[wallcraft]

PDF is a format for controlling exactly how text is displayed on the page. Usually the "page" is from a printed book or an A4/letter page sized document. If you try viewing a PDF on a PC, what you see is the actual page and a "zoom" just magnifies the page (perhaps only showing part of the page on the screen). EInk does not zoom and pan very efficiently, because of the time it takes to refresh the screen. What the Kindle does is show the full page either in portrait or landscape mode. In the latter case the margins are removed to give a bit more magnification, but there are only the two views of each page available. This works reasonably well on the Kindle DX but is not as good on the Kindle 2.

The alternative is to extract the text (and images) from the page and try to "reflow" them, i.e. change the font size and also change how the text appears on the page. Most other 6" EInk Readers (e.g. the Sony Readers, and several others all using mobile Adobe Digital Editions) include reflow options in addition to the full page options available on the Kindles. Reflow does not always work, but it can make some PDFs usable on a 6" screen.

Amazon is using mobile Adobe Digital Editions to display PDFs, but they have not implemented its reflow mode for native PDFs. What they have instead is the email-based PDF to MOBI (AZW) conversion that was the original way the Kindle 2 implemented PDF viewing. This is reflowing the PDF, but using a server rather than the Kindle to do the processing. The advantage of this method is that in principle a better reflow can be done off-line, but the disadvantage is that you don't get to see the original PDF pages. Note that there are other off-line reflow options: Calibre can convert PDF to MOBI for example.

PDFs formatted for a small page (or for large print on a standard page) will work well using the native PDF option on a Kindle 2. Otherwise, the PDF to MOBI method may be a better option.