From what I've gathered from some (admittedly not in depth) research, the effective contrast of ink on paper for books tends to be around 12:1, and for long for

From what I've gathered from some (admittedly not in depth) research, the effective contrast of ink on paper for books tends to be around 12:1, and for long form text that tends to be what I shoot for. I find the as-high-as-you-can go contrast of pure black on pure white to be a (tiny) bit of a strain when I'm reading a sufficiently long article. I see these "all the text on the web is a sea of grey" articles come up every so often, and I agree that the kind of bananas low contrast sites that they point to are problematic. But when I look around, these honestly seem to be outliers. Sites like the New York Times, Washington Post, The AV Club, CNN, and so on tend to be in that 12:1 contrast range or even higher. There are exceptions--Vox is only around 7.5:1 contrast ratio (which surprised me, since I find it pretty readable, but they're using big text in a highly legible typeface). But the worst offenders I find often seem to be sites that I suspect are driven more by engineering departments than designers: Google App Engine and Apple's system documentation are the big examples in this article, for instance. (Apple's consumer-facing web sites tend toward noticeably higher contrast type than the linked fiasco.)