Hello again!
I tried to imitate fire light and made an orange spot light with high intensity and wide angle. It looked very nice in preview, but after rendering I saw ugly dark blots on my characters face.

In the image: for example, tip of the nose, upper lip, a spot under the lower lip, a beard-like shape (he doesn't have a beard actually!) and in some other places.

I understand that there's something I don't know about how to deal with light.  Can you push me in the correct direction because I am reading about various dark sports on renders but can't figure out which problem is mine? Mine is definitely about strong light and shadows, not about polygons and such.

Sorry, I forgot to specify that I use Poser 2014 with Firefly.

I have found a way to get it better, I don't know maybe there are other more subtle ways, please tell me if there are.

I changed the Shadow parameter of the light. It was 0,8 and I didn't want to change it because in Preview the color of the light was very beautiful. When I changed Shadow  parametre , light in Preview became lemon yellow, very ugly. ))

But it turned out that in the Render image the light was still warm orange with rich hues.
This is the result with 0,5 Shadow parametre for the orange light (render) (still some muddy water on the face):

And this is 0,1 Shadow parametre:

You should probably switch to Ray traced shadows. That looks like the kind of artifacts depth mapped shadows will produce.

Make sure to enable raytracing in the render settings and set bounces to at least 2.

You should probably switch to Ray traced shadows. That looks like the kind of artifacts depth mapped shadows will produce.

Make sure to enable raytracing in the render settings and set bounces to at least 2.