I have been taught that when using bolder weights of the same font next to lighter ones, the bolder one has to be enlarged very slightly, otherwise it'll look smaller. I've always wondered if that effect couldn't be offset [more] within the font itself.
It was a big "aha" effect when I realized that many fonts raise the x-line slightly in darker weights, to optically compensate for the smaller counters (and thereby the impression of the glyphs being smaller in toto), which seems to go a long way in offsetting the difference in apparent size.
1) Is it safe to assume that at least for text fonts, raising the x-line in the Bolds is a common practice? Considering those that don't do it (like say Palatino): What are reasons against it?
2) Why is, in some fonts, only the x-line raised, but not the ascender line [or even more rarely, cap line raised or descender line lowered]? Wouldn't the optical effect be comparable for them?
3) And what about the BASELINE* itself – could/should it also be shifted downwards slightly in dark weights, to "enlarge" the x-height region from both sides so to speak? – The only font I found that does this is Miso (its shifting baseline was briefly discussed here: http://typophile.com/node/17159#comment-115945 )
Curious as always for any opinions/comments/insights. Cheers.
[* Sorry fixed this, brain was tangled up]