[SmartCrawl Pro] Smartcrawl Opengraph Images too small for Facebook

Hi There,
i need some help with the og:image function of smartcrawl. Smartcrawl uses by default the featured image for the og:image right? But facebook tells me, the og:image is too small. It looks like smartcrawl uses a very tiny thumbnail. Is there a way to change this WITHOUT adding an image to every Post manually.

Example:
https://developers.facebook.com/tools/debug/sharing/?q=https%3A%2F%2Fdocumentus.de%2F

Cheers,
Ben