Why it's hard to take a good photo of the moon on your phone
You go out at night under the open sky, see the bright moon and decide to capture this moment on your smartphone. But instead of an impressive shot, it's a white spot on a dark background.
Why do modern phones, capable of taking great photos, do so poorly with the Moon? The answer, as it turns out, lies in the peculiarities of both the subject and the technology of cameras.
About it tells Professor Michael J. I. Brown from Monash University in the material The Conversation.
The main mistake, according to the scientist, is to think that we take pictures at night. It's night on Earth, but it' s day on the Moon, because we see its sunlit side. So taking a picture of the Moon requires the same parameters as a daytime photograph, not a nighttime photograph.
Phones automatically adjust the exposure to match the overall light in the frame. When the camera "sees" a black night sky, it increases the shutter speed to make the image brighter. As a result, the moon, which is much brighter than its surroundings, is over-lit and becomes a white spot.
To avoid this, you can manually reduce the exposure if the feature is available. However, even with the right settings, photos of the moon on your phone are rarely detailed. It's all about optical limitations.
The smartphone is designed for wide-angle shots - portraits, landscapes, selfies. The angle of view of such cameras can reach 90°, while the visible diameter of the moon in the sky is only 0.5°. As a result, its image on the camera sensor occupies only about 25 pixels, which is not enough to convey details.
The telephoto lens has a focal length of only a few millimetres and the sensor pixel size is a thousandth of a millimetre. Software zoom (digital zoom) doesn't help - it only "stretches" the image, but doesn't add real detail.
However, there is a way to get high-quality pictures without a professional camera. Just bring your smartphone to the eyepiece of the telescope and take a picture through it. The telescope increases the focal length from 6 mm to hundreds of millimetres, and the image of the Moon, instead of 25 pixels, can take already 1,000-1,200 pixels - this is a completely different level of detail.
Today, special holders are even sold for attaching the phone to the telescope - with their help you can get impressive shots.
So the secret is simple: it's not the phone's fault - it's just that the Moon is too far away and bright. So, for really "Instagram-like" lunar shots you need not only patience, but also some optics.