Chances are, at some point you’ll be faced with the task of taking photos for an environment map. Doing it yourself means creating an EXR or HDR file, which has high dynamic range, and thus the lighting will accurately affect your scene.
Then you get lazy and just grab crappy .JPEG panoramas off the internet XD
In Cycles, you can fake such a photo into having more lighting information than it actually does by combining it with a Sky texture. Here’s the node setup. Sky textures assume a whole world’s lighting, so I use gamma to clamp out the higher levels, then make it a little more yellow with a mix node. On its own, the JPEG sky can’t go up or down in exposure like an HDR file; it’ll just blast it out with pixels or dull the lights. Lastly, the mapping node in the start lets you “spin” the world with the Z rotation.
The Og Bog Blog 