it goes.
We usually say that focal lengths up to about 24mm is wide angle, and from 50mm and up is considered to be telephoto lenses. The “ultra wide angle look”, that you get from GoPros, gives you a focal length of about 8mm. The camera that´s in your phone, is most likely around 20mm. Most DSLRs come with a kit-lens that provides a small zoom range and often from 18-50mm.
The first photo below is taken at a focal length of 10mm, and the second is zoomed in all the way, to 135mm. Just look at the difference.
Primes, and zooms
There are two types of lenses. Prime lenses, and zoom lenses. Primes can´t zoom. They are stuck at one focal length, and one only. Zoom lenses are every other lens, basically. If you can change the focal length, it´s a zoom lens. Even if it doesn´t really zoom in much.
I own a 10-18mm lens, and even if 18mm is still very wide, it´s more zoomed in than 10mm. Therefor it´s a zoom lens.
So with that in mind, why on earth would you wanna go with a prime lens, when you´re stuck at one setting? Why would anyone buy anything other than a zoom lens? Well – there are four real pros to a prime lens.
– Aperture – Often primes let in more light, leaving us better of in low lights. (Click the link to read more about aperture, and why that´s kind of a huge deal)
Since prime lenses can´t zoom, there are fewer moving parts in the lens. Less glass, less parts and less engineering makes them easier to build, and makes them way lighter, due to fewer parts. Zoom lenses have much more glass, and even though the glass we find in most lenses are quite clean and amazing, adding layers of them will at some point compromise quality. So primes are often sharper, because of less glass between your subject and the sensor. All of this combined also results in a lower price, than the zooms.
The pros of the zooms are of course the versatility they offer. One lens to rule them all..? That just might be – based on the intended use. If you like to just walk around and take photos when the motives appears, a zoom might be perfect for you. You can go from wide, to zoom, in a second. If you plan to travel for a while, carrying around an arsenal of lenses might be heavy and exhausting. Most zooms now a day are quite good, and for the untrained eye the difference will be hard to spot.
But if you are a professional, taking either head shots, or planning to go for long walks, finding that one perfect shot, rigging up the tripod etc – a good selection of primes would probably be the way to go.
But keep in mind that with a good zoom lens, you won´t have to change lenses all the time. I personally went with a few decent zooms, and one really good prime for headshots. My style of shooting is being at my feet, running high and low. I don´t feel like having to switch lenses every 5 minutes.
Wide vs zoom
To wrap this all up – I just wanna say two words about the usage of focal lengths. Keep in mind that at extremely wide focal lengths, there will be distortion in your photos. Things will bend and curve a lot. Things that are close to the camera will appear huuuuge, and the background will seem very small, and distant. Once you zoom in, you compress the background, and things start to look more correct in comparison to each other, as well as the curves flatten out. I will show you some examples. When you see yellow lines, I have used a wide focal length of 10 or 12mm, and in the last two photos, see the shape of the espresso can, and how it changes dramatically when the focal length change. The nose kinda sticks out in the wide shot, leaving the can to look weird. But also cool. Very cool.
Pay attention to face features and lines. See how they tweak and turn all over? Luckily, my good friend Sammy looks more like the second photo, than the first, hehe.
So to really set things straight here; Make sure to have a thought behind the focal length before you shoot away. When zoomed in, things will look correct in comparison to each other, and at wide focal lengths, foreground elements will become huge, and background elements will seem really small, as well as things will get distorted quite a bit. The wider you go, the more distortion you will bring into the photo. Wise people have figured out that 50mm is about the same focal length as our eyes – and will therefor look the most “realistic”. But hey – wide angles are often my favorite – just because of the fun it brings 😀 So go nuts!
Just to give one last example – look at this coffee cup, shot wide at 18mm, and from a distance at 135mm, and see how the background changes. In the wide shot, you can see loads of what happens back there, but in the zoomed in one, just a small portion of the background is included – even though the cup takes up ca the same amount of space in the image 🙂
Allright – So I hope you got something out of this read, and that I´ll see you back here shortly. What do you struggle with when it comes to photography? I would love to hear your thoughts and comments in the comment section below.
Until next time – I wish you the best of days, and happy shooting 🙂 See you out there!