Choosing a Digital Camera

If you don't have a digital camera and are trying to decide whether to buy one, you've got some thinking to do. The question "Which is better, film cameras or digital cameras" is a complicated and multi-faceted topic. The short answer is "it depends". 

For most point and shoot picture takers it does not make too much difference. It depends on what you want to do with the photos. For example, if you want immediate availability of your shots to send to friends across country, digital makes more sense because you can download and email your photos as fast as you can get to your computer. Also, editing of your shots is possible with digital, although you could scan a film photo and then edit it. Digital photography is still not as good in some ways as traditional film photography. However, it's only when very large prints are important that affordable digital cameras suffer by comparison. 

Most people do not take professional photographs like this and can use digital cameras for most, if not all, of their photos. A two or three megapixel brand name camera should give you beautiful 4X6 or 5X7 inch color prints. See digital cameras for under $200. 

Over the history of photography, photographers have shown a willingness to forgo some quality for cheaper, easier processes. However, in the digital arena, what often appears to be inferior is really just different. Improvements in the digital camera arena are being made all the time. Last years models are quickly replaced with new and improved models. In the coming years digital has greater potential than film.

 Moore's Law

Anyone who has bought a computer knows the perennial questions, "Is now the time to buy, or would it be better to wait?" As the ability to put more and more transistors on a chip increases, the cost per unit of computing power falls. In 1965 Gordon Moore, one of the founders of Intel Corporation, predicted that the density of transistors on a chip would double every year and a half. His prediction, known as Moore's Law, has turned out to be very accurate. In 25 years, the number of transistors on a chip has increased from 2,300 on the 4004 in 1971 to 28 million on the Pentium III Xeon processor in 1999.

Moore's Law drives innovation forward at a disturbing rate. In this environment it's only natural to think you should wait to buy a digital device because in six months you'll get much more for your money-and you're right! The problem is that you can use this rationale to delay a purchase for years, and even decades. New and improved models will always be six months away. In the computer world, power users buy their computers when they need them, knowing full-well that they'll pass them on in a few years and replace them with newer models. If you're really serious about photography, you may have to shed your old willingness to invest in a new camera system every decade or two and replace it with a 2-3 year time frame.

  The pros and cons of digital photography

Probably the biggest question of all is whether you want to buy a digital camera at all. There are pros and cons to the decision and you don't need a digital camera for digital imaging. You can always use a standard film camera and have selected slides or negatives scanned at your local photofinisher. Here's a table that weighs the pros and cons of each approach.

Photography: Beyond the amateur
Arguments for traditional film cameras.

Traditional 35mm Film SLRs

The 35mm single lens reflex (SLR) is most folks' idea of a serious camera. SLR means that the same lens is used for viewing and taking pictures. A mirror in the body directs the light from the lens up into a prism for viewing, then flips up out of the way just before an exposure is made. These are extremely versatile instruments in the right hands and can take beautiful pictures if used with care.

If you are serious about photographing people, animals, or travel, then an investment in an SLR may be wise. A good budget system would include a cheap body, a 50/1.8 lens, and a tripod. Add a portrait lens, a big telephoto, or a wide angle depending upon your needs. If you have relatively big bucks, consider really wide angle lenses (20mm or wider), high quality telephotos (300/4, around $1000), or professional zooms ($1000 and up). If you are tempted by the consumer zooms (apertures of f/4 or f/5.6 and prices of $300 or less), then you should ask yourself whether a point and shoot wouldn't be better.

Canon and Nikon enjoy an overwhelming dominance of the professional 35mm SLR market. There are good reasons for this and the dominance tends to be self-perpetuating because off-brand manufacturers don't have much incentive to invest in R&D. 

One can rent exotic Canon and Nikon lenses (e.g., a $4000 300mm f/2.8 telephoto) in most major cities but rentals for other brands are virtually non-existent. Finally, Nikon and Canon are probably the lowest cost systems for serious photographers because they have high resale value and economies of scale on the big lenses (e.g., a Nikon 80-200/2.8 costs less than a Pentax 80-200/2.8 because the Nikon is mass-produced for photojournalists whereas only a handful of Pentax's customers are in the market for lenses that cost over $1000).

Leica makes some fairly nice, very expensive lenses. These handily outperform the low quality, cheap lenses that Canon and Nikon were forced to make to compete with Sigma, Tamron, and Tokina. The $3150 Leica 180/2.8 does indeed outperform a $120 Nikon 70-210 zoom set to 180. That doesn't mean it outperforms the $700 Nikon 180/2.8, which is what a professional Nikon photographer would be using.

Whatever you do, don't spend too much on the camera body. It is much better to have a good lens on a cheap body than vice versa. The body is ultimately just a light-tight box; the lens forms the image. Also, remember that if you get more serious, you'll almost surely want a second body.

The 35mm SLR is a 50-year-old technology, the market is quite competitive, and the systems have become rather similar.  Thus if your budget is limited to under $400 what you want is a Nikon N65 + 50/1.8. 

