Since you are loading the caption
package, you could use \captiosetup{list=no}
:
\documentclass{memoir}
\usepackage[english]{babel}
\usepackage[demo]{graphicx}
\usepackage{caption}%This is necessary in order to ignore lof
\begin{document}
\listoffigures\clearpage
\begin{figure}
\captionsetup{list=no}
\begin{sidecaption}{Main Caption}[fig:label]%does not appear in lof
\includegraphics[width=0.5\textwidth]{Picture}
\end{sidecaption}
\end{figure}
\begin{figure}
\centering
\includegraphics[width=0.5\linewidth]{Picture}
\caption[]{Main caption} %does not appear in lof
\end{figure}
\end{document}
But using caption
with the memoir
document class produces a warning:
Class memoir Warning: You are using the caption package with the memoir class. This may cause unexpected or inconsistent results if you use any of memoir's captioning facilities.
This warning indicates that since caption
package is being used, memoir
's own caption configuration interface is not doing anything. If you want to keep memoir
's captioning facilities (without the caption
package), I'd suggest another approach, simply locally changing the file extension used for the figure(s):
\documentclass{memoir}
\usepackage[english]{babel}
\usepackage[demo]{graphicx}
\makeatletter
\newcommand\nocaptioninlist{\renewcommand\ext@figure{ll}}
\makeatother
\begin{document}
\listoffigures\clearpage
\begin{figure}
\nocaptioninlist
\begin{sidecaption}{Main Caption}[fig:label]%does not appear in lof
\includegraphics[width=0.5\textwidth]{Picture}
\end{sidecaption}
\end{figure}
\begin{figure}
\centering
\nocaptioninlist
\includegraphics[width=0.5\linewidth]{Picture}
\caption{Main caption} %does not appear in lof
\end{figure}
\end{document}
The demo
option for graphicx
simply replaces actual figures with black rectangles; do not use that option in your actual document.