I am a big fan of LibreOffice, because it is both free and powerful – powerful enough to give you complete access to all OpenType features. I am not sure whether optical sizes is something that is actually part of the OpenType specs, but I do know that good fonts come with at least two, usually preferably three optical sizes. The font of choice for me is EB Garamond.
Here is the problem: Anyone writing an historical or classical text, will want footnotes; these are usually set in a smaller font size (usually 10 points versus 12 points body text). However, I today realised that the font I am using is using the same optical font size for both 10-point and 12-point sized text, vz.:
Figure 1: Comparison of font shapes for EB Garamond for seven different point sizes. Image created by typing the sample letters in LibreOffice, then applying the different zoom levels to see the letters at the same on-screen size.
As the image demonstrates, the optical font size is exactly the same, irregardless of point size. I should mention that the reason I am expecting different optical sizes, is because the first iteration of the font (which only got developed to v. 0.16), included EB Garamond 12 and EB Garamond 08. The current iteration of the font is, as far as I know, a continuation of the work done by Georg Duffner. I would expect it to include at least two optical font sizes. I do not have any software with which to inspect fonts, and so my only method is to make visual comparisons as above.
How can I access the different optical sizes of a font via its OpenType features? Given that LibreOffice simply uses the CSS tags to access them, this would apply both to web design and word processing. It could of course be that the current version of the font doesn’t include multiple optical sizes, but that is beyond my means to investigate. The font should choose the correct optical size for any given point size.
Note: I would suggest the new tag
optical-size, but I do not have enough reputation to do so.