Can I change brush diameter without lifting pen [and independently of pressure]?

Have you tried the following keyboard shortcut? With the brush tool selected,  Ctrl + Option and drag left and right to change size or Ctrl + Option drag up and down to change softness or hardness?

the answer is yes. You'll need a program called AutoHotKey to do it. Go to their main site and download their software and install it.

Here is a simple AHK script which you will then run to acheive what you need:

$]::
send, {Lbutton up}
send, ]
send, {Lbutton down}

return

$[::
send, {Lbutton up}
send, [
send, {Lbutton down}

return

I recommend reading up on their tutorials on how to exactly run and install the software, and to also run scripts once it's installed. There is a learning curve with this software.

The above script will allow you to press [ or ] while your pen is held down on the tablet and the brush will resize without you having to lift the pen. I'm running the exact script right now and it works quite well.

I don't seem to be able to do that on a windows system when the Pen is in contact with the tablets surface keyboard key presses seem to be disabled or discarded. So the shortcut keys [ and ] do nothing tablet features that are set pass key strokes also do not work like the intuos touch ring set to [ and ] have no effect..

Message was edited by: JJMack

Have never installed a program like AutHotKey so I do not know if it will or will not will not work.  I may depend on where the keypress are being blocked or discarded. And how AutoHotKey stuff in a ketstroke.

AutoHotKey's capability seems unlimited. It lets you do things way above and beyond what Photoshop's default capabilities are.

The script posted above does indeed work as I use it regularly. AHK isn't without flaws though, there are glitches on occasion. Whether that has anything to do with AHK or the always-changing windows environment it's running under is another question.

You can assign unlimited functions to your right button, your middle button, your forward and back buttons... and to any key on the keyboard, and thats just for starters.

So in other words, your middle pen button can be set to pan your image in photoshop, but at the same time it can also rotate the canvas, switch tools, run .jsx scripts - it overcomes the limitations of Wacom's driver software (ie. middle button = pan/scroll only) so in other words middle button can do 10 different things whenever you want it to. Press it once to pan, press it twice to rotate, etc... or hold it down for 1 second to run a .jsx script, hold it down for two seconds to select the eraser tool, hold it down for 3 seconds to switch to fullscreen mode...and so on... it's unlimited.

Almost all my keyboard shortcuts are programmed into the pen/mouse buttons, so I don't even look at the keyboard while using photoshop anymore.

I tend to stay away from applications that do thing like autohotkey does. When I was younger and braver I wrote code that took over control of keystroke and other system interrupts.  What I most remember about that time in life are the countless number of times I crashed DOS before I got the code to work.....

I just tried setting shape dynamics to pen tilt and transfer to pen Pressure to get your desired results.  However as soon a you touch the pen to the tablet it looks like Wacom Tablet driver lock pen tilt  till you lift the pen,   The closest I can get to you bottom desire result is to set pen Pressure to both Shape Dynamics and Transfer.   And strokes look like Photoshop Brush strokes previews.  Shape Dynamics and Transfer controls can be quickly turned ON and OFF using the icons in the tool option bar.

You could also look at Lazi Nezumi.

http://lazynezumi.com/features

It's one of those things that having got used to it, you couldn't work without it.  It has a range of options including 'Pressure Speed Scalling'.  (I wonder if the gif will load here?)

Heck, I didn't realise it could do this:!

How cool is that?!