For some time I've seen LaTeX-produced documents that had slight differences in fonts. When you looked at them, they had the same Computer-Modern or Latin-Modern, however, they looked more stylized (more lightweight).
By chance, and looking at another question here, I came across this document: http://dw.tug.org/pracjourn/2006-1/robertson/robertson.pdf in which I've seen clearly the difference, and has to do with optical size for a font at a given (output) point size. Here is a capture:
Look how the last line (even when they're all typeset at 12pt) looks with a more light font. I also noticed that in some Beamer documents using the sans-serif family (some had a more lightweight version of the font).
So the question is, without using XeTeX or LuaTeX (just plain LaTeX/pdfTeX), how can I get that lightweight (optical at 17pt) font for the size I want?
PD. I also noticed that there were some differences if one used tex->dvi->dvips->ps and pdflatex->pdf. In some .ps documents I've seen through the web, the fonts looked more lightweight by default. Maybe some TeX installations select those bigger optical sizes by default to obtain a more pleasing font rendering.