Use nginx as proxy with cache for satic files

[ice-egal at web.de]

Hi,

I want to use nginx as a reverse proxy to my backend server with a cache 
for the static files.
Proxy and cache work perfectly, when I do it like this:

location / {
   proxy_pass http://backend.server.org/;
   proxy_cache cache;
   proxy_cache_valid 200 10m;
}


However I don't want to cache all the requests, only the requests on my 
images folder.
So I tried this:

location / {
   proxy_pass http://backend.server.org/;
}
location /images/ {
   proxy_cache cache;
   proxy_cache_valid 200 10m;
}

But now the image requests don't go through the proxy anymore, resulting 
in a 404 error. Is there any way to inherit the proxy settings from the 
parent folder/a certain location?
Of course I could just add the proxy settings to the "location /images/" 
block, but the images folder is not the only one I want to be cached, so 
there has to be an easier way to do this.

In other words: I want all requests going through the proxy, but keep a 
cache of ceartain folders on the nginx server. What is the best way to 
do so?

Thanks for reading, I hope someone is able to help me.

Regards
Alfred