[Tex/LaTex] How to adjust spacing between caption and table / figure in beamer

Question

I want to adjust spacing between caption and table/figure in beamer. However I am not able to overcome the warning

Package caption Warning: \caption will not be redefined since it's
already (caption) redefined by a document class or package which is
(caption) unknown to the caption package.

I have tried by using caption and subfig packages. I used the command \captionsetup{skip=0pt,belowskip=0pt}. I am unable to overcome the warning. EDIT: I wish to add that I am trying to modify (reduce) the spacing in this frame. For other frames I am okay with the default spacing.

I need following format for my frame.

MWE the way it appears to me is

\documentclass{beamer}
\mode<presentation> {\usetheme{Madrid}}
\usepackage{graphicx} % Allows including images
\usepackage{booktabs} % Allows the use of \toprule, \midrule and \bottomrule in tables
\usepackage{lmodern}% http://ctan.org/pkg/lm
\usepackage{bm}
\usepackage{subfig}
%   \usepackage{caption}
\graphicspath{{Images/}} % path for images

\begin{document}
    \begin{frame}
    \frametitle{Results: Measurement of Length}
    \begin{picture}(0,200)
    \put(-5,210){
        \begin{minipage}[t]{0.48\linewidth}
            \setbeamerfont{caption}{size=\tiny} 
            \captionsetup[figure]{skip=0pt}%,belowskip=0pt}
            \begin{figure}
                \includegraphics[width=4.5cm, height=3cm]{C5.S.Results/Slide1.png} 
                \caption{Calibration: 1mm $\approx$\ 247 pixels.}
            \end{figure}
        \end{minipage}
    }
    \put(175,210){
        \begin{minipage}[t]{0.48\linewidth}
            \centering
            \tiny{
            \begin{table}[H]
            \setbeamerfont{caption}{size=\tiny} 
            \captionsetup{skip=0pt,belowskip=0pt}   
            \caption{Mean of measurements shown in Fig.\  1}
            \begin{tabular}{cc}
                \specialrule{1pt}{0pt}{3pt}
                \textbf{Reading} & \textbf{Measurements from } \\
                \textbf{Number}& \textbf{Fig. A \ ($\bm\mu$m)}  \\
                \specialrule{1.5pt}{2pt}{4pt}
                    1 & 121.6\\
                    2 & 117.6\\
                    3 & 121.6\\
                    4 & 137.8\\
                    5 & 121.6\\\specialrule{0.25pt}{2pt}{4pt}
                \textbf{Mean diameter :} & \textbf{124}\\
                \specialrule{1pt}{2pt}{2pt}
            \end{tabular}
            \end{table}
            }
        \end{minipage}
    }
\end{picture}
\end{frame}
\end{document} 

The frame comes out like this

Answer 1

The best way to proceed here is to locally redefine \abovecaptionskip and \belowcaptionskip (default value=7pt). The following example shows this redefinition (it's local since it's done inside an environment):

\documentclass{beamer}
\mode<presentation> {\usetheme{Madrid}}
\usepackage{graphicx} % Allows including images
\usepackage{booktabs} % Allows the use of \toprule, \midrule and \bottomrule in tables
\usepackage{lmodern}% http://ctan.org/pkg/lm
\usepackage{bm}

\setbeamertemplate{caption}[numbered]

\begin{document}

\begin{frame}
\frametitle{Results: Measurement of Length}
    \begin{picture}(0,200)
    \setlength\abovecaptionskip{-5pt}
    \setlength\belowcaptionskip{0pt}
    \put(-5,210){
        \begin{minipage}[t]{0.48\linewidth}
            \setbeamerfont{caption}{size=\tiny} 
            \begin{figure}
                \includegraphics[width=4.5cm, height=3cm]{example-image-a} 
                \caption{Calibration: 1mm $\approx$\ 247 pixels.}
                \label{fig:calibration}
            \end{figure}
        \end{minipage}
    }
    \put(175,200){
        \begin{minipage}[t]{0.48\linewidth}
            \centering
            \tiny{
            \begin{table}[H]
            \setbeamerfont{caption}{size=\tiny} 
            \caption{Mean of measurements shown in Fig.~\ref{fig:calibration}}
            \begin{tabular}{cc}
                \specialrule{1pt}{0pt}{3pt}
                \textbf{Reading} & \textbf{Measurements from } \\
                \textbf{Number}& \textbf{Fig. A \ ($\bm\mu$m)}  \\
                \specialrule{1.5pt}{2pt}{4pt}
                    1 & 121.6\\
                    2 & 117.6\\
                    3 & 121.6\\
                    4 & 137.8\\
                    5 & 121.6\\\specialrule{0.25pt}{2pt}{4pt}
                \textbf{Mean diameter :} & \textbf{124}\\
                \specialrule{1pt}{2pt}{2pt}
            \end{tabular}
            \end{table}
            }
        \end{minipage}
    }
\end{picture}
\end{frame}
\end{document}

The result:

It's better not to number objects manually for cross-references; the recommended way is to use the standard \label, \ref mechanism. In your figure I placed a \label:

\caption{Calibration: 1mm $\approx$\ 247 pixels.}
\label{fig:calibration}

and then, in the table, I used \ref

\caption{Mean of measurements shown in Fig.~\ref{fig:calibration}}

(two runs are needed for the cross-reference to appear). I added

\setbeamertemplate{caption}[numbered]

to the preamble, so figures and tables are explicitly numbered.