[msl]

No you can't. Only a licensed photography studio can do it [1]. You can, however, submit a paper photograph taken by anyone.

[1] https://www.poliisi.fi/passport/passport_photo_instructions

[emilfihlman]

I literally can. Please don't spread misinformation when I doubt you even are a Finn.

https://lupakuvienvastaanotto.fi/Default.aspx

E: not to mention that the page you linked doesn't even say anything about prohibiting self taken photos.

[tincholio]

You can register as a photographer very easily. I've been doing my own pics for years now.

[emilfihlman]

You don't even need to register as a photographer (to submit other people's photos). You can do it as an individual just fine, as the submission page directly mentions.