As best I'm aware, this is one of the more thorough descriptions of the Venera programs: http://mentallandscape.com/V_Venus.htm

Don Mitchell's web page has perhaps the highest quality images taken by the Venera probes. He gained access to the raw data from the probes and used his expertise with modern image processing tools to extract much better quality images.

This and this are great examples of his work. Quite something to see these, taken at the bottom of a ~460 °C, ~90 bar supercritical CO₂ ocean.

Edit: Oops, just saw /u/UmbralRaptor's comment, already referencing Mitchell's page. But I'll leave this one as I think it adds detail.

Is supercritical co2 optically clear like air?

Yes. Ben Krasnow has a good little video on making the fluid.

Wow cool. I always wondered why the venera pictures weren’t all foggy/cloudy but I knew Venus doesn’t have normal air

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