I just noticed that Facebook has been changed on retrieving the picture url from feed. Usually I replace _s with _n and I get the "normal" image.
Now I get somthings like this:
which is only "small". How can I get the bigger one?
You should ideally be using graph api to get pictures. If however, you need to get bigger image from these type of url links. First retreive their final url after 302 redirect :
Remove the bold part, and you will get the original image:
EDIT : This method does not work anymore,graph api is the best way to go.