Rangefinder Magazine
May 2006

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The Truth & Consequences of Digital Photography by PETER KOTSINADELIS
 

Even with what seems a perfect exposure, the whites in the image may be outside the latitude of what a digital image sensor can handle. Fujifilm Finepix S2 Pro, 24mm lens. Image by Jerry Costanzo

With all the advances in digital photography, one would think it is the solution for every problem a photographer may encounter. But as with any new technology, there are both advantages and consequences. While many of these consequences, or drawbacks, vanished over the last few years, there are others that still remain.

Yes, digital photography is certainly the fastest growing market segment in the photographic industry and, like a fine wine, it will only improve with time. But like any technology, it is not perfect. And the real question is, “Will the consequences of digital imaging really impact my photography?”

Digital and Film

Photographers using digital or conventional imaging are quick to point out the benefits and at the same time the drawbacks. If there were such a thing as a perfect medium for photography, everybody would be using it, and photography as we know it would not really exist. Many have called the digital camera the Polaroid of the new century, but this nickname understates digital photography’s advantages. While digital cameras do provide an instant image for review, there is a great deal more to digital than just that.

One of the earliest draws to digital imaging was the potential cost savings realized by eliminating the need for consumables like film and chemical processing. But the consequence was the need for a faster computer with greater disk storage for digital images, memory cards, and additional time the photographer would have to spend in front of the computer screen to create the finished images. More time in front of the screen meant less time for income-generating work with clients. And again as digital technology advanced, cost savings were tempered with the need for newer digital cameras, larger memory cards, an upgraded computer system, photo-quality printers, etc.

While much of this has been covered before, the facts regarding the consequences of using a digital camera itself have rarely been discussed. One of the most often overlooked consequences is limited exposure latitude, or what is commonly referred to in digital parlance as dynamic range. While the exposure latitude of modern negative film is so good it often negates the need for precise exposure, digital cameras are quite the opposite, with very limited exposure latitude. This is especially true when photographing a subject where white is the dominant color. Even though the rest of the image may be properly exposed, the whites may lose detail if outside the dynamic range of the digital camera and image processor (see image No. 1).

So far the only vendor to address this limitation is Fujifilm with the new Super CCD SR sensor technology in the S20 and S3 (see “Here Come the ZLRs” in the October 2004 issue of Rangefinder).

Large group shots require enough pixels to cover a face so that it shows detail when enlarged. Here the Kodak DCS Pro SLR/n does the job. Lens: Nikkor 14mm. Image “Face in the Crowd” by Greg Sargent Photography of San Jose, CA.

File Types

One of the more interesting consequences is file type. You can set your camera to record images and store them in RAW format (typically proprietary to the camera manufacturer), TIFF, JPEG or JPEG 2000. Some newer cameras offer the option of recording two file types at once (RAW and JPEG), but it often requires proprietary software to access both formats from the recorded image.

If you elect to use RAW format, you generally have access to a greater dynamic range. However, RAW files are larger in size and have the disadvantage of taking more time and space when saving to the camera’s storage media. If you opt for the JPEG format, you have less dynamic range than with RAW format; however, JPEG files are substantially smaller and can be saved to memory more quickly, thus freeing up the camera for the next shot. There is also the option of setting a lower resolution JPEG, but medium or small JPEG files are smaller because they record the image at a lower resolution. The compression can really detract from the image when enlarged.

JPEG 2000 is a relatively new compression method that was designed to eventually succeed the aging JPEG standard. It offers compression ratios that do not generate artifacts such as the jagged lines or blocky edges sometimes found in JPEGs. Although this format is supported in newer versions of Photoshop, it is not yet widely acccepted and to date has not been used in digital cameras.

TIFF files are an industry standard but, like the RAW format, produce a large file size. There is little advantage in using TIFF over RAW format, and as a result few camera manufacturers continue to offer the TIFF format as an option.

Digital images can be manipulated quickly and easily, as in this beautiful collage (a page from a wedding album). Image copyright © Kamran Zohoori, Picture2000.com

Pixels

Another consequence of digital imaging is the limited number of pixels. You’re probably reading this saying, “Hey, what limited number? I have millions of pixels!” While manufacturers continue to pack more pixels into image sensors, the physical size of the image sensor often increases as well, so there is not necessarily a greater number of pixels in the same area. If more pixels are packed into the same size image sensor, these smaller pixels will typically generate more noise, so manufacturers may adjust the size of the sensor and the number of pixels to achieve a good balance of resolution and noise. For example, if you compare the EOS 20D to the EOS 1D Mark II-N, both have essentially the same number of pixels—but the image sensor on the 1D Mark II-N is physically larger, and so is the actual size of each pixel, to compensate for possible noise.

There is also a difference between the actual number of pixels in an image sensor and the “effective” number of pixels, with the effective number being the number of pixels actually used in the creating the image. For example, Canon’s EOS 20D has a sensor that is 22.5x15mm, with 3600 pixels horizontally and 2360 vertically, totaling 8.4 million pixels. However, the effective number of pixels is really 3520x2344, or 8.2 million, about two percent less.

Obviously, the real key to having greater digital resolution is to gain more pixels in the same area with reduced noise (see table 1, page 100). One example is Canon’s EOS 1D Mark II-N, with 8.2 effective megapixels, compared to the original EOS 1D, with 4.2 effective megapixels. Both have a sensor with the same physical measurements of 28.7x19.1mm, but the new Mark II-N has almost twice the number of pixels. For those more familiar with film, this is comparable to using a much finer grain film (the EOS 1D Mark II-N) capable of producing an image that is the equal of the earlier emulsion (the original EOS 1D) at twice the size, say 16x20 versus 8x10.

Another example is found comparing Fujifilm’s Finepix S2 digital SLR to their new Finepix S3 digital SLR. Both have sensors that are same physical size, but the S3 claims 12.3 million pixels. Are the pixels smaller? Well, yes and no. On the CCD in the Finepix S3, there are two pixels in a space previously occupied by only one pixel on CCD of the Finepix S2. These pixels are smaller and are used to record the same area of a subject at different sensitivities to increase the dynamic range—but the design really does not change the effective number of pixels, which technically remains at 6.1 million.

One of the more difficult images for digital cameras is the large group shot. The consequence of using digital for these shots is that if there are not enough pixels over that small face in the crowd, the image will lack detail. This is where cameras with more pixels in the image sensor have the advantage. For example, the new EOS 1D Mark II and the EOS 1D have the same sensor size, but the newer Mark II has nearly twice the number of pixels in the same area (see image No. 2).

Moiré

Moiré (pronounced mwa-ray, but more often pronounced more-a), as it pertains to digital cameras, is basically when two patterns overlap and cause interference to the image sensor attempting to correctly render the image. Well known in the television industry for years, you can occasionally see this as a rainbow-like pattern that appears when people wear garments that interfere with or confuse the TV camera’s image sensor. It’s the same idea in digital photography, but will vary between cameras. Those with larger pixels typically have more trouble with moiré than those with smaller pixels (the opposite of noise generation). To compensate, camera manufacturers use moiré or anti-aliasing (also called low-pass) filters that reduce this unwanted effect, but often these filters will also soften the image.

So What’s Best?

Digital photography offers many advantages over conventional photography, and is especially attractive because of potential savings gained by eliminating film and processing costs, having instant image review, and immediate image manipulation without need for scanning. However, digital imaging may involve a large initial investment and a considerable learning curve. As with any new technology, there are consequences to be considered, but many photographers have already found that adapting this technology to their business provides significant benefits that quickly eclipse the drawbacks.