The aperture for a group portrait depends on how the people are arranged, how close the camera is and how large the final picture will be. A row of three people facing the camera is a different problem from three rows extending into the room. Choosing a small aperture without examining that depth can leave you with a slower shutter and still insufficient sharpness.
Begin by bringing faces closer to a common distance from the camera. Ask people at the ends not to lean far forward or backward, and keep a seated front row reasonably close to a standing row behind. The arrangement must remain comfortable and natural. You are reducing unnecessary depth, not forcing every person into a rigid line.
Test the near and far faces
Choose a moderate aperture as a trial, then focus on a face within the group rather than on the nearest decorative object. The best focus position depends on the actual distances; blindly choosing the person one third of the way back is not a universal solution. Make a test frame and enlarge the nearest and farthest eyes that need to look sharp.
If the rear row is soft, close the aperture or reduce the depth of the arrangement. If the front row is soft while the back is sharp, reconsider focus placement as well. A wider view from farther away may offer more usable depth for the same group, but changing position also changes the background and the relationships between people. Recheck the composition after moving.
Keep enough shutter speed for small movements. People sway, blink and turn towards each other even when asked to stand still. If closing the aperture makes the exposure too long, increase ISO or improve the light rather than relying on camera stabilisation to freeze the people. Stabilisation addresses camera movement, not a child turning their head.
Consider two rows in a small room: seated people in front and standing people behind. If the rear faces are much farther back than necessary, ask the standing row to move closer before changing aperture. Watch that heads do not overlap and that the front row still has comfortable space. This reduces the focus problem while preserving a readable arrangement.
If one person at the edge remains soft in several frames, investigate their distance and the lens's edge rendering separately. They may be leaning forward, the camera may be angled across the group, or the selected aperture may expose a lens limitation near the corner. Move the person slightly inward or change the camera alignment for a comparison. Do not immediately close the aperture to its smallest setting, because that can introduce a slower shutter and reduce fine detail elsewhere.
For a large group, take a deliberate test before asking everyone to hold the final expression. Tell them briefly that you are checking the arrangement, inspect the near and far faces, then make the actual sequence. This avoids spending the group's patience on repeated frames with the same unresolved focus problem.
Take several short sequences with a pause between them, and check expressions as well as focus. A technically sharp frame with half the group blinking is not the finished result. Encourage everyone to look towards the same point and announce when you are about to photograph, without making them hold a smile for an unnecessarily long time.
Finally, inspect the image at the intended output size. A small shared photograph and a large wall print demand different levels of visible detail. Keep the frame with the best balance of expressions and adequate depth, and record the arrangement and settings if you need to repeat the group later.
