One more reason to not use a lens hood.

[WhoIsSerafin]

[Rob Trek]

Interesting. Might have to test this myself.

[DeMorcan]

I see Pros use lens hoods in the artic when shooting Polar Bears. He is right if you take a warm camera and hood out in cold weather, there will be air currents in the lens hood just like in a telescope. You do need to let the gear cool down and then put in the warm battery when you are ready to shoot. A warm hood and camera will have some issues if you just walk outside and take a test photo. If you actually use the gear outside there is no issue. That is also why I have custom made tubes for my telescopes that were made a few inches larger than the mirror. The air would fall or rise out faster. The air has no way of moving in the lens hood normally. After the camera and lens are nearer air temp, No problem. If you do have warm air in the hood and it is soft, you can blow in the lens (with the cap on or use an air lens cleaner to move the air out. This speeds things up somewhat.