Facebook link different than page URL

When I use the “Share on Facebook” button to share a link of an image from the image page view, the resulting link is different than the actual URL.

For example, the page I’m linking from is: http://www.martoshoffmanimages.com/stock-images/soulsticerace2014#gallery/1163/186

The resulting, broken, link that is generated on the target Facebook page is: http://www.martoshoffmanimages.com/blog/stock-images/soulsticerace2014/#gallery/1163/186

Using Version 2.0.66.29 of Nextgen Gallery Pro

Thanks in advance for your help.