This has been discussed a few times, and the thread here
https://www.mobileread.com/forums/showthread.php?t=98618
has a guide on one method of changing fonts in the Sony's. I've used the Boroda hack instead.
More info here
https://www.mobileread.com/forums/sho...ht=Boroda+hack
All this mainly due to the Sony fonts being rather rubbish... and to compound the idiocy of designing an ereader with poor fonts, Sony also have ridiculous font sizes when choosing 'small' or 'medium' etc.
So, I've attached two PDF documents. One is for a 5" eink screen (PRS350/ 300), and one for the 6" screen (PRS650/505).
Each contains the same text, repeated in different fonts on separate pages (view using the default 's' size).
Download the size you need and transfer to your ereader.
Fonts I used for comparison are:-
Fontin, Joanna, Charis SIL, Droid Serif, Times New Roman, Georgia, Lucida Bright, Gill Sans, Helvetica.
I tried to keep text size as similar as possible and some fonts have extra page in a different size... Note that using the zoom to go to 'm' or 'l' etc won't be much use as the PDF doesn't reflow too well - instead :-
Use whichever of the attached two .doc Word files to change the font size and/or font to try out whatever you like. Then 'print to PDF' with the required page size (6" i use 9.1 x 12.3cm, 5" i use 7.6 x 10.1cm).
This is an easy way of testing fonts and getting the font size you like - without first needing to do any hack or epub CSS work. Then, once you've experimented and decided you do need to 'fix' your Sony you have a good idea of what font and the point size that will allow you to view it comfortably at the 'normal' small Sony display size.
It's also worth taking some trouble to format the line spacing and paragraph spacing - these PDF's have 2pt extra in between each paragraph. Most line spacing is single, but Charis SIL for example gave a huge space between lines with that setting and so is set at 'exactly' 12pt (for a 10pt font size).
Hope it's helpful - and others post examples with other favourite fonts!
You can see the difference it makes immediately, comparing 'Fontin' to the next page 'Joanna'. Joanna may well look very attractive on printed paper, but due to the lighter line weight it does not work so well on eink (for me). Droid Serif is clear but the x-height (?) is not to my liking...
I used Gill Sans for some time when I made PDF's of some books - far more attractive than Helvetica (or Arial), and comes installed on a Mac.
Coops