Traditional Culture Encyclopedia - Photography and portraiture - What is lens dispersion when shooting with a SLR?

What is lens dispersion when shooting with a SLR?

Dispersion refers to the dispersion of the color of the light source after passing through the prism. The most common thing in nature is the rainbow.

Red, orange, yellow, green, blue and purple, who is dancing with color training? It turns out that this is the result of dispersion. The white light of the sun is refracted by water droplets and turned into gorgeous colors.

1666, the great British scientist Newton (the one who let the apple hit his head) made an experiment with a prism, which can be said to be the most beautiful experiment in history (one of them, the scientist rated it as the fourth, but I don't know why it was so brilliant). He succeeded in splitting sunlight into various colors with a prism.

For hundreds of years, people have finally realized that different colors of light have different frequencies and have different refractive indexes when refracted through the interface. Just like a group of people with different turning angles, they ran away after turning a corner.

Lens is actually a variant of convex lens, which is equivalent to a continuous 360 prism, and naturally there will be dispersion problems.

In the backlight, the edge with obvious alternation of light and shade will see the wrong purple, which is often called "purple edge".

But this situation is not unsolvable.

The upper part of this picture is ordinary optical glass. After refraction, a beam of white light becomes a fuzzy substance and its color changes. The lower part is a lens of low dispersion glass, which is similar to a little white light after imaging.

Major lens manufacturers and optical researchers have made painstaking efforts, and low-dispersion glasses such as UD (Canon), ED (Nikon) and LD (Longteng) have come out one after another. Canon also made fluorite lenses to solve the dispersion problem. So in the lens index, the appearance of these words means the high quality of the lens.

If the lens in your hand is not so advanced, you can also solve it by avoiding backlight, narrowing the aperture and adjusting it later.