Sharp Is King

Strategies for waging the war between higher ISOs, sharpness and noise

Text And Photography By George D. Lepp And Kathryn Vincent Lepp

Labels: How-To, Camera Technique

This Article Features Photo Zoom

New digital cameras like the Canon EOS 5D Mark II (below, left) have remarkable ISO ranges, but with high sensitivity comes high noise. Noise ultimately will diminish the sharpness of a photograph. In this image, Lepp took advantage of a low ISO setting to keep the noise at bay and maximize the sharpness. The low ISO setting also insured deeper, more saturated colors, which in turn help the appearance of a sharp image.

In the quest for high-quality digital capture in the uncontrolled setting of the outdoors, we’re always seeking ways to overcome ambient conditions that pose obstacles to our photographic vision. Chief among these limitations is light—or, more precisely, its insufficiency or absence. Now one of our old allies in overcoming the challenge of low-light natural environments—increased ISO—is taking center stage with the introduction of new digital SLRs offering ISOs as high as 25,600! What do these advances really mean for outdoor and nature photographers working in the digital realm?

Why ISO Matters
ISO (International Standards Organization) ratings represent the sensitivity, and thus the speed, of photographic films. Higher ISO films are more sensitive to light and record an image faster than lower ISO films, but the quality of the image is compromised by the resulting increased grain, loss of sharpness and degradation of color. In digital capture, ISO equivalents represent the sensitivity and recording speed of the digital sensor. As larger sensors packed with more megapixels are coupled with faster and more efficient processors, digital cameras can achieve clean capture in extremely low-light conditions, realizing at high-ISO equivalents results that are impossible to duplicate with silver-based film. Our tests show there’s little image degradation at ISOs as high as 1600, and acceptable results can be obtained at even higher ISOs.

With film capture, changing ISOs meant changing a roll of film or, for some of us, carrying two cameras equipped with different films. But the twist of a dial or push of a button adjusts the ISO on digital cameras from frame to frame. Flexible ISO capability can resolve a number of photographic problems related to light, such as the need for a faster shutter speed to stop action, a smaller aperture to increase depth of field or even a slower shutter speed to suggest movement.

Gathering Light
To alleviate low-light conditions, we typically add electronic flash, or floods and reflectors in a studio. In outdoor/nature photography, projected flash and reflectors might work, but not at great distance.

To use one of our favorite, and most elusive, examples, consider the moose. Active and more easily found at dawn or in cool, overcast conditions, a moose doesn’t welcome a close approach, has a light-absorbing dark coat and is constantly moving as it feeds. What’s needed in this situation is a fast shutter speed to stop the animal’s movement and enough depth of field to sharply render the entire large body. Even with a fast telephoto lens, the optimum ISO of 100-200 won’t offer sufficient light-gathering capability to capture a usable image. Digital ISO to the rescue! By “dialing” up ISO 400, or even ISO 800, your D-SLR will allow you to choose the faster shutter speed and smaller aperture needed without a significant loss of quality.

Landscapes captured before sunrise and after sunset can yield a unique mood and unusual palette of colors that sometimes can be captured by a simple long exposure taken from a tripod. The problem can be the subtle movement of wind-stirred foliage or the clouds, moon or stars in the dark sky. If a sharp image is desired, the only solution to this problem is the increased ISO that will enable a shorter light-gathering exposure.

So why would you want to slow down the exposure time? Some cameras offer ISO settings as low as 50. This one- or two-stop desensitizing of the sensor, coupled with a polarizing filter, reduces light and lengthens the exposure to accomplish an effect, such as emphasizing the silky flow of water in a brightly lit stream or emphasizing the movement of a subject. Significantly longer exposure capabilities can be achieved with the lower ISO in combination with neutral-density filters.

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11 Comments

Keith Hutchings makes this comment

Friday, 19 December 2008

Great article!!! I love animal photography and pushing the ISO is sometimes a must to get the speed, especially in dim light. I'm thinking of getting a full sensor camera (new 5D Canon)but love the .6 cropping of the 50 for magnification. Always choices, keep up the great work and have a Merry Christmas and Happy New Year. Keith
Dave Bonney makes this comment

Wednesday, 24 December 2008

Thanks for sharing this information. Along those same lines, do you have a complete check list of how to obtain the best sharp image from anyone's camera? Other items like using mirror lock, shooting in RAW or sRAW, etc....
KristerP makes this comment

Friday, 02 January 2009

Thank you for this easy-to-follow article.
Bert Boyer makes this comment

Tuesday, 06 January 2009

Nice article. In ISO test #1 you state that "Some cameras have built-in noise-reduction software that can help, but it may render your image less sharp." I have a Nikon D90 and frequently shoot winter cross country ski races with a Nikkor 70-300 zoom. I am almost working in low light because the races are in Alaska in winter, so I push the ISO to 800 but have backed off from anything higher. I recently tried the built-in NR and things looked good to me. Do you feel I am probably reducing a significant amount of sharpness? Should I turn the NR off? I guess I should try both...but thought I'd ask. Thanks! Bert
Mike makes this comment

Sunday, 11 January 2009

Bert, I would use NR. I have a D200, which is definitely noisier than your D200, and I always use NR and leave it on "Normal." The reason for this is that you can always sharpen up an image using Photoshop or Capture NX (if you are shooting NEF, you can turn it on or off after the shot was taken because Capture NX preserves the in-camera settings and allows you to alter things afterward - Adobe Camera Raw makes considerably noisier Nikon images and the noise reduction it does offer...sucks, quite frankly). Alternatively, you can leave it off or on "Low" and a lot of noise that appears on the monitor is not visible in print. Images that were really noisier at 1600ISO with my D200 looked great as an 8X12 print. It just looked like slight film grain.
Bob Ross makes this comment

Tuesday, 10 February 2009

From ISO TEST: What's Your Threshold? Quote: #5." Set up your test with the intention of obtaining the best images possible. Use a tripod and a cable release, and select the optimum lens aperture (ƒ/8 to ƒ/11). Turn off autofocus, and if the lens has image stabilization, be sure the IS or VR function is turned off or your images will be consistently un-sharp. Work with manual exposure settings, basing the exposure on the exposure scale in or on the camera. " My comment/Question: I am new to the DSLR world and I was prepared to invest in a Nikon VR lens for my new D40. From what I had been reading I was starting to think that not buying VR lenses for all longer telephotos would be unthinkable, but if I am reading this correctly it sounds like the article is stating that a VR lens is a recipe for un-sharp photos????????
Gordon Ramsey makes this comment

Wednesday, 22 April 2009

Indeed. I like my photos like my knives: SHARP!
EricV makes this comment

Tuesday, 30 June 2009

HI, One question: If I want to take sharper image, should I shoot at very high ISO, thus got small aperture or Should I use regular ISO at large aperture? It so confused me since people told me that the smaller the aperture, the sharper the image and at the same time, the smaller the ISO, the sharper the image. Here are some pictures taken at very high ISO: 2500. http://omh1.com/phuchi/elcazador/pages/DSC_1327.htm thank you very much, EV
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Sharp Is King

Strategies for waging the war between higher ISOs, sharpness and noise

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