I often hear that larger mirrors are used in telescopes in order to collect more light, in order to create brighter images, but this doesn't fit with observations of non-telescopic mirrors. Objects don't look brighter in bigger mirrors than smaller ones, so why would bigger mirrors in telescopes create brighter images?

Also, why is it that refracting telescopes have fallen out of favor and instead most advanced telescopes today are reflecting, but for camera lenses refracting lenses are preferred to reflecting ones?

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