Pixiq

When you shoot subjects that are white or that have white areas in them, you have to be especially critical in the exposure.  The last thing you want is to blow the highlights such that there is a loss of texture and detail. If that happens, the picture usually can't be repaired in Photoshop and it ends up in the trash.

The photo of the black-browed albatross I photographed in the Falkland Islands is a good example. The subtle texture in the white feathers had to be retained, and even though the lighting was soft and diffused from an overcast sky, it would be very easy to overexpose the feathers. 

I use two techniques to prevent overexposure in the highlights.  First, I always shoot in RAW mode.  This is the first line of defense in protecting the vulnerable highlights.  Had this picture been taken in JPEG mode, I'm sure the brightest areas of the feathers would have become solid white.

Second -- and I know many of my professional photographer friends disagree with me on this -- I underexpose my images by 1/3 or 2/3 f/stops.  This further protects the highlights, and if the pictures turn out to be slightly dark, I simply lighten them in Adobe Camera Raw (or Lightroom) until the exposure is perfect.  This slight amount of underexposure does not introduce additional noise, and it gives me complete control over the digital image. In this way, I never take pictures that have blown highlights.

This image is uncropped.  I used a 500mm f/4 IS telephoto to fill the frame with the birds.  My ISO was 400, the shutter speed was 1/1250, and the lens aperture was f/8. I turned the IS feature off because with most lenses your pictures will not be sharp if you use the image stabilization feature with a tripod.  I used a Wimberly head on the tripod to manage the large lens with ease.