‘How do I change the brush size?’
The Quick Way – Hold down the b Key and draw the size brush you want
If you are using a Wacom pen, you can adjust the current eraser preset’s brush size by using the b hotkey as described above with the eraser tip of the pen. Using the normal drawing tip end of the pen with the b hotkey will adjust the current active paint synthesizer preset the same as if you were using a mouse.
Let’s work with the Preset called Acrylic Transparent which is in Manual Painting Category and General Examples Collection.
If you now hold down the b hotkey you can interactively resize the source brush in the main draw canvas as shown below.
The length of the dashed line you are drawing out with the mouse will be the new source brush size.
If you toggle to the Editor and Choose Brush Source and then hold down the b key and draw on the canvas you can see the Horz and Vert size change.
If the brush is made with an image you will see the IB Scale change
The actual brush size you end up painting with is a function of several different parameters in the Paint Synthesizer.
The source brush size is a maximum brush size that can then be modulated manually or interactively depending on the parameters specified in the Brush Modulation control panel. So the final sizing of the brush when you draw is a function of 2 different control panels, Brush Source and Brush Modulation, as well as potentially how you use an interactive modulator like pen pressure or tilt when you are drawing.
The Acrylic Transparent preset (from above) is using Path Pressure as a size Modulator.
The brush size is being modulated by the path pressure from 0 to 100%. This was done drawing with the mouse, and since the mouse doesn’t have interactive pressure modulation it is defaulting to 50% modulation. If you use a pressure sensitive pen and tablet to draw as shown in the example below note that the maximum brush size when you press the hardest is now matching the maximum size specified for the source brush above.
When the modulator is turned off the brush size is larger
There are lots of different modulators you play with.