Apple’s developer release of its grotesque sans-serif font family “San Francisco” is generating discussions, including: its replacement of Helvetica and comparisons to Helvetica; Helvetica’s replacement of Lucida as Apple’s OS X UI fonts two years ago; comparisons of Lucida to Helvetica.
These raise bigger questions of legibility of Grotesque sans-serifs (the genre that includes Helvetica and San Francisco) versus Humanist sans-serifs (the genre that includes Lucida and Frutiger).
Here are references to on-line articles, blogs, and research papers on these subjects.
Apple release of San Francisco fonts to developers
http://appleinsider.com/articles/15/06/12/apple-releases-san-francisco-system-fonts-for-ios-os-x-and-watchos-2-to-developers
Apple video introduction of San Francisco fonts:
https://developer.apple.com/videos/wwdc/2015/?id=804
San Francisco in Apple Watch:
https://developer.apple.com/watch/human-interface-guidelines/specifications/#typography
Comparison of San Francisco to Helvetica
Article in German but Chrome’s German-English translator works well. Be sure to take the revealing Helvetica vs. San Francisco test at end of article; needs no translation, only discerning eyes.
http://kosmos.welt.de/2015/06/helvetica-vs-san-francisco-sehen-sie-den-unterschied-bei-apples-neuer-schrift/
Comparison of Humanist Lucida to Grotesque styles for legibility
Bigelow & Holmes on Lucida as the first new font family designed for digital displays and printers, and the merits of humanist style versus grotesque style for legibility:
http://bigelowandholmes.typepad.com/bigelow-holmes/how-and-why-lucida/
Samples of Lucida Grande
http://lucidafonts.com/fonts/family/lucida-grande
http://lucidafonts.com/fonts/family/lucida-grande/samples
Bigelow & Holmes on differences between Lucida and Helvetica (also relevant to San Francisco as a grotesque style like Helvetica):
http://bigelowandholmes.typepad.com/bigelow-holmes/2014/11/whats-the-difference-between-lucida-grande-and-helvetica-neue.html
Research finding that a humanist style sans-serif is more legible than a “square” grotesque sans-serif
“Assessing the impact of typeface design in a text-rich automotive user interface,” by Bryan Reimer at alii
http://www.tandfonline.com/doi/pdf/10.1080/00140139.2014.940000
http://dx.doi.org/10.1080/00140139.2014.940000
An earlier report on the same study:
http://www.researchgate.net/profile/Bruce_Mehler/publication/264439455_An_Evaluation_of_Typeface_Design_in_a_Text-Rich_Automotive_User_Interface_(Original_Manuscript_)/links/53df945b0cf2a768e49bb08b.pdf
Syntax
To our knowledge, the earliest scholarly design treatise on humanist versus grotesque and legibility is Erich Schulz-Anker’s brilliant and influential article “Syntax-Antiqua, a Sans Serif on a New Basis” (also in French: “Le Syntax Romain, un Linéale sur une base nouvelle” and German: "Syntax-Antiqua, eine serifenlose Linearschrift auf neuer Basis”), reprinted by the Stempel type foundry in 1970, from Novum Gebrauchsgraphik 7/1970. An earlier version published by the D. Stempel Foundry in 1969, in German only, is “Formanalyse und Dokumentation einer serifenlosen Linearschrift auf neuer Basis: Syntax-Antiqua”. Note that the concepts are based on Hans Ed. Meier’s design of Syntax, see also:
http://bigelowandholmes.typepad.com/bigelow-holmes/2014/07/remembering-hans-ed-meier-designer-of-syntax-antiqua.html
Related discussion of humanist "Droid" fonts versus grotesque "Roboto" fonts in Android
http://typography-daily.com/blog/2011/10/19/the-roboto-controversy/
http://typographica.org/on-typography/roboto-typeface-is-a-four-headed-frankenstein/
http://www.fastcodesign.com/3033126/roboto-rebooted-why-google-plans-to-update-its-font-like-the-rest-of-its-products