I do not change lenses around my dog (an Old English sheep dog) - I got a
hair on the sensor once ... very bad. I do not change lenses in verydusty environments if I can possible help it. I do check shots on my sensor often.
The absolute easiest way to keep the sensor clean is to never change lenses, and some photographers do that. They'll place a zoom lens on a camera body and never remove it. That will certainly work, but for the more serious shooter, it is quite impractical. The second easiest way is to hold the camera face down and change lenses quickly. Of course, that doesn't always work, but will certainly minimize specks on the sensor.
I always turn the camera off when changing lenses, and I turn the camera downward or straight out rather than face up to put the lens on. I blow out the chamber where the mirror and shutter are with a blower bulb, regularly.
I always point the camera downward when changing lenses, and I turn the camera off as well when I switch to a different lens.
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About Author / Instructor / Photographer, Kerry Drager
The content manager and course advisor for BetterPhoto.com, Kerry Drager is also the co-author (with Jim Miotke) of two books: The BetterPhoto Guide to Creative Digital Photography (2011) and The BetterPhoto Guide to Photographing Light (2012). In addition, he teaches this online photography course at BetterPhoto: Creative Light & Composition.
Be sure to check out Kerry's Pro BetterPholio website - www.kerrydrager.com - and his instructor bio page.
Also, he is the author of Scenic Photography 101, the photographer of the photo-essay books The Golden Dream: California from Gold Rush to Statehood and California Desert , a contributor to the books BetterPhoto Basics and Daybreak 2000, and a co-photographer of Portrait of California. In addition, Kerry was profiled in the April 1994 issue of Outdoor Photographer magazine and in Vik Orenstein's 2010 book The Photographer's Market Guide to Building Your Photography Business, and his website was showcased in the January 2003 issue of Shutterbug magazine. Plus, his work has appeared in magazines, Hallmark cards and Sierra Club calendars, and in advertising campaigns for American Express and Sinar Bron Imaging.
Also see his Visual Creativity photography blog, and follow Kerry on Facebook.
Kerry lives with his wife, Mary, in the country near Sacramento, California, with their six Newfoundland dogs, four cats, two horses, and a mixed terrier.