Amateur Photographer, an English magazine, tested every 50mm lens on the market in May 1991. All performed very well, since the 50 is the easiest lens to make, but their expert rated the Nikon 50/1.8 AF lens as the best out of the 25 lenses tested, including brands such as Zeiss and Leitz and more expensive faster lenses such as the Nikon 50/1.4. The Nikon 50/1.8 costs around $90 and has a reasonably nice manual focus ring, unlike its Canon counterpart. Finally, you'll want to budget enough for a tripod.


Medium Format Cameras
Medium format cameras use 120 and 220 film ("rollfilm") and produce a negative approximately four times the size of a 35mm negative. Unfortunately, this makes them four times the size and 4-16 times the price of 35mm equipment. A Hasselblad or Rollei won't fundamentally do anything that a Nikon can't.


Point & Shoot
If you are serious about photography, you should have a camera with you at all times. No matter what else you buy, then, you'll probably also want a point and shoot camera, the smaller the better. Most of the knowledge that one uses to make images with a real camera can be applied to point and shoot photography. Most people don't realize that their P&S cameras have exposure and focus lock (press halfway down), the same reliable flash exposure control system as a new Nikon and can give great results on a tripod.

You can't get really extreme perspectives with a P&S, i.e., none come with 20mm or 200mm lenses.

Digital Cameras
Today, does it really make sense to buy a 35mm film camera? The best digital cameras offer comparable image quality, instant previewing, and near-instant sharing via the Internet. 

There are however some issues with digital cameras. Those under $1000 are aimed at point-and-shooters and people accustomed to SLRs will be disappointed in the lack the creative freedom and tiny viewfinders. The $2500-4000 single-lens reflex digital cameras, e.g., Canon D30, Nikon D1, Fuji S1, are built to accomodate legacy interchangeable lenses from 35mm systems. It is nice to be able to use your old Canon EOS or Nikon F lenses, but the small image sensor inside the digital SLR changes the effective focal length. A 50mm normal lens becomes an 80mm portrait lens. A 20mm extreme wide angle lens becomes a 32mm slightly wide angle lens. What's worse is the knowledge that you're lugging around lenses that are twice as large and heavy as they need to be. A lens for a Canon EOS film camera must project a large enough image to cover the 24mmx36mm frame of 35mm film. But the sensor on a D30 is only 15mmx23mm in size. Attaching a 35mm film camera lens to the D30 is sort of like using a medium format Hasselblad lens on a Nikon. It will work, but why would you want to pay extra money, carry extra weight, and use a camera bag that is twice as large? 

The less obvious problem with digital cameras is that they force the photographer into the world of the computer. With film, you only have to learn how to work your camera, remove the film and take it to a lab. For long-term archival storage, a metal file cabinet serves nicely. After you've filled up the flash card on your digital camera, you need to make sure that you've got a working computer nearby with appropriate hardware to effect a transfer. To produce a physical image you could buy and learn how to use a high-quality ink-jet or Fujix printer. Alternatively, you could figure out how to hook your computer to the Internet, upload the image to a lab, and get a finished print in the mail. 

For long-term storage and retrieval you could rely on an Internet photo storage service. But with dotcoms going belly-up every month, do you really believe that any of these services will be around for your great-grandchildren? If not, you'll need to come up with a strategy for organizing your images on your own hard disk. You'll have to purchase a tape drive or some other backup device and learn how to use software to ensure that your data are properly backed up. You'll have to discipline yourself to actually perform the backups and change the tapes periodically. You'll have to discipline yourself to verify the tapes occasionally.

Film vs. Digital: Quality Basis

Which is better, film or digital? What megapixel resolution does digital need to achieve to equal film image quality?

ANSWER: That depends.

There are many factors that affect the objective and subjective measures and assessments of image quality. For this discussion, we will only be concerned about those that are specific to the capture medium. With film images, the film ISO speed, type and brand, and film format (size) are of primary influence as they determine the size, density, structure and photosensitivity of the silver halide particles. These characteristic properties of a given film determine its general resolution capabilities, dynamic range, and perceived graininess. With digital images, the size, spacing and specific design and performance characteristics of the photosites (pixels on the CCD or CMOS sensor array) on the capture device sensor array determine important image characteristics such as resolution and noise. Further components such as the ADC and color reconstruction algorithms combine with the specifics of the capture sensor array to determine dynamic range, tonal and color resolution, and susceptibility to aliasing.

The biggest obstacle in comparing film images to digital images is the appearance of grain in film enlargements. Some feel a certain degree of resolved grain in an image adds to the overall aesthetic appeal, however all agree that at some point resolved grain structure in an image becomes objectionable. From a more objective point of view, grain structure resolution interferes with fine detail, increasingly so as the grain structure size increases in relation to the size of the detail. While digital images can suffer from a similar factor in the form of noise (caused by a number of things including optical & electrical crosstalk, dark signal non uniformity and photosensitivity non uniformity), most high quality digital capture is now virtually noise free, creating a point of comparative characteristic dissimilarity between film enlargements and their digital counterparts.

