Source：Shenzhen Kai Mo Rui Electronic Technology Co. LTD2026-07-10
Focal Length | Zoom & Focus
Zoom refers to altering the lens focal length (strictly speaking, the image distance) to adjust the shooting field of view, which is commonly known as zooming in or out on the subject. Typical zoom lens examples include the 18-55mm and 70-200mm specifications.
Key Takeaway: The longer the focal length, the narrower the field of view.
Focus generally means adjusting the distance between the lens group and the image sensor plane, so that the target object forms a sharp image on the CCD/CMOS sensor.
The term "focus adjustment" in daily usage almost always refers to focusing. A common misconception is that prime (fixed-focal-length) lenses cannot focus — prime lenses are fully capable of focusing normally.
Aperture | Image Sharpness
Delivering crisp, sharp imagery is a core design goal for all camera lenses.
Lens aperture values typically range from F1.2 to F32 (e.g. F1.8–F16). For standard DSLR lenses, the sharpest performance is usually achieved at F5.6 or F8. This is determined by two optical phenomena: spherical aberration and diffraction.
Diffraction is the primary factor reducing sharpness at extremely small aperture settings.It describes the physical phenomenon where light waves bend away from their original straight path when encountering obstacles. In classical physics, light disperses after passing through slits, pinholes or opaque discs. Related concepts include Airy Disk and the Rayleigh Criterion.
In simplified lens imaging diagrams, parallel light is drawn to converge perfectly at a single focal point, yet this is an idealized simplification rather than real-world behavior.
Since light rays cannot converge into an absolute pinpoint, perfectly crisp imaging is impossible.
When the aperture is wide (small F-number), the lens captures light across a large circular area, causing light rays to converge over a broad range and resulting in soft, unsharp footage.
When the aperture is narrowed, the effective light-receiving area of the lens shrinks, light converges into a tighter spot and delivers sharper images. Besides, focusing errors are less noticeable at smaller apertures thanks to deeper depth of field, which further improves the perceived sharpness.
Key Point: A smaller aperture yields sharper images.
Practical lenses adopt intricate multi-element structures consisting of several to over a dozen lens pieces, some made of high-cost materials such as fluorite. These components are designed to upgrade optical performance and correct spherical aberration, coma, chromatic aberration, distortion and other optical defects.
Illumination Source | Complementary Red Light & Blue Light
Blue light has a shorter wavelength and weaker diffraction effect, so it excels at capturing tiny details and is the preferred light source for micro-object shooting.
Black-and-white CCD sensors are slightly more sensitive to red light, though this advantage is marginal. It can help suppress ambient light interference in certain scenarios. Another merit of red light sources is their lower cost compared with blue light alternatives.
Many users assume a color camera is mandatory to distinguish colored objects, which is incorrect.
When converting an RGB color image to a grayscale map with brightness gradients, the standard conversion formula is:
Grayscale Brightness = 30% Red + 59% Green + 11% Blue
This means objects of different colors produce distinct grayscale brightness values after conversion. Moreover, illuminating the object with monochromatic colored light before shooting with a monochrome camera will generate totally different grayscale results.
Rule summary for red lighting + monochrome camera shooting:
Red areas on the target turn bright white; white areas turn light gray; colors drastically different from red render dark black; pure black areas remain black.
Definition & Clarity | Gain Tuning
Aperture, shutter speed and ISO (Gain) are the three core parameters for proper exposure, which interact and restrict one another.
ISO values typically range from 100 to 3200 in video surveillance. In industrial machine vision, ISO is renamed as Gain, a parameter usually kept at default settings.
In industrial vision systems, camera gain works by amplifying the electrical signal output from the image sensor. Higher gain delivers stronger signal amplification, elevating image contrast and brightness to make footage clearer and easier to observe.
Especially under low-light conditions, high gain effectively boosts image visibility and definition.
However, gain amplification also introduces image noise. Higher gain magnifies random signal fluctuations from the sensor, degrading image quality with blurriness and fixed noise artifacts. Therefore, gain must be balanced according to specific application requirements to obtain optimal imaging results.
Key Point: Adjusting gain modifies image clarity at the cost of introducing noise.
Depth of Field | Illumination Brightness & Aperture
High-brightness lighting allows shorter exposure time and faster frame grabbing speed.
Additionally, sufficient light enables the use of a smaller aperture. Narrowing the aperture generally produces sharper frames and a larger depth of field, two critical indicators for stable machine vision system operation.
Key Point: The smaller the aperture, the greater the depth of field.
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