Spot light is not working in preview render Why is the Spot light no longer working? The problem occurs when I increased the scale of the model then applied the scale. I adjusting the lamp size to 2 meters then set the strength to 5000. On my second attempt I set the Lamp size to 50cm but it made no difference. The render remains dark. If I change the lamp type to Hemi or Sun then it works fine (figure 4).

Weird thing is if I disconnect the world output node as seen in figure 3. but with the use nodes still enabled then I get this result. There is still some light on the hair but the face is completely black.
If the sun is working (the hemi light isn't supported in Cycles – it basically just acts like a sun) the problem is most likely due to light falloff of your light sources. your scene is too large for the size and strength of your lamp.

You can confirm that by adding a light falloff node to the emission of your light as shown below.


quadradic is the default (and real world) falloff
linear is a linear falloff (double the distance, half the strength of the light)
constant is no falloff, this is i.e. used per default by the sun lamp




Adjust the falloff and strength to fit your needs.