And would it also be ok to take a picture of neatly written formulaes?
For many reasons (searching, indexing by search engines, screenreaders used by visually impaired users, exporting posts, ...) it is much better to include text as text rather than text as picture. At least you should try to make your question to be comprehensible without the picture.
I think there are some exceptions. For example:
- I would consider reasonable if you make a question self-contained but you add some some longer text as a picture, where readers can find more details (if they wish). But in many cases reference to a text (with a link - if available) would be sufficient in such situations.
- The community is much more tolerant to new users who are learning their way around the site. It is quite likely that some other users might help you and edit the post. Or at least direct you to some tools and information which might help you edit it yourself. But it is expected that users eventually, as they gain experience with the site, improve quality of their questions. Correct formatting and typesetting is one part of that.
- The questions where the OP has shown some effort to solve the problem by themselves are usually well received. If such attempt is shown even as a picture, the post is more likely to get a positive reaction than a post which contains MathJax, but is merely a copy of the homework assignment. If you browse a bit among the images posted on this site, you will certainly find a few with handwritten mathematics. And some of the were received quite well.
I have posted an answer partly because the OP asked me to. And partly because the older discussions I was able to find seem to be slightly different in the sense that this question asks about this issue from the viewpoint of the poster, while several older discussions are about what other users should do when they see questions containing text posted as pictures (or even consisting only of pictures).