Conglog is a very good one for an evening visit, and quite a lot to photograph as you've seen :)
Go past the lake on the Wrysgan side past the Rhosydd chapel to the gate that is about level with the Conglog mill and Cwmorthin mine manager house - then head up towards the Rhosydd tips. The adit is about half way up on the left just below the track. It's quite easy to miss. You'll see some small open pits on the right, that's about the level where the adit is - just below the track.
Hope that made sense!
Adit is wet - but below welly depth these days (was a year ago at least) thanks as I understand it to Steve Turbo? :)
my orders are to sit here and watch the world go by