Facebook Link Post is Cropping Image
When pasting a campaign URL into your Facebook fanpage post, Facebook crops your image.
In this example, the wineglasses are cropped so you don't see the entire wine glasses.
Facebook sizes link post images to 1200x628. There's no getting around that.
Solution #1 - Resize the image in your campaign to 1200x628
If a link post is the type of post you will use most frequently, you can edit your image in Photoshop or other photo editing software to resize it to 1200x628. This way you are giving Facebook the image size correctly for that post type.
If you update your campaign FB image and try the link again to create a FB link post and the image doesn't change, that's because Facebook caches the first image that you had when you used the link in your post. If you want to refresh the image, you'll need to use Facebook's tool to "Fetch new scrape information."
1) Edit your image so it's 1200x628
2) Update the campaign FB image
3) Save your campaign
4) Go to this URL
5) Enter your campaign URL
6) Click the "Fetch new scrape information" button
7) Go back to your fan page and try the campaign link again. You should see your newly sized image in the post.
Solution #2 - Change the Image in the Post
1) After entering your campaign URL, remove the image
2) Click the "+" sign and select an image from your computer. 700x700 works fine.
3) Click Publish
Your post should have an image that isn't cropped.