On Tuesday, 7 August 2018 09:59:04 UTC+2, Mike Collins wrote:

I thought the Russian images from 1975(?) were pretty good, given the
technology then. I don't know what the atmospheric extinction is, but
they can still image their immediate

The Venera 13 colour images show a horizon although there is some doubt
whether it is 100 metres away or a mirage.

Is the density and chemical makeup of Venus' atmosphere sufficient to cause noticeable refraction? I suppose if the visual sensor is totally immersed then it hardly matters. Only if they are looking in, or out of the toxic goldfish bowl would one enjoy the "stick in water" effect.