One of the main benefits of owning a DSLR is the ability to change lenses to suit what and where you are photographing. As you progress beyond the kit lens and start to look at adding to your lens collection - and even beyond that - one age old question pondered by many always crops up. Should I buy a zoom lens or prime lenses? It's a very difficult question because there are a lot of factors to take into consideration including your preferred shooting style, your available budget, and what your main subjects are going to be. Hopefully what I can do here today is give you some things to think about when you are comparing the two!
First a quick overview of what we mean by prime and zoom lenses - primes are those that have a fixed focal length such as 35mm, 50mm, 85mm, 135mm etc. They do not zoom in or out, so you have to use your feet to get into the right position. They generally have low aperture numbers (f1.8, f1.2, f2.0) and are fantastic for letting in more light, and creating fabulous bokeh.
Zooms - well, everyone is familiar with what zooms are as they are found on all levels of cameras and are sold as the kit lens with your DSLR. These allow you to change through the whole focal range of the lens, just by turning the barrel. Some of these are variable lenses, in which case the focal length is shown by two numbers, for example 24-75mm, or 70-200mm. These generally have higher aperture numbers that also change whether you are zoomed in or out (F3.6 to 5.6 for example) but you can also get fixed aperture zoom lenses - usually F4.0 or F2.8, which means that you can stay at that aperture all throughout the focal range if you wish. (If all that means very little to you, see the post on understanding the lens numbers)
Now I'm going to list some advantages and disadvantages of each type, but please note that everything I say here is a generalisation of these lenses, and you really need to take into account the quality of lenses to compare like for like - for example if I say primes are generally sharper, I mean compared to a similar zoom of it's class - you can't really fairly compare a top-end zoom with a bottom end prime and expect the bottom-end prime to be sharper.
So without further ado, zooms vs primes....
Why Choose a Prime?
- Primes are much more lightweight than zooms
- Primes are generally sharper than zooms
- The bokeh (blurred background) you can get with a prime is usually much better
- Primes stop down to lower apertures for work with very shallow depths of field
- These lower Apertures also allow you to get more shutter speed (and is why they are called fast lenses) so are great for low light work
- They are usually less expensive than zooms (but bear in mind you will need several to cover the same focal range of a zoom)
- As you will have a range of lenses, you have a back-up if one should need to go away for repair etc
- Some people say that primes allow them to get more creative as they have to move with their feet and think more about the shot
What's the Disadvantages of Primes?
- They are harder to frame your images with as you have to physically move yourself into position to get the crop you want
- You may sometimes have to shoot wider and crop in resulting in less pixels in your image
- You may have to change lenses for different focal lengths during a "shoot"
- You will probably want to take more than one lens out with you
- You will need several lenses to cover a good focal range
Why Choose A Zoom?
- Sheer versatility - you only need one lens for multiple focal lengths
- Zooms allows you to frame more shots correctly as you can change your focal length quickly before the "moment" is missed
- Less degradation of picture as you might have to do less cropping (as you can frame quicker)
- You don't need to change lenses so often
- High-end zooms will stop down as low as F2.8 so you can still get great bokeh (although you pay for this particular advantage!)
- You just need to take one lens out with you
What are the Disadvantages of a Zoom?
- They are generally much heavier than a prime,
- With some very heavy zooms, you can get arm fatigue if using for any length of time!
- Although some will stop down to 2.8, many more affordable options have a higher aperture number allowing less light to get into the camera
- Even at 2.8, you can still get more light into the camera with a prime so they are not best suited to low light work
- Most are not as sharp as a prime (with some high-end exceptions)
You will notice I mentioned about that there are some notable exceptions when I mentioned primes are sharper than zooms - one of these is the Canon EF 70-200mm f/2.8L IS II - it is said to be as sharp as any prime, if you add that to the flexibility of the zoom, and a F2.8 aperture, and you are looking at one pretty amazing lens.........unfortunately with a jaw-dropping price to match!
Generally speaking, zooms are perfect for outdoor sports or other subjects where your subject is moving in and out of different focal ranges - for example, chasing your child along a beach is going to be much easier with a zoom - you don't have to run to try and keep up with them as you would with a prime! On the downside, the aperture values generally mean these are less suited to taking pictures indoors, or in low light.
Primes are excellent for times when your subject is relatively still and not moving around so much, and you have a little more time to frame each shot. Classic portrait photography is an obvious example of this, but also if you are outdoors in the garden, or at the play park, you can generally keep up enough to frame each shot more easily. Also, if you love pictures taken with extremely shallow depths of field, you really can't beat a prime for that. Lastly, for indoor shots - even for sports that are indoors - you will probably want the extra light that these low apertures affords you (see this post on why you might want a "fast" lens for more info!)
As you can see by reading this both zooms and primes have times and places where they excel, and one will work better than the other in some situations. Some professionals will exclusively use primes for all their work, and others find zooms to be more advantageous. However, you may find many professionals will have both in their lens arsenal, and of course, this is where the even more old age question of budget comes i! In an ideal world we may want both, but unless you are intending making an income from your hobby, you are probably going to have to compromise somewhere!
Personally I shoot with primes - I prefer having to move with my feet, and having to choose a lens focal length before I start shooting helps me be a little more purposeful.
What do you prefer?