Do certain display types cause eyestrain? The answer is here:
http://bits.blogs.nytimes.com/2010/0...se-eye-strain/
Yes and no. It's not just the display quality, which some try to characterize in terms of contrast ratio and dot pitch. It can also be the way that fonts are rendered and pages are flowed. Right now, the epub documents look acceptable on the iPad. The pdf files are a tossup. Safari is the best pdf reader, but it is essentially limited to files you can browse. You cannot, afaik, shove in a url like file:///hamlet.pdf. Apple, in their finite wisdom, created all sorts of barriers between applications. Although it can pull in big external pdf files, Goodreader does not seem to have sophisticated flow control. The game is still early, and maybe someone will goad the Apple developers to improve the pdf readers. For novels in pdf form, I'm sticking to the e-ink eReaders until the iPad gives me something more reasonable.