When shooting with flash in a location where there are many suspended particles, such as in a dusty area or on a snowy day, the image may contain white circles as shown in the picture below. Why does this happen? If the flash fires when a suspended particle floats right in front of the lens, the reflection of the flash from the particle appears more intensely than that of the subject, as the particle is much closer to the lens than the subject. Therefore, the reflection of the flash turns out in the image and causes an effect such as that shown in the sample image above. The closer the lens and strobe are located, allowing suspended particles to be exposed to more light, the more frequently this effect can occur. How can I avoid this effect? Ideally, it is best to shoot in locations where there are very few suspended particles. If not, you can use following method to prevent this effect. a) Avoid using flash by lighting the area as much as possible. b) If your camera has a zoom function, shoot at a wide angle.
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