Photographing people and publishing the images is only very vaguely regulated.
Can I Shoot Footage in Public without Consent?
Yes, you can almost without restrictions shoot anything as long as what you're seeing is visible from public property.
There allegedly are laws protecting the sancticity of the home, but we could so far not find a clear source.
Can I publish Photos taken of Strangers without Consent?
Yes, if they are not the primary subject and the photo does show them in an inappropriate or vulnerable position. If they are a figure of public interest, like a politician or celebrity, the consent before publishing is not required.
Can I use Street Photos commercially?
Commercial use follows the same rules as non-commercial use, unless it is promotional (in advertisement or similar). For promotional use, consent is required.
Everyone has the freedom of expression. Freedom of expression entails the right to express, disseminate and receiveinformation, opinions and other communications without prior prevention by anyone. More detailed provisions on the exercise of the freedom of expression are laid down by an Act. Provisions on restrictions relating to pictorialprogrammes that are necessary for the protection of children may be laid down by an Act.
Source: The Constitution of Finland11 June 1999(731/1999, amendments up to 817/2018included)