Float captions

[Dan Leggate]

I'm looking for a way of making my float captions separate from the main
text. I've used the caption package to give the captions an indent at both
margins which works quite well. The only thing is a lot of my figures also
have descriptions in standard text after the caption itself and this is hard
to tell apart from the rest of the text.

Is there any way I could create a "subcaption" environment which is like the
standard one except with, say, a 20pt indent on both margins?

Many thanks.
Dan