Setting optimum font size for Aluratek Libre

[PodPeople]

I have been bothered by the huge jump in font sizes between zoom levels 1 and 2 on the Aluratek Libre. On ePubs zoom 1 displays 31 lines of text and zoom level 2 displays 23 lines (using the serif font). I would like a font size in between these two. Here are the number of text lines for each zoom level:

Zoom 1 - 31
Zoom 2 - 23
Zoom 3 - 20
Zoom 4 - 18
Zoom 5 - 15
Zoom 6 - 11
Zoom 7 - 9

I played around with changing the base font size in Calibre. I found that if I set it to either 8 or 10 the number of lines of text per zoom level is as follows:

Zoom 1 - 42
Zoom 2 - 31
Zoom 3 - 26
Zoom 4 - 24
Zoom 5 - 20
Zoom 6 - 15
Zoom 7 - 12

Whereas before there was only one step between 31 lines per page and 20 lines per page (zoom levels 1 - 3), by setting the base font size to either 8 or 10 you get two steps (zoom levels 2 through 5). I think this gives a more optimal range for choosing font sizes.

I don't know whether this would work the same way on the Jetbook or Jetbook Lite -- they have different font size options.