Nice clams!
I think I mentioned in the podcast about the need for extreme depth of field for SPS macros... thought I'd mention same applies for clams, for similar reasons. Here's an example of a clam shot I took where I really wish I had added a couple stops of aperture... but still a shot I like quite a bit.
http://www.reef-life.com/galleries/i....php?image=436
Another example, close but no cigar.
http://www.reef-life.com/galleries/i....php?image=435
