Semi-transparent text in beamer (pdflatex)

Question

I want to have some text appear semi-transparent, but not in an overlay fashion (where it eventually becomes solid) just permanently semi-transparent. To complicate matters, the text in question is part of a matrix:

$
\begin{matrix}
          & \{-2,3,5,0,8\} & \\
    \{-2,3,5,0\} & & \{-2,3,5,8\} \\
          & \{-2,3,5\} &
\end{matrix}
$

I want the third line in the matrix to be semi-transparent. Is there a way to do this?

Answer 1

Edit: improved the solution by turning it into a command with an optional argument.

Okay, discovered how to do it:

\newcommand{\semitransp}[2][35]{\color{fg!#1}#2}

...

$
\begin{matrix}
       & \{-2,3,5,0,8\} & \\
    \{-2,3,5,0\} & & \{-2,3,5,8\} \\
      & \semitransp{\{-2,3,5\}} &
\end{matrix}
$

The optional parameter controls the transparency. So \semitransp[20]{text} is lighter, and \semitransp[60]{text} is heavier. The default value 35 looks good on my computer screen. It is yet to be seen how it looks projected on a wall.