I tried a few times to achieve mirror-like images with water, like this:
However, I never manage to take out all the roughness due to waves, streams and so on. I guess these pictures aren't always taken with perfectly flat water, and that they use long exposures to smooth all the irregularities. Is that true?
How can I get a nice reflection even if the water is not perfectly still?
Little update: indeed it's just a matter of finding place where the water is very still :) A small capture from Norway, a few days ago:
Thank you very much for the advice!