I have a document with .5cm margins; I want to include a long image which will span the width of the page, ignoring margins. I don't care about the whole image being visible (or which part of the image is visible, to be honest) so long as it spans the width. At present the image goes off the right-hand side of the page but its left edge is aligned to the margin.
\documentclass[a5paper,twoside]{article}
\usepackage{graphicx}
\usepackage[a5paper,margin=0.7in]{geometry}
\begin{document}
\newgeometry{margin=.5cm} %tiny margins
Text here.
\vfill
\begin{center}
\hspace{-1cm} \includegraphics[height=4cm]{image}
\end{center}
\vfill
Some text here (not very much).
\end{document}
Bonus question: it would also be very helpful if someone could explain how to position the image a set distance from the base of the page, as opposed to just using \vfills to space things out.

\hspace*{-whatever}the*form prevents space being discarded at start of line but a negative hspace after the image as well (and dont put a word space between the\hspaceand the `\includegraphics. – David Carlisle Oct 22 '13 at 21:04