There are different viewing angle in 5mm LED, 3mm LED, 8mm LED or 10mm LED. During the production, we will control the viewing angle by putting the LED frame deep into the mould of epoxy lens. We will get wider viewing angle when we make the LED frame more close to the top of LED lens. The common angle can be 15 dgeree, 30 degree, 45 degree, 60 degree and 90 degree. If we need to get wider viewing angle then that, we can use the 5mm straw hat shape of size to arrange the production;
Dome lenses can affect the brightness of LED lights by changing the direction and distribution of the light. When a dome lens is placed over an LED, it can help to focus the light in a specific direction or spread it out more evenly. The shape and material of the dome lens can also affect the amount of light that is reflected or absorbed, which can impact the overall brightness of the LED. Additionally, the size and shape of the LED itself can also play a role in determining the brightness of the light.
In all these discussions, the viewing angle of LED(or the dome lens on the top of SMD LED) only affects the "mcd" value of the LED, not the LM value. The "mcd" value is the brightness value of the brightest point at the center of the vertex of the lens. The more scattered the light, the less brightness it will reach the center point, so the larger the angle, the lower the "mcd" value. The LM value is the overall luminous value of the LED chip, which is only affected by the chip size and operating current