I only occasionally use the Fixed Zoom In/Out buttons on the Tools toolbar of ArcMap and had always assumed that they zoomed in/out by a set scale factor.
However, using ArcGIS for Desktop 10.2, I just set my scale to be 1:10,000,000 and then hit the Fixed Zoom In button 10 times while recording the subsequent scale each time and was surprised to see:
10,000,000 8,000,000 6,000,000 5,000,000 4,000,000 3,000,000 2,500,000 2,000,000 1,500,000 1,250,000 1,000,000
Dividing each scale denominator by its successor shows a sequence of: 1.25, 1.33, 1.2, 1.25, 1.33, 1.2, 1.25, 1.33, 1.2
Curious about what happened in between the scales above I experimented a little to discover that the first issuance of the Fixed Zoom In button simply takes the scale to the first of those listed above and then starts following the same pattern. Try starting with 1:8,000,001 to see ...
8,000,001 8,000,000 6,000,000 5,000,000 4,000,000 3,000,000
This seems like quite a neat solution, but not one that I had realised was in place - does anyone know if it has been documented anywhere?
I've looked in the Online Help without success.
In answer to @DevdataTengshe, the scales currently in my available list (see below) seem to bear no relation to those used by Fixed Zoom In/Out.
However, when I add 1:7,500,000 into my available list it does seem to insert that as an additional scale step ...
10,000,000 8,000,000 7,500,000 6,000,000 5,000,000 4,000,000
This makes the algorithm being used even more mysterious to me.