# Deformed drawings in loglogaxis

I constructed a graph by means of a loglogaxis with

xmin=5e0,
xmax=1e4,
ymin=1e-16,
ymax=1e0


and am trying to make an annotation by means of a circle. For this, I use

\draw[color=red] (axis cs:4e2,1e-12) circle (1);


. Unfortunately, I do not get a circle but an ellipse. I guess the \draw command is using the logarithmic axes for the radius in some way.

I just want a simple 'normal' circle for my annotation. How do I do this in the loglogaxis?

MWE:

\documentclass{standalone}
\usepackage{pgfplots}
\begin{document}
\begin{tikzpicture}
\begin{loglogaxis}
[
xmin=5e0,
xmax=1e4,
ymin=1e-16,
ymax=1e0
]
{
20 1e-12
700 1e-9
6000 1e-3
};
\draw[color=red] (axis cs:4e2,1e-12) circle (1);
\end{loglogaxis}
\end{tikzpicture}
\end{document}

-
Could you please post a complete MWE so I can play with an idea I had and see if it works? – JLDiaz Jun 16 '14 at 8:53

The trick is to use absolute units for the circle radius:

\documentclass{standalone}
\usepackage{pgfplots}

\begin{document}
\begin{tikzpicture}
\begin{loglogaxis}[
xmin=5e0,
xmax=1e4,
ymin=1e-16,
ymax=1e0
]