The lighting in my 3D plot is too small, how can I adjust its range?

hello,

i used isosurface and patch to create a 3D body (see screenshot) and now want to add some lighting for it to drop shadows and look more 3D-y. i played around with camlight, light, and lighting but all those options only illuminate a tiny area of my plot, which are the two conjoined bright red blobs in the screenshot, the rest (same hue of red) is quite dark. i tried moving the light source around manually (using the camera toolbar) and changing camera position, to no success. i also turned the plot around to check if the light's actually coming from behind, but that doesn't seem to be true either. so i'm a bit at a loss now and would be very grateful for suggestions on a fix.