1. PDF overview, pros and cons
Most eBooks are saved in common eBook file formats, like epub. Those eBooks are most often normal story books with text and maybe some images. You can change the font size and the reader resizes everything automatically and optimizes it to fit on the eReader screen. It would be idiotic to convert such a book to a PDF format.
The PDF file format is used for other things. Maybe you want to read a science book on your eReader, containing equations, mathematical expressions, chemical reactions, then the PDF format is the way to go. Such books have a strict layout and itís impossible to convert such a book to an ePub format. Equations arenít supported by normal fonts, so it just wonít work.
Some online sites (like Nature) also publish their articles in the PDF format. To view them, you need a PDF viewer on the eReader and have to deal with the advantages but also disadvantages of the PDF file format.
As already said, the big advantage is that a PDF file and thus a Viewer can display anything! Itís not limited to text or images, it can contain anything you can imagine. It can contain pixel based images (bitmaps), but also vector based images (you can zoom in without a quality loss), and also text and whatever other stuff. Thatís a big problem for eReaders because you canít just remove the layout and fit it on the relative small screen.
Displaying anything means such PDF files have custom layouts, maybe like newspapers or some science books with two or more columns. So changing the font size wonít work as easy as on ePubs because it will destroy the whole layout and thus create a huge mess, most often.
My Usage Scenarios
- Reading news articles in the bus or train which Iíve downloaded to the eReader in the morning
- Reading science books published as PDF or scanned and converted to PDF
- Reading lecture scripts published by my prof (I donít want to carry 600 pages around ^^) or created by other students with LaTeX in the lectures (always up to date and if some errors got fixed, I donít have to print it again)
- Reading exercise sheets, so I donít have to print them.