Focal lengthof lens formula

The Ruby Series™ is our line of lenses with an emphasis on performance and price, with achromatic operation over the range of 3–5 μm.

Focal length equationfor lenses

The focal length of a lens is directly related to its magnification power. A shorter focal length results in a wider field of view and less magnification, while a longer focal length results in a narrower field of view and greater magnification.

Focal length can be calculated by dividing the distance from the lens to the image sensor (or film) by the distance from the lens to the subject. This is known as the thin lens equation: 1/f = 1/di + 1/do, where f is the focal length, di is the distance from the lens to the image sensor, and do is the distance from the lens to the subject.

What isfocal lengthof lens

The size of the image sensor can affect the effective focal length of a lens. A larger sensor will capture a wider field of view and result in a shorter effective focal length, while a smaller sensor will capture a narrower field of view and result in a longer effective focal length.

Achromatically correct over a range of 3–5 μm, Ruby lens systems offer a 1" cold shield height, an f/2.3 collecting aperture, and are suitable for use with up to 21 mm diagonal image formats.

Focal length is a measurement of the distance between the center of a lens and the point where light rays converge to form a clear image. It is typically measured in millimeters (mm) and is an important factor in determining the magnification and field of view of a lens.

The focal length of a lens is a fixed characteristic and cannot be changed. However, the field of view and magnification can be altered by using different lenses or adjusting the distance between the lens and the image sensor.

This series is ideal for f/2.3, f/2.5, or f/4.0 cameras. All focal lengths include manual focus with lock and the IR industry's standard bayonet mount.