Q:

Smaller parskip than half for KOMA-Script?

I am using the documentclass scrbook. To mark paragraphs I need both vertical spacing and indentation.
I know that KOMA-Script supports the option parskip or halfparskip, however, this disables the indentation. In order to get it back I declared \setlength{\parindent}{1.5em} in the preamble.
Since I am using both vertical spacing and indentation, I would like to have even smaller spacing than halfparskip. Is it possible to get an even smaller parskip than half in KOMA-Script?

A:

You could use something like 
\setparsizes{1em}{0.25\baselineskip plus .25\baselineskip}{1em plus 1fil}. 

The first value is parindent, the second parskip, the third parfilskip. "half" uses 0.5 in the second argument.

