determine which image to use when sharing on facebook

Enable the 'Open Graph - Content' plugin. Then you can create an object in the JFBConnect backend > Objects area with the following settings:
- Name: any string
- Object Type: "article"
- Built-in FB Object: enabled
- Published: enabled
- Select a category: root of the articles that you want with this image
- Image Type: Article Intro Image or Article Full Image.

After you make the above changes, you'll have to manually re-scrape the pages with the FB Sharing Debugger to see if the new Open Graph tags have been set correctly.

It should be as simple as that, but let us know if you run into any issues getting it set up.

-Melissa

- what 'type' shall I set? 'image' seems not to be good: nimb.ws/VFw5GA

(Type should be "article". For future reference, Facebook has a full list of available object and action types here . Then in the right column, there's an "Image Type" - you still have this set to "First Article Image". Please change that value to article intro or article full image.

How comes?
What can I do to always have the whole image (first example)?

Facebook determines the best way to generate the share preview based on the image size. The recommended sizes for sharing can be found here .

For large image previews:

Use images that are at least 1200 x 630 pixels for the best display on high resolution devices. At the minimum, you should use images that are 600 x 315 pixels to display link page posts with larger images. Images can be up to 8MB in size.

For small image previews:

If your image is smaller than 600 x 315 px, it will still display in the link page post, but the size will be much smaller.

In the case where your image is smaller in the preview, the image size is 411px x 275px. So you'll need to make the image bigger for FB to generate a bigger preview.

-Melissa

JFBConnect is smart enough to always try and get an image. We'll try to use the preference you have set (first image in article) first, but if that can't be found, we go in the following order:
* Article Intro Image
* First image in the article
* Category Intro image
* First image in the category description

As for the image size, aspect and cropping, from the recommendations guide you linked to, please note:

We've also redesigned link page posts so that the aspect ratio for images is the same across desktop and mobile News Feed. Try to keep your images as close to 1.91:1 aspect ratio as possible to display the full image in News Feed without any cropping.

We can't control what or how Facebook may alter your image to display in a feed. The image in your post is 411x275, which has an aspect ratio of ~1.5:1. Because of that, it seems like Facebook is cropping the image.

I hope that helps explain things, but should you need anything else, let us know.

Thanks,
Alex