My Canon 17-55mm f/2.8 IS is a serious piece of kit.  It is also my de facto “museum lens.”  The fast f/2.8 aperture combined with terrific image quality and image stabilization makes it the ideal tool for dealing with the muted lighting found in most museums.  To a camera museums are dark places; art galleries almost doubly so.  Too much light can damage certain artifacts and paintings, so the lights in these galleries are dimmed.  Flash is usually prohibited as well, as flash, too, can damage artifacts or artworks.   In order to shoot in such an environment you need a fast lens.  Otherwise your shutter speed will drop so low that you cannot create an image without it being ruined by camera shake.  Normally you would combat camera shake by using a tripod, but tripods are a no-no in museums.

If I’m going to a place where the available light is less than ideal, I grab my 17-55.  It is fast and has image stabilization, so camera shake is almost a non-issue (sloppy technique beats IS, however, so some care must be exercised).  However, ever since my wife gave me a 24-105mm f/4.0 L IS for Christmas I haven’t even touched my 17-55.  The 24-105 is also a serious piece of kit as well, but I was worried about losing the full stop of exposure.  Going from f/2.8 to f/4.0  would reduce my shutter speed by half, and since I was already shooting at unbelievably slow shutter speeds using my f/2.8 lens, I was concerned about how my f/4.0 would perform.

Turns out I needn’t have worried.  Taken in the National Gallery of Art:

0902_NGA_1151/8 second at f/4.0, ISO 400, focal length 24mm

The 24-105 is indeed a serious piece of kit.  1/8 second?  Crazy slow.  In a non-image stabilized world I would be shooting at 1/30 second minimum and to get that I would have to take my ISO to at least 1600. Image noise at ISO 1600 starts to become a problem and if faced with shooting at 1600 or not taking the shot I would probably opt for not taking the shot.  But the IS capabilities of this lens virtually negates the one stop loss versus the 17-55.  The extra stop of the 17-55 will come in handy in the darker galleries and in places like the catacombs under the National Cathedral, but for the time being my 24-105 f/4 is my new museum lens.