Originally posted by bdavis The only surefire way I know of to prevent fogging of glass is to avoid rapid shifts in temperature. Easier said than done; I've made genius moves like waltzing into a greenhouse only to have to sit and wait out the fogging. Bring along a microfiber lens cloth.
Agree with Beth here. Nikon makes a specially coated "fog" microfiber cloth that is
slightly better than the plain old vanilla kind. I've tried every which way I know of to prevent condensation, but nothing seems to work particularily well except for good old "sit down and wait". The "fog" micro fiber cloth will let you get a shot off or maybe 2-3 but it will still fog back up until your equipment has acclimated itself to the new environment. One thing I've found helps in winter where a relatively short walk (15 minutes or under) outside is necessary and that's to wrap camera and lenses in some sort of "jacket". I have a tight fitting neoprene(sp?) camera case and the "slingshot" lens cases that work pretty well if I going from warm to cold to warm again in the winter, as long as I'm not spending a long time out in the cold. I've walked into a "tropical" set greenhouse after 15 minutes in sub freezing temps with no problem as long as camera and lenses are bundled up and cozy.
NaCl(give time, time is the only sure cure)H2O