Open full image straight from featured blog thumbnail

Hello

This request for help concerns the following site:
http://www.alanturnerimages.com/

Essentially I’m trying to open up the thumbnails straight from the blog list as large images.

I insert the images into the post as ‘Featured Images’.

At the moment when you click on the thumbnail it opens the actual post. Then when you click on the image it opens up fully using “prettyPhoto” (I can supply the code if needed).

Ideally I want to do that straight from the blog list and not the individual post.

Hope the above makes sense?

Cheers!