beamerfonts
A standard document (e.g. scrreprt) uses roman font family for text and Sansserif font family for titles etc. It is the other way round in beamer. How can I switch the two font families? Or why do beamer define the font families in this way?
For the background: I think this is my problem when using formulas, because they use the Sansserif font instead of the roman version. Formulas using the euler package look really poor.
P.S.: I compile with LuaLaTeX using TeXlive 2013.
Here's one possibility using pdfLaTeX; I choose Cyklop for the titles and Iwona for the regular text; I didn't use the originally requested Malvern font since the Font Catalogue warns:
The package as it is on CTAN is based on a LaTeX2.09 installation. Some support for LaTeX2e is available, though buggy.
Basically waht you do is to set the apropriate font for the elements using \setbeamerfont; for the regular text you have the normal text font, but another option is to change the sans-serif family used (as I did in my example).
The beamer manual can help you with the available fonts that are modifiable through \setbeamerfont. Ahother useful source could be the beamer appearance cheat sheet.
\documentclass{beamer}
\usetheme{CambridgeUS}
\usepackage[T1]{fontenc}
\usepackage{lipsum}
\setbeamerfont{title}{family=\fontfamily{cyklop}\selectfont}
\setbeamerfont{frametitle}{family=\fontfamily{cyklop}\selectfont}
\setbeamerfont{framesubtitle}{family=\fontfamily{cyklop}\selectfont}
\renewcommand{\sfdefault}{iwona}
\usefonttheme{professionalfonts}
\begin{document}
\begin{frame}
\frametitle{Test frame title}
\framesubtitle{Test frame subtitle}
\lipsum[4]
\end{frame}
\end{document}
Another options is to use XeLaTeX and appropriate fonts.
\usepackage{graphicx} and \usetheme{default} are superfluous
with \AtBeginDocument{\ECFAugie} you can change the font of the normal text
\setbeamerfont{my frametitle}{series=\ECFAugie} should be \setbeamerfont{frametitle}{series=\ECFAugie}
\framesubtitle{A researcher's perspective} does not have any effect in the preamble, did you mean \subtitle{A researcher's perspective}?
Things like
\newcommand{\bi}{\begin{itemize}}
\newcommand{\ei}{\end{itemize}}
\newcommand{\ig}{\includegraphics}
are not a good idea - they just obfuscater your code and makes it harder to read for anybody but you. You'll also loose functionality. If you want to save time, use an editor with auto complete and/or macros
\documentclass[12pt]{beamer}
%\usepackage{graphicx}
\usepackage[T1]{fontenc}
\usepackage{emerald}
%\usetheme{default}
\setbeamerfont{frametitle}{series=\ECFAugie}
\setbeamerfont{framesubtitle}{series=\ECFAugie}
\setbeamerfont{title}{series=\ECFAugie}
\setbeamerfont{caption}{series=\ECFAugie}
\setbeamerfont{author}{series=\ECFAugie}
\setbeamerfont{institute}{series=\ECFAugie}
\setbeamerfont{date}{series=\ECFAugie}
\AtBeginDocument{\ECFAugie}
\title{Blockchain: Traceability, Provenance and Applications for My Unknown Institute}
\subtitle{A researcher's perspective}
\author{John Doe}
\institute{Unknown Institute}
\begin{document}
\begin{frame}
\titlepage
\end{frame}
\begin{frame}
\frametitle{What is a Blockchain}
A distributed data structure which is
\begin{enumerate}
\item very difficult to tamper with
\item if tampered with, the tampering is easy to spot
\end{enumerate}
And who invented it?
\end{frame}
\end{document}
Please consider carefully for which occasions you use such a font.
Best Answer
The font families you use are usually set up by your beamer theme, the default being to use sans-serif everywhere. About the "why", it seems that sans-serif fonts prove easier to read on low-resolution projectors, but that's less of a problem nowadays, with more and more conference rooms equipped with modern hardware.
There are several ways you can change the fonts you use in a beamer presentation, only with latex. LuaLatex adds some features for loading TTF fonts and such, but that's probably more complicated than what you need here.
The easiest way is to use beamer font themes.
You can also change the font family (and more) for every beamer template, with commands like (example taken in the manual):
You can refer to section 18 (Fonts) of the beamer userguide for more details and examples, and to section 5.6 (Choosing Appropriate Fonts and Font Attributes) for basic advice about fonts in presentations.