I was told... fact or fiction, that I should turn off the camera, change lenses indoors or at least out of the wind, put the new lens on the camera body first, camel hair brush the back of the lens that is coming off, and put the rear cap on.
So far, I have been very lucky with no dust specks showing up.

Anyone with better tips on procedure?.
Fred

This happens to be true among the pros.
They actually hang 2 or three cameras over the shoulder for quick access.
Good point!!

Next time I sell one of my oil wells, I'll remember that. :-))
Fred

I used to carry three, but it is TOO cumbersome.  Actually, carrying two isn't because of lens switching; it's about rapid access where a lens change would cause you to miss the shot.  The other reason is a strobe on the shorter lens (though the SB900 supposedly goes to 200mm range.)  Lenses are still changed outside and it is done rather quickly, usually without looking.  I change in the open, though in high wind/sand in Iraq I got in a vehicle to change.

What lenses are changed depends on the event/sport.  Usually one box carries a 70-200/2.8 or longer.  The other has 28-70/2.8 or 17-55/2.8; that is where the changes usually occur.

Yes, all manufacturers recommend turning off the camera.  They even recommended it in the film days.  Keeps a charge from being on the sensor.    Too much switching on and off--and forgetting.  Personally, I keep rear lens caps on the ones I take off the box.  Many people (not all) treat the employers' cameras worse than they would their own.  I buy mine.

Dust used to get in other places on the body.  These are mostly sealed now, even from moisture, by Nikon, Canon, etc.  Lens shades and UV filters save the front elements.

Bottom line, if you have time and want to save your lens mounts, turn it off and watch while you do it.  But, it's not as great a dust magnet as maufacturers make it out to be.

BTW--brushing the lens is NOT a good idea initially.  If you watch the Canon and Nikon repair folks clean cameras, usually you will see them blow the lens off before any brushing.  Then lens cleaner on the tissues.  

Done indoors.  Canned air.  BUT, must be used carefully.  The propellant can destroy the lens coating.  For cleaning sensors, the can is left on the table and the camera is moved around.

Non-spit technique in a pinch:  blow hard out of your mouth two long blows, then do one on the lens.  No spit.

The "fun" emergency lens cleaner (only do one lens a day!): A shot of whiskey then huff--not blow--on the lens.  Clean the condensation immediately.  Not a joke, it works.

An air blower is safer and more environmentally friendly than canned air - this sort of thing:

  http://www.bhphotovideo.com/c/product/541904-REG/Giottos_AA1903_Rocket_Air_Blower_.html

Canned air contains nasty chemicals as a propellent - see

http://en.wikipedia.org/wiki/Gas_duster

Brian

Just goes to prove how environmentally flawed Canon are 

Brian

Right.  I'm not advocating using canned air to blow on the sensor, but I do recommend it for blowing off the back of the lens or around the body/lens!  The little bulb blowers are not very useful at dislodging the more stubborn debris.  They're just not strong enough.  There are ways to safely use canned air to clean a sensor but much care and technique must be used: start the air before pointing it into the body, don't get close to the sensor, don't shut the air off while blowing into the body, etc.

Mike

Canned air around my camera and lenses makes me cringe.  On the outside of the body and lens if it is really dirty, ok, but never lens elements.  That’s where a Rocket Blower, soft camels hair brush and or a soft micro fiber cloth for stubborn areas come in handy.  The Rocket Blower works for sensor dust too.

If I do use canned air on a sensitive part, and I have done it, tho it makes me cringe, I place the can on a flat surface, and move the object I’m cleaning around.  That way, the chances of squirting some of the propellent in the can are greatly reduced.

My camera is always off when changing lenses.  I currently have 5 bodies, and using 3 at the same time at some events is the most efficient way to cover the event.