The most important aspect of any camera, regardless of its megapixels and features, is the lens itself. Lenses focus light until they reach a point which is called the focal point in order to receive a sharp representation of the view in front of it. However, that is only a small part of the bigger picture.
Lenses also magnify the subject you're viewing in order to observe scenes at greater distances and in order to achieve this, the distance between the focal point and the camera's sensor needs to be increased. But the greater this distance, the larger the lens needs to be which is why longer lenses are used for photographic practices such as wildlife and sports photography.
So in a nutshell, a telephoto lens such as a 400mm, will have a distance of 400mm between the focal point to the sensor in order to achieve the required magnification.
But things need to be drastically scaled up the further away a subject you want to observe is, which is the case for the incredible LSST observatory digital camera which is the biggest digital camera in the world. The biggest lens in this system is over 5 foot in width and is made out of the finest crystal glass known to man to keep images as sharp as possible and has a focal length of 10310mm.
The images focussed by these lenses will be gathered by a mammoth 3200 Megapixel sensor, which to put things into perspective, is around the equivalent of 400 4K TV's laid out per single image captured by the LSST telescope!
The LSST digital camera is capable of clearly seeing a golf ball at the same distance away as the moon.
Take a look at the video below by the YouTube channel: Physics Girl on The Worlds Largest Camera Lens...