Spaceship based telescopes

[Anthony]

Originally Posted by David L Pulver

Night Vision are complex (Anthony has argued they should be much worse than GURPS portrays them; Kromm has disagreed, I think) but probably 1-2x heavier?

Realistically, you can't put night vision on an electronic telescope operating at peak resolution, they are already sensitive on the scale of single photons.

If you want figures of merit, the fully dark adapted human eye under good conditions of darkness can spot stars of magnitude 6. According to an exposure calculator, a 1m telescope with a 1s exposure wanting a S/N ratio of 5 can detect objects of magnitude 16.7. Since 5 points of magnitude is a factor of 100, that's about 20,000 times as sensitive, or equivalent to a lens of size (1m/sqrt(20,000)) = 7mm.

Which is about the size of the dark-adapted human pupil. Arguably average human vision should be a limit of more like magnitude 5, and that scope may not be quite maxed out, but in general a maxed out 2.5-3mm lens will match the human eye in both resolution and sensitivity.

Night vision gear has a couple of benefits. First, it adapts much much faster than the human eye (which takes on the order of half an hour, and can be blinded very fast). Secondly, by being indiscriminate about colors (including collecting near IR), it collects several times as many photons as the retina. Third, it has grossly oversized optics relative to its resolution -- a 30mm operating at 10x magnification will have about the same night vision as a human, one operating at 1x will have 100x the night vision. Reasonable TL 9 sensors can probably swap between night vision and telescopic vision on a 1:1 basis, and can add one extra level of night vision by switching to black and white with NIR. They can also take extra time, which the human eye generally cannot do.