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Wavelength & zoom: Prioritize whether the lens needs to be zoomed. For applications that need to change the magnification during the imaging process, a zoom lens is used, otherwise a fixed-focus lens is used. To determine the working wavelength of the lens, three issues need to be considered: ① Is filtering taken? ② Is it monochromatic or polychromatic? ③ Can the influence of stray light be effectively avoided? After comprehensive consideration, the working wavelength of the lens is obtained.

Prioritize special needs: clarify the special needs of the actual application. For example, whether it has a measurement function, whether a telecentric lens is required, whether the imaging depth of field is large, etc. Depth of field is often not taken seriously, but it is a factor that must be considered for any imaging system.

Working distance & focal length: Working distance and focal length need to be considered together. First, clarify the system resolution, combine the CCD pixel size to know the magnification, and then combine the spatial structure constraints to calculate the object-image distance, and further estimate the focal length of the lens.

Image size & image quality: The image size of the selected lens must be compatible with the size of the camera's photosensitive surface, following the principle of "large compatible with small". The camera's photosensitive surface cannot exceed the image size indicated on the lens, otherwise the edge field of view will have poor image quality. Image quality should focus on MTF and distortion. In measurement applications, distortion should be paid special attention to.

Aperture & Interface: The lens aperture mainly affects the brightness of the image surface. However, the final image brightness is determined by multiple factors, including gain, integration time, light source, etc. In order to obtain the target image brightness, many links need to be adjusted together. The lens interface refers to the connection between the lens and the camera. The two need to match. If they cannot match directly, consider using an adapter.

Cost: If there are multiple lenses that can meet the requirements after the above factors are considered, the cost is considered to select the best one.