metrics vs. optical spacingMetrics always; optical for emergencies

If you use Adobe In­De­sign—and if you don’t, you can ig­nore this page—you might have no­ticed the popup menu that gives you a choice be­tween “met­rics” and “op­ti­cal” font spacing.

De­spite the be­nign-sound­ing name, op­ti­cal spac­ing will man­gle your font. It is akin to putting your finest cash­mere sweater in the wash­ing ma­chine. So al­ways use the “met­rics” option.

This set­ting con­trols the way In­De­sign lays out your type:

In this type de­signer’s opin­ion, the spac­ing of a font—that is, the de­sign of the white spaces—is far more con­se­quen­tial to its ap­pear­ance than the de­sign of the black shapes. If you buy a pro­fes­sional font (see font rec­om­men­da­tions), and then run it through the op­ti­cal-spac­ing wringer, you’re throw­ing away most of what you paid for.

Still, don’t take my word for it. Com­pare these sam­ples, show­ing Eq­uity with met­rics spac­ing on top, and op­ti­cal spac­ing on the bottom:

The goal of spac­ing let­ters in a font is to give type­set text an even color, min­i­miz­ing dark and light spots. Op­ti­cal spac­ing does well enough with let­ters that are sym­met­ric—say, an up­per­case H or low­er­case n.

But those are easy. As we can see above, achiev­ing the same even­ness is harder with asym­met­ric let­ters like low­er­case a or r or t. But it’s also vi­tal, be­cause these let­ters oc­cur so fre­quently in text. This is why hu­mans out­per­form the ma­chine on font spacing.

“So what is op­ti­cal spac­ing good for?” Op­ti­cal is the emer­gency op­tion if you find your­self work­ing with:

  1. A font that has bad spac­ing (for in­stance, the client has in­sisted on such-and-such free fontor;

  2. A font that’s be­ing pressed into ser­vice be­yond its de­signed ca­pac­ity (for in­stance, a body-text font be­ing used for a headline).

If such an emer­gency arises, break the glass. Try op­ti­cal spac­ing. Judge with your eyes whether it helps.


by the way
  • Why do these spac­ing dif­fer­ences mat­ter more at small point sizes than large? Our eyes per­ceive light and dark dif­fer­ently as type reaches the lower limit of our abil­ity to de­tect vi­sual de­tail. See screen-read­ing con­sid­er­a­tions.

  • Abuse of op­ti­cal spac­ing is es­pe­cially pro­nounced among Amer­i­can book de­sign­ers. Mag­a­zine and news­pa­per de­sign­ers tend to use met­rics spac­ing. But this isn’t sur­pris­ing—books have smaller de­sign bud­gets, most of which is spent on the cover, not the interior.

  • I’ve tried to track down, so far fruit­lessly, the ori­gin of the “op­ti­cal spac­ing is bet­ter” cargo cult. For in­stance, was there a pop­u­lar graphic-de­sign book that first prop­a­gated the ur­ban leg­end, which then be­came en­trenched? (One graphic-de­signer col­league the­o­rized that Adobe train­ers spread the myth.) Con­tact me if you have clues to share.

  • Still, I blame Adobe for coin­ing the mis­lead­ing names “met­rics spac­ing” and “op­ti­cal spac­ing” in the first place. If these op­tions had been named ac­cu­rately—e.g., “orig­i­nal spac­ing” and “syn­thetic spac­ing”, or “nice spac­ing” and “shitty spac­ing”—In­De­sign users would likely have made bet­ter choices.

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