[pstricks] convert pstricks images into pdf

[Henry Proudhon]

Dear users,

maybe it's a stupid questions but i cannot handle it despite my efforts

I've plenty of eps files generaed with pstricks and I want to use them 
in a slide presentation with the beamer package and pdflaex.
I thus want to convert them into pdf images but when i do it (either 
with ghostscript or ps2pdf) it give me a paper sized image with large 
white margins.
Is there a way to avoid those margins (an option for ps2pdf) ?
if not what is the way to remove them ? I heard about pdfcrop but is it 
the best way ?

many thanks to your answers

henry