It’s proved impossible for me to re-create the lenses used as clues in the parts of this series that have been “muggled”, and it seems that the only solution is to dis-assemble and archive the entire series. The bonus cache (#5) will remain available until March 2016 for anybody who’s solved the puzzle but hasn’t yet found it.
Dan Q archived GC54F78 Oxford Steganography #1 – Open In New Tab
This checkin to GC54F78 Oxford Steganography #1 - Open In New Tab reflects a geocaching.com log entry. See more of Dan's cache logs.