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Imagine you have a camera 2.7m ly away from a star that is 2 billion km across, and it's the only significant light source in that direction. How many pixels w
by jstanley 8y ago
Imagine you have a camera 2.7m ly away from a star that is 2 billion km across, and it's the only significant light source in that direction.
How many pixels would you expect the image of the star to be? It can't be less than 1. You'd still see the individual star even though it is a lot smaller than 1 pixel. Imperfect optics mean it will likely appear larger than 1 pixel.
- varjag 8y agoEasily. Which focal length/field of view lens is on that camera?
- TheSpiceIsLife 8y agoI would have thought all these stars and galaxies are at optical-infinity?
- EForEndeavour 8y agoTrue, and focal length is in fact defined (or at least thought of) under the assumption of parallel light rays coming in from an optically infinite distance. https://en.wikipedia.org/wiki/Focal_length https://en.wikipedia.org/wiki/Focal_length
- varjag 8y agoYes? The sensor is not at optical infinity however, and the focal length determines the field of view you get. Quite clearly, one pixel of a camera with 0.001 degree angular resolution and the one of 10 degree FOV give you very different results.
- pjc50 8y agoConversely, how many stars are contributing to that pixel?