see the new Proposal is #112 on the Difficulties filtering Variables
<https://github.com/xroche/httrack/issues/112>
But luckly copper mine keeps the order the same so we can fudge it.

So on to you issue

Base Page should be
www.ssoastro.org/coppermine/thumbnails.php?album=16

Rules should be
-*
+www.ssoastro.org/coppermine/thumbnails.php?album=16&page*
+www.ssoastro.org/coppermine/displayimage.php?album=16&pos=*
+www.ssoastro.org/coppermine/displayimage.php?pid=*&fullsize=1
+www.ssoastro.org/coppermine/albums/userpics/*
-www.ssoastro.org/coppermine/albums/userpics/*/thumb_*
-www.ssoastro.org/coppermine/albums/userpics/*/normal_*


So going from the Top:
 Block EVERY THING
 Allow all pages of the archive (this one is just 1 and 2)
 Allow each picture's page
 Allow the Sub window "Full size" page
 Allow the Actual image
 Block the Thumbnail version
 Block the Picture's page "Normal" version




Here are all three image version for the first picture. (on page 2)
albums/userpics/10001/thumb_600mm_Linear_2001_1.JPG
albums/userpics/10001/normal_600mm_Linear_2001_1.JPG
albums/userpics/10001/600mm_Linear_2001_1.JPG


This is a fairly simple filter, but I hope that helps with the understanding.
My run got 75 images from album 16