Crop Marks too long when exporting with pdf 1.6 and Large artwork size

When i export a file in Illustrator that is made with the meter scale, large artwork size, and then i export the pdf, my crop marks are 10cm long wich uses too much space for nothing. 

I have to recreate an artwork with mm and export it with lower version of pdf to make it work...

I would prefer to make it work with the latest version of pdf to work faster.

Thanks