Vertical metrics strategy for optical sizes

Hello everyone, 

I'm experimenting with interpolation between a "caption" and a "display" optical size. I'm hesitating between two strategies regarding vertical metrics. First one is to keep the same x-height between both masters and only have the ascenders and descenders move around, second is to keep the same overall height and make everything change in between. See this quick sketch.

I'm leaning towards option 2, but I'm very curious to know your opinions on the matter. 

Thanks in advance for your help


  • Ray LarabieRay Larabie Posts: 1,379
    Do some tests at actual sizes and adjust them until you like the way it looks.
  • Alex VisiAlex Visi Posts: 185
    I think 2 is a more correct thing to do. Option 1 sort of changes the em in UPM and then the user will have to compensate that by using a smaller font size or taller line spacing and option 2 already includes that correction.
  • John HudsonJohn Hudson Posts: 2,973
    Option 2 is the usual method, and means that your optical size adjustments are relative to the em square height, which is what gets scaled to the nominal type size in an application. So when you increase type size from 10pt to 36pt, you generally want the relationship of extenders to the overall height to be pretty similar, and for just the proportions in between to change.
  • KP MawhoodKP Mawhood Posts: 294
    A little lost here. The consensus on a similar thread seems to be that it's better to set the x-height to normal (see Font with extremely tall ascenders/descenders). Whereas, here the current consensus is to reduce the x-height. 

    How is the advice for vertical metrics so different?
  • Mark SimonsonMark Simonson Posts: 1,654
    edited August 2021
    I think a better way to think of it, the size of the caps relative to the UPM should remain constant, while x-height and ascenders/descenders may vary for different optical sizes—within a family. The other thread was talking about such proportions relative to other unrelated fonts.
  • KP MawhoodKP Mawhood Posts: 294
    Got it. Thanks for taking the time to explain @""Mark Simonson"
  • Makes sense. Thank you all for your insights :) 
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