DOUBLET is the correct term for a cemented lens pair. In a DUPLET lens system there are two groups of lenses separated by a space, and successive lenses in each group are in contact; not cemented together. I wrote this article upon reading a few different books I have picked up over the past couple of years in an attempt to deepen my knowledge of photography and the means we use to the end of the photograph. I just hope everyone gets a little bit of 'I didn't know that' from this article as I have from reading the material that inspired it.

Oh, and the coin thing. Yeah, I misused the word. I was thinking 'To coin the phrase' and got tunnel visioned into the word coin. So, yeah, that was my bad. I hope you all will be understanding. Not like I've been accused of being confusing before. ;p