Hi Thomas,

please the following article when you have your next question: 
http://www.shlomifish.org/philosophy/computers/netiquette/email/start-new-thread.html
> Thomas Fehige <mailto:thomas@fehige.de>
> 6. Juni 2016 um 16:05
>
> In the fonts book I found the \definebodyfont command, but it does not 
> to do what I expected. What I need (for a poster) is a set of absolute 
> font sizes. I tried the code below. I put some quirks in, like the 
> huge value for "a", to see if it works, but it doesn't. It just uses 
> the preset proportions relative to the preceding fontsize command (in 
> the example, \tfx is bigger than \tf).
>
> \definebodyfontenvironment[palatino][24pt][
>
> text = 24pt,
>
> small = 22pt,
>
> x=22pt,
>
> scriptscript = 16pt,
>
> xx = 16pt,
>
> big=28pt,
>
> a = 80pt, % 28pt
>
> b = 40pt,
>
> c = 50pt,
>
> d = 50pt,
>
> interlinespace = 3ex,
>
> em = italic
>
> ]
>
> \setupbodyfont[palatino,24pt]
>
> \starttext
>
> \tf tf\\
>
> \tfa tfa\\
>
> \tfb tfb\\
>
> \tfx tfx\\
>
> \tfx tfx
>
> \stoptext
>
>
When you have only a small amount of text the use of 
\definebodyfontenvironment is overkill because you can use the 
\definedfont command to set a certain font size.

\starttext

\start \definedfont[Serif at 20pt]
\input ward
\stop

\startfont[SansBoldItalic at 18pt]
\input ward
\stopfont

\stoptext

Wolfgang