Does Nginx really include charset maps

I'm using Linux Debian WheezY with PHP 5.5.1 and Nginx 1.6.2 and search for a solution to open files with german umlauts as, for example, "vögel.jpg" or files in directories with german umlauts, but it appears only the error 404 Not Found nginx/1.6.2.

If I type v%f6gel.jpg with f6 (ö ISO-8859-1 and ascii) instead of vögel.jpg it works and the file is shown in the Browserwindow.

If I type v%C3%B6gel.jpg with %C3%B6 (ö UTF-8) instead of vögel.jpg the filename jumps back in the url field to vögel.jpg and nothing is shown.

My Nginx settings are:
charset utf-8;
source_charset utf-8;
override_charset on;

charset and source_charset are determined according to the Nginx homepage to add the charset utf-8 to the “Content-Type” response header, however, I don't know if for jpg files is used a response header. If is used ascii or ISO-8859-1 or other charsets instead of utf-8 nothing changes.

Also if are included the nginx charset maps nothing changes:
include koi-utf;
include koi-win;
include win-utf;

Just so this seemingly not takes affect:
source_charset ascii;
charset utf-8;
override_charset on;
charset_map ascii utf-8 {
f6 c3b6;
}

or

charset_map iso-8859-1 utf-8 {
f6 c3b6;
}

or

charset_map utf-8 ascii {
c3b6 f6;
}
nginx error: invalid value "c3b6"

or

charset_map utf-8 iso-8859-1 {
c3b6 f6;
}
nginx error: invalid value "c3b6"


According to PHP with echo mb_detect_encoding($filename); the jpg file encoding is ascii, but if I change the file encoding to utf-8, the jpg files can't be opened in the browser and look like this: vögel.jpg

Everything stays always the same even without charset. Thus my question: Does Nginx really include charset maps and if yes, how must this happen so that files with umlauts can be opened in the browser.
Many thanks