reducing the size of crop marks as per requirement--how to do it?

\documentclass[twoside]{article}
\usepackage{geometry}
\geometry{a5paper}
\usepackage[center,a4,cross]{crop}
\usepackage{blindtext}
\begin{document}
\Blinddocument
\end{document}


There are a few steps to modify the crop marks: define a smaller cross, define a crop mode, and apply the newly defined mode. The basic definition of the cross can be found in the manual of the crop package (page 16). It is a picture environment with two lines that each have a point of origin (x,y), an orientation and a length. Here you need to adjust the length but also the points of origin to make sure that the lines start closer to the center of the cross (for a 1cm cross you need to start 0.5 units away instead of 2 units as in the original example, for a 2cm cross 1 unit away, etc).

MWE:

\documentclass[twoside]{article}
\usepackage{geometry}
\geometry{a5paper}
\usepackage[center,a4]{crop}
% define smaller 1cm cross
\newcommand*\smallcross{%
\begin{picture}(0,0)
\unitlength1cm\thinlines
\put(-0.5,0){\line(1,0){1}}
\put(0,-0.5){\line(0,1){1}}
\end{picture}%
}
% define crop mode with four crosses, one on each corner of the page
\cropdef\smallcross\smallcross\smallcross\smallcross{mycross}
\usepackage{blindtext}
\begin{document}
% apply the new crop mode
\crop[mycross]
\Blinddocument
\end{document}


Result: