So I wanted to share this because I am so impressed with the results. I was looking around the Internet because I wanted some Photoshop brushes that looked like night lights being cast onto buildings. I found this "IES Creator". It looks like it is used by lighting designers to see the pattern of different lights when cast on a wall. But it just so happens that if makes fantastic Photoshop brushes. You can download different .ies files in a bunch of places that emulate specific lights which is pretty cool.[/dropcap]
After fiddling with the settings I was able to come up with these brushes that look pretty nice. All you need to do is get a screen grab (no way to export an image) and bring it into Photoshop, invert the image and make a brush (Edit > Define Brush Preset). I would imagine that bringing these in as masks into Nuke would be equally as nice to do some comp lighting tricks. It has been nice painting with these as they add a lot of complexity pretty fast.
Here is a screen grab of the interface of the "IES Creator". Move around that red line and it changes the profile of the light.
If you know of a diffrent ies creater program I would be interesting in checking it out--please post.
Download IES Creator Here