Which lens should you use for dual camera recording on iPhone?

What each lens actually changes

This part has nothing to do with dual-camera recording specifically — it is true of every lens on every camera. Ultra wide has the widest field of view and the shortest focal length, which also makes it the most prone to perspective distortion: anything near the edge of the frame stretches, and faces bulge if they sit off-centre. Wide, the main lens, sits in the middle — the least distortion for a normal shooting distance, which is why it is the reasonable default when nothing about the shot argues for the other two. Telephoto has the narrowest field of view and the longest focal length, which flattens and compresses the image — the look usually described as flattering for a face — but only once there is real physical distance between the lens and the subject.

What is specific to dual-camera recording is what happens after the lens has done its job. The frame the back lens captures does not stay whole; it gets drawn into a canvas that composites two live images, and depending on layout, a meaningful chunk of it is cropped away before it is written to the file. Choosing a lens that looks right on its own and choosing one that still works after that crop are two different questions.

Why ultra wide earns its keep in a split screen

A left-right split screen on a vertical canvas crops roughly a quarter of each source frame off the sides. Starting from a lens with a wider field of view gives you margin to lose to that crop without a second person or the edge of a room drifting out of frame — which is the practical reason ultra wide shows up for two-person interviews shot on one phone sitting between you, and for vlogs where the phone is close to your face while you are also trying to keep whatever is ahead of you in the picture.

The trade-off sits right where the crop leaves the least room for it. Ultra wide’s distortion is strongest near the edges of the frame, and a left-right split already pushes whoever is on the outside toward exactly that edge. Keeping faces centred, which is worth doing on any layout, matters more on ultra wide rather than less — it is doing two jobs at once, avoiding the crop and avoiding the stretch.

Where telephoto helps, and where it quietly does not

Telephoto’s compression is real and worth reaching for when the back camera is the star of a picture-in-picture layout and the subject is genuinely a few steps back from the phone. It is a poor match for the situations dual-camera recording is usually built for. A phone propped on a table between two people for an interview, or held at roughly arm’s length for a walking vlog, does not give telephoto the distance it needs to compress anything — it just narrows the field of view and can crop a person or a scene out of the frame before the layout even gets a chance to crop it again.

The useful habit is matching the lens to the distance you will actually have once the camera is rolling, not the distance you happen to be standing at while testing the frame in the middle of a room.

A short way to decide

Which of these actually shows up in DualCam’s lens picker depends on your specific iPhone. Only back lenses running a format that supports simultaneous capture are listed, so an iPhone with a telephoto lens will not necessarily offer telephoto here — that is a hardware answer for that device, not a setting hiding somewhere.

• Two people close together, split screen, a small room — ultra wide, keeping faces away from the outer edge.
• One subject with a picture-in-picture inset and a few real steps of distance — telephoto, for the flatter, more flattering look.
• A walking vlog narrating what is ahead of you — ultra wide, because the phone sits close to your face and the scene still has to fit.
• Anything close-in that you are unsure about — wide, the main lens. It has the least distortion of the three and the most predictable crop.