Focal length & composition
Perspective versus framing, the field-of-view numbers, and why 10mm feels dramatic and 70mm feels intimate.
- Distinguish perspective (set by distance) from framing (set by focal length)
- Predict the field of view at any focal length on your lenses
- Choose a focal length for the feeling you want, not just the reach
Focal length is usually described as “zoom” — how much of the scene fits. That is true, but the more interesting half is how focal length, and the distance it pushes you to, changes the feeling of a place.
Framing versus perspective
Two ideas often get tangled:
- Framing is set by focal length: a longer lens crops tighter, a wider lens takes in more. That is the obvious part.
- Perspective — how near and far objects relate in size — is set by distance, not focal length. Stand close and near things loom huge over the background; stand back and everything flattens together.
The reason a wide lens looks “dramatic” is that it lets you get close, and close is what stretches perspective. The reason a long lens looks “compressed” is that it makes you back away.
The numbers on your lenses
Field of view narrows as focal length grows. On this APS-C body, remember the ×1.5 crop for the full-frame equivalent:
- 10mm — about a 99° sweep (like 15mm). Expansive, immersive, dramatic.
- 17mm — a natural wide (like 25mm).
- 35mm — close to how you see (like 52mm).
- 70mm — tight and intimate (like 105mm), a flattering portrait length.
Same scene; each frame is what that focal length sees.
Slide through the range and watch the frame close in. The nested rectangles show how much less of the same scene each longer setting keeps.
Choosing for feeling
- 10-20mm for drama and place: architecture with a bold foreground, a room that feels like you are standing in it, a landscape whose foreground looms.
- 35-50mm for the honest, everyday look — street scenes, storytelling frames that feel like being there.
- 50-70mm for intimacy — portraits where the background melts and the face sits forward, isolated from clutter.
In the field
Photograph one subject at 10mm from up close, then at 70mm from far back, framing it the same size each time. The subject stays similar; the background transforms — vast and looming at 10mm, tight and compressed at 70mm. That is perspective, and it is yours to command by where you stand.