This thread is for people that want to read PDF files with the Amazon Kindle.
Even if unprotected PDF files are fully supported by the Kindle, there is a very annoying issue: these files are shown in full page. So, if you have a pdf file formatted for an A4 page, reading it in Kindle is impossible because character is shown too little.
Even if is possible to zoom pages, browsing these files is very uncomfortable, because only a small portion of the page is shown and the user is forced to use the joystick to move the magnification glass over the page.
So, the only solution is to convert PDF to another format. The best option is to convert it to .TXT files.
To convert files I suggest the freeware and open-source software calibre.
Even if calibre supports the native format of Kindle, I tried to do a conversion but the kindle is not able to read the converted file. Only the .TXT file was readable. I'll run some more tests, just to be sure that it wasn't my fault because there is a ton of settings in that software, so maybe I set something wrong.
However, currently, in my opinion plain text is the best option to read books with Kindle