I am using Open Graph image tags for social sharing on my website. I have an image 1200px x 630px for Facebook marked up in an OG tag, however this looks real bad on Pinterest as they use portrait images. Problem is Pinterest use same OG tag as Facebook, so how do I force Pinterest to use a different (portrait) image?
There can be upto six og:image tags. Refer to the Article Pins
So when you add image for Facebook, you would like to specify as following og:image along with og:image:width (1200) and og:image:height (630)
Similarly, for Pinterest, specify another instance of og:image along with og:image:width and og:image:height.
The crawlers of Facebook and Pinterest will pick the best dimension as per their specifications.