91download.com supports a wide range of platforms, including YouTube, Facebook, Twitter, TikTok, Instagram, Dailymotion, Reddit, Bilibili, Douyin, Xiaohongshu and Zhihu, etc. Click the download button below to parse and download the current video
Have you ever wondered about the enigmatic ghostly images of the recent solar eclipse captured in photos, floating in the sky far from where the sun actually is? What causes these mysterious lens flares, and why do they occur during such celestial events? Let's delve into the fascinating world of lens flares and uncover their secrets.
What if I told you that these ghostly eclipse images are not as spooky as they seem? They are, in fact, lens flares - a phenomenon that occurs when you point a camera towards a particularly bright light source, resulting in glows, streaks, disks, or even eclipses. But lens flares are not just a mere curiosity; they offer two intriguing insights.
Firstly, they allow us to capture images of partial or annular eclipses without the need for expensive photographic filters to darken the sun. However, a word of caution: never look directly at the sun or point a camera at it for an extended period without the proper solar filter, as my lawyer keeps reminding me.
Secondly, lens flares reveal fascinating details about their nature. Lens flares are essentially optical defects, resulting from light passing through a lens in an unintended manner. Modern camera lenses consist of multiple glass elements working together as a single optical device. In an ideal world, all light would be bent as intended, but physics has a knack for throwing curveballs.
Glass has a tendency to reflect, absorb, and scatter light, despite anti-reflective coatings. Each lens element can incorrectly reflect, scatter, or diffract a small amount of light, causing it to bounce around within the lens before hitting the image sensor or escaping back out. Typically, this incorrectly bouncing light is too faint to notice, especially if the lens manufacturers have done their job well.
But when a bright light source enters the equation, lens flares come in various forms - glows, rings, rays, starbursts, disks, and rainbow arcs. The appearance of these flares depends on factors such as the shape and positioning of lens elements, coatings, focus, zoom, aperture settings, and even the direction of the light source.
有趣的是,任何能够直接看到镜头前方的物体——无论是否在视野范围内——理论上都会在图像中产生某种类型的镜头眩光。然而，大多数镜头眩光过于微弱，无法察觉。
Lens manufacturers work tirelessly to minimize reflections and absorption that cause flares, but defects are impossible to eliminate entirely. You only start noticing flaring when the light causing the flare is bright enough, even when dimmed significantly, to outshine or match the brightness of other elements in the image. The sun, undoubtedly, fits this criterion.
During the eclipse, some of the sunlight scattered or illuminating a lens element within the lens creates a flare resembling the eclipse itself. This phenomenon is distinct during an eclipse because the flare becomes an actual image of the sun, rather than a mere out-of-focus orb. This realization is exciting, as it means that when we capture a lens flare image of an eclipse, we are, in a sense, directly photographing the eclipse itself - albeit through a lens defect.
Now, let's address a curious observation: sometimes, the flare isn't opposite the sun but is located precisely where the sun should be. This isn't a flare at all but a direct image of the eclipse. Clouds passing in front of the sun can darken it sufficiently for the camera to capture a photo without the glow or flares obscuring the image. It's all about relative brightness!
So, the next time you encounter a lens flare while photographing a bright object, you can determine whether it's a flare or the actual object itself. If you can place your hand "behind" it (because the flare occurs inside the lens), it's a flare. But if it's the actual object, you'll need to get behind it - which, with the sun, is a bit challenging.
While waiting for the next eclipse to capture these fascinating lens flares, why not dive into new math and science courses from Brilliant? Their latest offerings explore visualizing data and understanding how AI large language models, like ChatGPT, work. Sign up for Brilliant (for free) and gain 30 days of full access to their courses by visiting Brilliant.org/MinutePhysics. The first 200 people will also enjoy a 20% discount on an annual Premium subscription to all of Brilliant's content, including their ever-growing range of new courses. Visit Brilliant.org/MinutePhysics and expand your knowledge today!
Share on Twitter Share on Facebook