was out this morning -30 windchill shooting from the car with my 7D and 500 f4
camera was in the car with me nice and warm and the lens was on a window mount sticking out in the cold I noticed that when i focused on something it would go in and out just a hair
just enough not to get a sharp focus is this because the camera in warm and the lens is in the could weather it is fine if i shoot outdoors and not in the car in the cold weather how you work around this ? not shoot in the car i suppose in cold weather
thanks for any help
You're probably getting a heat wave from somewhere, whether it's coming out of the window, exhaust blowing by the window, or the heat from the engine being blown that way.
You can turn the heat and car off while shooting, but you may still get a heat wave from the exhaust pipe or the engine.
The best way to beat it, is to get out of the car, and walk into the wind for 10 or 20 feet.