I feel like this is something I should know...but I don't. Is it hard on the glass to shoot outdoors in a really cold (chicago in winter) or really hot (like at the equator in summer i guess?) environment for an extended period of time. do lenses contract or expand or anything? I'm not planning on shooting in antarctica or anything, but just want to keep my one lens in good shape.

anyone know anything about this? is it even something to be concerned about? or am i complete dork for asking?

The most important thing to remember is to let your gear cool off or warm up slowly, so when you go somewhere really cold, leave the camera and lenses in the bag to cool down slowly, same with bringing it back inside, in the bag till it acclimates. The other thing to remember is that batteries (cameras and flash) don't work as long when they're really cold.

Limiting exposure to extremes is a good thing, don't leave your gear outside all night to freeze solid (seems obvious but ya never know...) ;-)

~Bill

any bad weather, whether hot or cold or sandy or foggy can and is bad for camera gear, but it takes quite a bit before you'll ever notice anything, any routinely cleaning and having them serviced wouldn't be a bad idea.

Moisture can lead to fungus on the glass. High heat can create imperfections in the glass or move the elements (Flourite elements especially, which is why many long lenses are white to reduce heat internally)

Ya, moisture can be a big deal... I had a camcorder in central america for a couple weeks that would just say 'moisture detected' on the screen when I turned it on and not function at all... worked fine when I got home.

And interior condensation is the big reason for letting things warm up slowly...

White Lenses = Canon wanting to visually stand out..... (IMNSHO) ;-) (easily my least favorite part of my new 70-200mm IS lens is the color... I like to be a bit sneaky and that lens grabs everyones attention)

they definetly use it as a marketing tool, but then again Sony, Minolta, and Olympus have had white teles for a while, and some Nikkor glass was available in it as well.

definetly let things slowly come to the right temp. Just walking around the zoo and going in between the outside and a rainforest exhibit fogs my whole weather sealed setup.

But I also take my gear to the Dominican Republic every summer in July, talk about moisture in the air, and never had a problem.