thumbnails stretched

ok, I got the plugin to work but all my thumbnails are stretched so distorting the images. I’ve tried playing with the height but it just makes the images bigger and i think justifying them to the margins so still stretched. Can someone advise what I’m doing wrong? I wanted it to look like the plugin authors page http://miromannino.com/my-photos/ but just can’t get it to work like that with images made all to the same height, filling a row and cropped to fit.

Current code I have is [flickr_photostream images_height=”120″]
But as you can see doesnt work right https://www.simonparker.photos/gallery/

Anyone help me?