Google has three methods of creating the description(SERP) for your site:
# If the meta description tag is set, it will use the description from here.
# If there is no meta description tag set, it will simply extract a portion of the text from your website (like it is doing now).
# There are some cases where you set meta description, and google will still choose to extract some text from your site, if it better suits the keywords in the given search. This is highly unlikely that will happen with any imagevue gallery.
In your case, I can see you have already set another description. May I ask when you did this? Google can take from 1 to 6 weeks to upgrade your SERP(description), and it only happens when googles searchbots re-index your website. The SERP that google is currently using, is inherited from an earlier version of your website before you customized it. You have correctly set your description meta tag, and most likely you just need to wait some time before google updates your SERP -
<meta name="description" content="Amos Chapple, award winning New Zealand photographer" />
You could extend that description with a few more words I may suggest, just because you can ...
Just for the record, to set the description tag in imagevue, you go to admin -> settings -> SEO.description ... Add your description here. However, in your case because you have made a custom index template, you are using the description that you have hardcoded ...
Beautiful gallery you have at
http://www.amoschapple.com/ btw ...