focal length

USAGE SUMMARY

"focal length" is an appropriate and usable phrase in written English.
It typically is used in the context of photography, describing the distance between a lens and the point at which all light rays converge to create a sharp image. An example sentence would be: "The photographer adjusted the camera's settings, including the shutter speed and focal length."

✓ Grammatically correct

Academia

News & Media

Science

Human-verified examples from authoritative sources

Exact Expressions

60 human-written examples

Try changing the focal length.

Stanford University

Try moving the focal length slider.

Stanford University

The first is related to pointing and focal length.

MIT Technology Review

That is, using the Rowland spacing as the focal length.

Harvard University

This changes the focal length of the green lens.

Stanford University

And you may use only a single focal length lens or a single focal length on a zoom lens.

Massachusetts Institute of Technology

The tiny focal length means that all iPhone pictures are ultra-wide angle.

The Guardian - Tech

The 50mm, at f1.2, is the fastest at that focal length that Canon make.

The Guardian - Arts

The tube's focal length is "piedi 3," the inscription said, three feet.

The New York Times - Science

Fixed focal length lenses require more legwork but reward engagement.

Independent

(Focal length means how much you're zoomed in).

The New York Times

Expert writing Tips

Best practice

When discussing lenses, specify the "focal length" in millimeters (mm) to provide a clear understanding of the lens's magnification and field of view.

Common error

Avoid using "focal length" and focus distance interchangeably. The "focal length" is a fixed property of a lens, while the focus distance is the distance at which the lens is currently focused.

Linguistic Context

The phrase "focal length" functions as a noun phrase, typically used as a technical term. As Ludwig AI confirms, it refers to the distance at which a lens focuses light. Examples from Ludwig show it in contexts ranging from lens design to photography.

Expression frequency: Very common

Frequent in

Science

35%

Academia

33%

News & Media

32%

Less common in

Formal & Business

0%

Encyclopedias

0%

Wiki

0%

Ludwig's WRAP-UP

The term "focal length" is a common and grammatically sound noun phrase, primarily used in scientific, academic, and technical contexts related to optics and photography. As Ludwig AI confirms, it denotes the distance at which light rays converge in a lens. The term's frequency is 'very common,' with a diverse range of applications shown in the examples. Usage guidance emphasizes precision in specifying "focal length" values and differentiating it from focus distance. Related phrases offer alternative ways to describe lens properties, while the linguistic analysis confirms its formal register in technical domains and a more neutral register in general media. The authoritative sources citing "focal length" include academic institutions and prominent news outlets, reflecting its broad relevance.

More alternative expressions

Phrases that express similar concepts, ordered by semantic similarity:

focal distance

Uses a synonym for "length", keeping the meaning identical.

lens focal length

Adds 'lens' to specify the type of focal length

effective focal length

Specifies that the focal length is the effective measurement, accounting for lens combinations or other factors.

optical focal length

Emphasizes the optical aspect of the measurement.

focal range

Refers to a span of focal lengths rather than a single value.

lens focus

Focuses on the point of focus, related to the focal length.

focusing distance

Describes the distance at which the lens focuses, implying the focal length.

image distance

Indicates the distance from the lens to the image plane, which is linked to the focal length.

lens magnification

Describes the lens's capacity to enlarge objects, which depends on focal length.

angular field of view

The extent of the scene captured by a lens, related to its focal length.

FAQs

How does "focal length" affect the field of view in photography?

Shorter focal lengths provide a wider field of view, capturing more of the scene, while longer focal lengths offer a narrower field of view, magnifying distant subjects.

What is the relationship between "focal length" and magnification?

Longer focal lengths generally result in higher magnification, making distant objects appear larger in the image. Shorter focal lengths provide less magnification but a wider field of view.

How is "focal length" measured?

Focal length is typically measured in millimeters (mm). It represents the distance between the lens's optical center and the image sensor when the lens is focused at infinity.

What does "35mm equivalent focal length" mean?

"35mm equivalent focal length" is a way to standardize focal lengths across different camera sensor sizes. It indicates what focal length would be needed on a traditional 35mm film camera to achieve the same field of view.