Although this question has already been answered, I figured I'd add a little code I luckily figured out while combining two codes together to get the full result I was looking for.
So, I have a few transitional (code block) images on my site (http://www.goffcreative.com), specifically the subscription image where the button transitions colors.
I came across this answer while looking for a resolution for hover roll-overs on linked IMAGES and GALLERIES only, however even my coded transitional images (which I didn't want to change) were affected by this code.
Anyhow, super-long story a little shorter, if you ONLY want images and gallery images that are linked to have the hover effect, use this:
opacity: 0.6; filter: alpha(opacity=60); }
If you don't have any code block links (you don't want affected) on your site, this isn't necessary.
Thanks @jasonvb for the original! You're awesome.