What do you mean by developing lens?

Lens washing is a kind of light spot produced by multiple reflections of light inside the lens.

Because, when the sun shines directly on the lens, it is like a dazzling beam of light on the stage, and the edge can't be seen with uniform and harmonious lighting effect, and it also spreads around. As you can see from the photo, there is a halo phenomenon where the strong light shines. The scenery here is particularly light, extending to the surrounding area and having a great influence. The scenery is chaotic and powerless, like the scenery and people seen through the fog. This is the halo phenomenon, also known as flushing.

Generally speaking, the phenomenon of light rush only occurs in the backlight state or the back backlight state. When taking backlight photos or back backlight photos, the position of the sun is in front of the camera or in front of the side. If you don't pay attention, it is common for sunlight to break into the lens. It is precisely because these two kinds of light can take photos with strong three-dimensional sense that they are very popular with people, and photographers also like to give it a try, but they should always be vigilant and don't let sunlight sneak into the lens, which will affect the effect.

Sometimes we will find some strange spots in the process of framing, and the spots will change with the movement of the lens. This situation mainly occurs in the environment with bright light sources in front of the lens, such as the sun and dazzling stage lights. There are a series of dazzling light spots in the picture, which will not only disturb the picture (except the pursuit of special effects), but also greatly reduce the clarity of the picture. Sometimes, even if there is no light spot in the picture, it will produce obvious gray fog, which will make the picture look like a veil, reduce the contrast and affect the clarity of the picture, especially on the zoom lens.