The first lens to buy after your kit lens

The zoom that comes with most cameras is a sensible starting point, but it is built to be small and cheap, not bright. For many photographers, the single biggest step up in image quality comes from adding one inexpensive fast prime lens rather than a new body. This guide explains why, which focal length to pick for what you shoot, and how to buy one well.

What the kit lens holds back

Kit zooms are designed to cover a useful range in a small package. To keep them small, they have a modest maximum aperture that gets narrower as you zoom in. Typical examples include Canon's RF-S 18-45mm f/4.5-6.3, Nikon's Z DX 16-50mm f/3.5-6.3 and Sony's E 16-50mm f/3.5-5.6.

At their long end, around f/5.6 to f/6.3, they let in relatively little light. That has three effects:

• Indoors and in the evening, the camera has to raise the ISO or use a slow shutter speed, so photos get noisy or blurred.
• Backgrounds stay busy. A narrow aperture gives deep depth of field, so it is hard to separate a subject from its surroundings.
• Autofocus can struggle in dim light, because less light reaches the focusing system.

None of this makes the kit lens bad. It is light, it covers wide to short telephoto, and stopped down it can be sharp. It just can't do what a bright lens does.

Why a fast prime is the usual first upgrade

A prime lens has a single focal length. Without the complexity of a zoom, makers can give it a much wider maximum aperture for its size and price. An f/1.8 lens lets in roughly ten times as much light as a lens at f/5.6, a little over three stops.

That buys you:

• Lower ISO or faster shutter speeds in the same light, for cleaner, sharper pictures indoors.
• Shallower depth of field, so a portrait subject stands out against a softer background.
• Often better sharpness, especially in the corners, than a kit zoom at the same aperture.
• Small size. Many f/1.8 and f/2 primes are tiny: Canon's RF 50mm f/1.8 STM weighs about 160 g and Nikon's Z 40mm f/2 about 170 g.

Primes also change how you shoot. Without a zoom you move your feet to frame, which many people find makes them think harder about composition. The trade-off is flexibility: you will sometimes want a wider or longer view than the prime gives.

The "nifty fifty" and its crop-sensor equivalent

On a full-frame camera, a 50mm lens gives a natural-looking view that sits between wide and telephoto. Fast, inexpensive 50mm f/1.8 lenses have been a staple of most systems for decades, hence the nickname "nifty fifty".

On an APS-C body, the same 50mm lens frames like about 75mm (Canon, about 80mm) on full frame. That is a short telephoto, lovely for head-and-shoulders portraits but tight indoors. If you want the classic all-round "normal" view on APS-C, look for a lens of about 30–35mm instead.

Depth of field shifts too. To compare an APS-C lens with a full-frame one, multiply both the focal length and the f-number by the crop factor:

• A 35mm f/1.8 on APS-C behaves like about a 52mm f/2.7 on full frame for framing and depth of field.
• A 50mm f/1.8 on APS-C behaves like about a 75mm f/2.7.

The exposure doesn't change: f/1.8 is f/1.8 on any sensor for brightness. Only framing and depth of field are "equivalent". Camera sensor sizes explained covers crop factors in more detail, and how to read a lens name decodes the letters on the barrel.

Which focal length for which subject

Pick by what you photograph most, not by what's popular. The full-frame equivalents below assume a 1.5× APS-C crop.

Subject	Full-frame focal length	On APS-C, look for about	Why
Everyday, street, travel	35mm–50mm	23mm–35mm	Natural view, easy to use indoors and out
Indoor family and events	35mm	23mm–24mm	Wide enough for rooms, bright enough for dim light
Head-and-shoulders portraits	85mm	50mm–56mm	Flattering distance, strong background blur
Half-length portraits	50mm	33mm–35mm	Room to include more of the person
Food and small objects	50mm or a macro lens	35mm or a macro lens	Check the minimum focus distance
Landscapes and interiors	24mm or wider	16mm or wider	Usually better served by a wide zoom

Some sensible first primes by system, as starting points for your own research rather than recommendations:

• Canon RF: the RF 50mm f/1.8 STM on full frame; on APS-C, the same lens works as a short portrait lens.
• Nikon Z: the Z 40mm f/2 or Z 50mm f/1.8 S on full frame; the Z DX 24mm f/1.7 on APS-C.
• Sony E: the FE 50mm f/1.8 on full frame; the E 35mm f/1.8 OSS on APS-C.
• Fujifilm X: the XF 35mm f/2 R WR or the cheaper XC 35mm f/2.
• Micro Four Thirds: a 25mm f/1.7 or f/1.8 gives the classic normal view.

Third-party makers such as Sigma, Viltrox and others also make fast primes for many mounts, often at lower prices, though autofocus support varies by mount. Lenses can be filtered by mount, focal length and aperture.

Check the mount before you buy

A lens has to match your camera's mount, not just its brand. Canon RF, Nikon Z and Sony E each serve both APS-C and full frame, so a full-frame lens fits an APS-C body and is ready for a later upgrade. Older DSLR lenses can be adapted to mirrorless bodies with the maker's adapter, but autofocus speed and features can differ. Mounts lists what fits each mount, and lens mounts explained covers adapters.

Buying a first prime used

Fast primes are among the safest things to buy used. They have few moving parts, the popular ones were made in large numbers, and their quality is easy to test. Lenses also tend to hold their value better than bodies, so you lose less if you sell it on.

Before you pay, check:

• The glass, with a torch through both ends, for fungus, haze and scratches on the rear element.
• Autofocus, near and far, and that it is quiet and consistent.
• The aperture, by looking through the lens as you change it, on lenses with a manual aperture ring.
• Sharpness, wide open and stopped down, on a flat detailed subject such as a brick wall, to spot a decentred copy.
• The mount version. Many lenses come in several mounts, and an adapted lens may not focus as well.

How to buy a used camera or lens safely has the full checklist and your rights in each market, and used or new camera gear? explains when new is the better buy.

When a prime isn't the right first lens

A fast prime suits most people who mainly photograph people, places and everyday life. It is not the right first step for everyone:

• Wildlife and sport need reach; a telephoto zoom will do more for you.
• Landscapes and architecture often need wider than a kit lens goes; a wide-angle zoom fits better.
• Video creators who film themselves may prefer a wide prime or a wide zoom, especially on APS-C.
• Travellers who hate swapping lenses might get more from a travel zoom with a longer range.

Next steps

Start with what you shoot most, choose the focal length from the table, then check your mount. Each lens page under lenses shows today's lowest new and used prices in your market, and deals lists recent price drops. To see how two candidates differ, compare puts their specs side by side.