Can you purposefully reduce a spells range?
http://www.d20pfsrd.com/magic/all-spells/c/campfire-wall
A spell's range indicates how far from you it can reach, as defined in the range entry of the spell description. A spell's range is the maximum distance from you that the spell's effect can occur, as well as the maximum distance at which you can designate the spell's point of origin. If any portion of the spell's area would extend beyond this range, that area is wasted. Standard ranges include the following.
Are you asking if you could reduce the size of the spell's effect from the listed 20 ft radius? You can target a spell anywhere within it's range, but I'm not aware of any way to reduce its size.
^yes that is what I am looking for Ben. I am wanting to know if you can reduce the area of effect particularly the spell I listed but in general works as well.
(S) Shapeable: If an area or effect entry ends with “(S),” you can shape the spell. A shaped effect or area can have no dimension smaller than 10 feet. Many effects or areas are given as cubes to make it easy to model irregular shapes. Three-dimensional volumes are most often needed to define aerial or underwater effects and areas.
Only shapeable area spells can be reduced. Otherwise it emanates at whatever starting point you designate and spreads to the full cone, line, or radius.
There's also the metamagic Selective Spell, but that only works with spells with instantaneous duration, which Campfire Wall isn't.