There are three general classifications for lenses related to the image field of view.
A lens with a focal length close to the diagonal length of the sensor format produces an image with a near-human field of view and is considered a "normal" lens for that sensor format.
Specifically, f-number is defined as:where f/# is the f-number, f is the focal length and d is the entrance pupil diameter.
Camera lenses that can collect a lot of light (i.e., a low f-number) are known as fast lenses as they can be used with shorter exposure times and are ideal for low-light conditions.
These lenses are the ideal choice for high-end inspection or high-resolution imaging applications.
For more information on these lenses, Modulation Transfer Function (MTF) plots can be found in the tab above.
All lens models are equipped with lockable focus and aperture rings.
Some lenses are designed for improved aperture or resolution performance.
See the table above for a list of sensor formats for Thorlabs cameras.Selecting an appropriate camera and lens pair can significantly improve image quality.A lens should generally not be used with camera sensors that have a larger format than the lens.The aperture of the lens controls the amount of light that a lens can collect; the more light a lens collects, the brighter the image.Because of this, the aperture size affects the exposure time and therefore the speed of the camera.
To illustrate this, the sequence of three images to the right were taken with the same camera with three different lenses.