Sorry if my first comment seemed somewhat mean.
Now, for calclight stuff.
Light precision should be left at default, if you wish to increase the sharpness of the shadows there are two ways:
1: Make more subdivisions on large surfaces- If you make a cube above a large surface and calclight you may find that the shadow isn't terribly sharp, but over a smaller cube it may be much sharper. This is due to individual light maps being made for each surface. The light precision setting limits how big each light map can be per cube. If you have a large surface then it would require more area for the light map than is allowed for a single face. If you subdivide it then there are more surfaces which can be lit individually to achieve the combined effect
2: As you probably guessed from 1, change the light precision. The problem with this though is what you may have noticed with my other comment. FPS drop. If you must change precision, lower it incrementally until you get the desired effect, DO NOT just set it to 1.
There are commands to set light precision and light error, but you'd be best off using the gui. When in game hit ESC to bring up the menu, click "Editing" then find the "Lighting" tab.
As for your /calclight 1 that you used, you simply use /calclight, or /calclight -1.
Calclight will use the current settings seen in the GUI, calclight -1 will do so but without model shadows or light map anti aliasing. I've not used calclight 1 since the last release, but I'm guessing it changes precision when you use it.
For light error, simply put... Don't touch it.
Light error is used to fix visible polygon boundaries visible after a calclight. Only use this value if you have good reason.
