A camera lens for a small streaming room.

Pick the focal length from your measured distance. Pick the aperture from how much you move.

Get a tape measure and find the distance from where the lens will sit to the back of your chair. If it lands between two and three feet, you want something in the 22mm to 30mm full-frame equivalent range, and your kit zoom at its wide end is already close. Buy a prime for the aperture and the autofocus, not for the focal length.

Start with the problem

Two complaints bring people here, and they need opposite solutions. One is that the shot is too tight, so you look cropped at the forehead and the room has vanished. The other is that the shot is too wide, so you are a small figure in the middle of a messy wall.

Both are distance problems before they are lens problems. Moving the camera six inches changes the framing more than swapping lenses does, and it costs nothing. Try that first.

The third complaint is the real one: the background looks flat and busy, and your face drifts soft when you lean toward the keyboard. That is an aperture and autofocus problem, and it is the only one worth money.

The paths worth comparing

Framing is arithmetic, not taste. Frame width equals your distance multiplied by the sensor width divided by the focal length, which reduces to a clean rule in full-frame equivalent terms. Here is what that produces at desk distances.

For reference, a head-and-shoulders crop wants roughly 26 to 32 inches of frame width. A chest-up shot with the desk and some room behind you wants roughly 36 to 48 inches. The figures assume the full sensor width, and most cameras crop slightly in 4K or with stabilisation on, so treat them as a starting point rather than a promise.

Read down the columns and the kit zoom stops looking like a compromise. At two feet, 24mm equivalent gives you 36 inches: chest-up, desk visible, exactly the standard streamer frame. That is a Canon RF-S 18-45mm at 18mm, a NIKKOR Z DX 16-50mm at 16mm, or a Sony kit zoom near its wide end. If you sit three feet back and want it tighter, zoom to the middle of the same lens instead of buying anything.

Where the kit zoom fails is light and separation, which is the real argument for a prime and the subject of kit zoom or prime indoors. At f/4.5 it needs a bright room, and at desk distance it keeps the wall behind you almost as sharp as your face.

Check compatibility and the complete cost

Aperture is the trade you are actually making, and it cuts both ways.

Using the standard depth of field formula with a 0.02 mm circle of confusion for APS-C, a 15mm lens focused at two and a half feet gives you roughly five and a half inches of sharp depth at f/1.4, and roughly eleven and a half inches at f/2.8. A 35mm-equivalent prime at f/1.4 gives you only about two and a half inches at the same distance. A kit zoom at 18mm and f/4.5 gives you about thirteen inches, which is why nobody complains about focus with a kit lens.

Five inches sounds like plenty until you lean. Reaching for a mug moves your head four to six inches, and at f/1.4 that is the whole budget. Our recommendation for anyone who moves while they talk is to set f/2 or f/2.8 and put the extra separation into distance from the wall instead. Moving two feet further from the background does more for the picture than a stop of aperture.

Autofocus has to carry the rest. Find the eye detection setting for human subjects and leave it on. At two feet and f/1.4 the depth of field is thinner than your head is deep, so the camera is choosing between your eyelashes and your ears on every frame.

Two practical checks before you order. Every lens named here focuses closer than two feet, so minimum focus distance is not a constraint at desk range. Weight is: the Sigma 15mm is 220g against the older 16mm's 405g, and a desk clamp like the Master Mount L is rated for 2 kg total including the camera. Add a heavy lens to a heavy body and the arm sags over a long stream.

Who should skip this purchase

Skip a new lens if your camera sits more than four feet away. At that distance your kit zoom's middle range is the correct focal length and a wide prime is the wrong purchase.

Skip it if the room is the problem. A fast lens blurs a wall; it does not make the wall interesting, and at 24mm equivalent it barely blurs it at all. A lamp aimed at the background, or two feet more distance, will do more. Our one-light desk setup covers the cheaper half of that.

Skip it if you have not yet solved power, mounting and the route into your computer. A sharp picture that dies forty minutes into a stream is not an improvement. The full cost breakdown lists what else the setup needs.

Our picks

These cover five mounts between them. All four are current, and all four focus close enough for a desk. Match the equivalent focal length in the table above to your measured distance, then pick the one in your mount.

The Sigma 15mm F1.4 DC Contemporary is our default for Sony E, Canon RF and Fujifilm X. Sigma describes it as the successor to its 16mm F1.4, roughly 30% shorter and half the weight, and that weight matters on a desk arm. At 22.5mm equivalent it frames chest-up from about two feet.

For Nikon Z DX the Sigma 16mm F1.4 DC DN is the answer, largely because fast wide DX primes are thin on the ground. Sigma sells it in seven mounts including Micro Four Thirds, where the 2x crop turns it into a 32mm equivalent that suits a three-foot desk better than a two-foot one. Nikon's own NIKKOR Z DX 24mm f/1.7 is the alternative at 36mm equivalent, which is the right call if you sit three and a half to four feet back.

Micro Four Thirds owners should look at the Leica DG Summilux 15mm f/1.7 first at 115g, with the OM SYSTEM M.Zuiko Digital 17mm F1.8 II as the slightly longer option. Note that Panasonic's 20mm f/1.7 II is no longer stocked new, so ignore older recommendations pointing at it.

Buy the Sony E 11mm F1.8 only after you have measured. At 16.5mm equivalent it shows 79 inches of room at three feet, which is a lot of wall to light and tidy. It is the right lens for a genuinely cramped corner and the wrong one everywhere else. If you would rather have one lens that does framing and stills both, the Sigma 18-50mm F2.8 DC DN covers 27mm to 75mm equivalent at a constant f/2.8 in Sony E, Canon RF and Fujifilm X, and that range spans every row of the table above. Fujifilm owners who want maximum separation have the XF18mmF1.4 R LM WR at 27mm equivalent and the XF23mmF2 R WR at 35mm, and Canon owners who need to go wider than the kit zoom have the RF-S10-18mm, though its f/4.5 to f/6.3 aperture means it needs a light.