In an earlier post comparing OS Discoverer maps to open source OSM maps, I highlighted a crucial factor which may influence the decision to adopt one or other – the usefulness of various zoom levels, particularly noting the detrimental effect of zooming in too much, beyond a particular point. To show this in greater detail than my previous post, here are some screenshots, taken from the Garmin edge 800, showing every available zoom level.
The first image shows the basemap only. The first zoom level at which the OS Discoverer map appears is with the scale marker (top, centre) at 12 miles.
Notice also the difference between 500ft and 300ft,the point at which the POI levels appear (This is on the AUTO setting, and can be customised).