i need to get sharp shadows with blender cycles render. i placed plane as light emitter. i can’t able to control the shadows. I need the shadow to be very sharp…
An emitter plane is the same thing as a area light. It’ll never ever cast a sharp shadow for what it is.
An area light.
Either scale it down until it’s almost a pointlight (dont forget to apply the scale) or the best chance is to use a sunlight and in the light settings set the size from 1.0 to .001 or whatever matches your scene.
This way you get sharp shadows.
hey buddy… thanx a lot… will try it and update u… :o 
I’d really like to know how to get sharp high contrast shadows with sun lamp. I set sun size to .001 and I still don’t get the results I need.
Since light in cycles behaves according to physical laws, you need to model your lighting that way. A shadow becomes sharper the smaller it appears from the surface point you are observing. A small patch of light is more likely to be obstructed 100% or 0% and therefore the shadowing will be either 100% or 0% most of the time. Conversely, a large patch of light is likely to be obstructed only partially for a given point, this results in a soft shadow falloff.
A point light, being infinitely small, will always give a perfectly sharp shadow, because it is always completely visible or obstructed.
Unlike in blender internal, there is no way to have shadows projected through spot lights - shadows in cycles occur naturally through the obstruction of light source.
I’d really like to know how to get sharp high contrast shadows with sun lamp. I set sun size to .001 and I still don’t get the results I need.
Did you set the scale in the light settings? Scaling the light object will not affect the shadow.
Emitter needs to be small and at some distance for the shadow to sharpen.
Cut down on the bounced lighting that may “fill” the shadows.
Try to keep emitter location perpendicular to the area where shadow falls. If the shadow falls on slope, shadow edge area can spread out over wider area making it look fuzzy. Locate object right up next to the area where shadow falls as well, to minimize shadow spread.
I’ve set scale in lamp settings, not scaled actual sun.
I’m new to Blender, but I had the same problem and did find luck by turning the world lighting to black and then following the steps above; making the emitter plane very small, very strong, and very far away. Good luck.
But why limit to 0.001? use zero size, in point and sun light, they will produce ideal sharp shadows.