FILM:

Visible grain structure in an image results in an inconsistent, "grainy" appearance in areas that should be smooth or even in appearance, and can interfere with fine detail.

Kodak defines "Graininess" as: "The subjective perception of a mottled random pattern apparent to a viewer who sees small local-density variations in an area of overall uniform density." Grain resolution in images can range from barely noticeable to that which essentially ruins the image. The larger the grain structure, the more objectionable the affect. The two main factors that determine the resultant grain size in the final print are: 1) the grain size in the film (faster films have larger grain structure and print film often has larger grain than slide film of the same speed), and 2) the amount or degree of enlargement. Slower films have smaller grain structures and therefore allow for larger prints. Larger film formats require less enlargement and therefore allow for larger prints. The degree of enlargement of any given film image at which grain becomes objectionable is completely subjective.

Kodak has attempted to make the relative amount of visible grain in prints of various sizes from Kodak print films predictable through the Kodak Print Grain Index system.

DIGITAL CAMERAS:
Digital cameras can suffer from noise, lower color resolution (this can actually result in more contrast - more perceived image sharpness), and lower dynamic range. Digital cameras have to capture images very quickly, at common and traditional "shutter speeds." The speed with which a digital camera system must work eliminates digital capture methods used in film scanners and some high end digital camera backs (used by pros for still studio photography) to produce high spatial and tonal resolutions. This need for speed in capture results in an inherent trade off or balancing act in digital camera design. For this reason, as compared to film scanner digital capture, digital cameras have less sensor spatial resolution, less color resolution, and less dynamic range.

Noise is becoming less of an issue. Today's high quality sensors (of the right size and spacing) can produce virtually noise-free digital images. These types of sensors are found in current generation pro-quality digital SLRs.

All digital cameras, with the exception of those using the new Foveon X3 sensor arrays, use a staggered color filter array. This means that each pixel (individual CCD or CMOS sensor) in the sensor array is dedicated to recording only one of the three primary colors (red, green, or blue). Thus, spatially, the color resolution is disproportionate (lower) to the intensity resolution. Digital cameras use algorithms to "reconstruct" the color information. The mathematical reconstruction of the color information is not perfect and digital images produced this way suffer from reduced color resolution in comparison to film images. 

This "reconstruction" (it's really more of a mathematical guess based probability) can also fail and result in color fringing, moire patterns, or false or missing detail when pattern frequencies in the scene are of a certain relationship to the sensor array's nyquist frequency. Foveon's X3 technology makes it possible to make each sensor capable of and responsible for sensing all three primaries, thus essentially resolving the color resolution issue. Fuji's innovative, honeycomb-like Super CCD array (like in the Fuji S2) also serves to partially address this issue (though not nearly as deftly as the Foveon technology) by simply increasing overall effective spatial resolution.

Digital cameras do not have the dynamic range capabilities of film, and dynamic range can vary greatly among different digital cameras. When dynamic range specifications can be found for given cameras, they are most often useless for comparison purposes because different criteria and measurement methods were used. Low dynamic range results in a higher contrast image with less subtle tonal detail. Digital has the inherent potential to outperform film in this category. New technologies promise to solve this point of disparity between film and digital cameras.

THE BOTTOM LINE:
To really answer the questions posed at the top of this page, one must understand the many component concepts involved in imaging that affect objective and subjective image quality and specifically resolution and sharpness. 

Both objective and subjective assessment measures are called for. There is also the complicating issue of grain. Film images can suffer from grain structure resolution (visible film grain in the image), while a good (noise free) digital image is comparatively grain free. Therefore a film image with high detail resolution can appear inferior to a good (low noise) digital image with lesser actual detail resolution; an image that is objectively superior in that it has has greater detail can look inferior in an overall subjective analysis. The necessary combination of objective measures like MTF frequency resolution and subjective overall image appearance assessments make this a difficult subject. Luckily, interested and knowledgeable persons have engaged in testing designed to answer the question; how much digital resolution does it take to equal the image quality of film?

Unbiased testing so far has indicated that the 6MP SLRs (Canon EOS-D60, Fuji S2, Nikon D100) produce subjective image quality very close to that of fine-grained 35mm film (Fuji Velvia, Provia 100), having less detail resolution but less noise (grain resolution) than film. 

The sensor arrays in these cameras use different individual pixel (sensor) size and spacing than found in digital point & shoot cameras. This gives them sensitivity, dynamic range and lower noise benefits in addition to their greater resolution in comparison to digital point and shoot cameras. Objectively, images from these digital cameras are inferior in both detail, color and tonal resolution to the 35mm comparisons, but the grain factor in the film images influences overall subjective analysis and many feel the digital images are very close and even equal in overall image quality to the 35mm film image comparisons.

The 11 MegaPixel and higher SLRs (Kodak DCS 14n, Canon EOS-1Ds) should produce overall subjective image quality equal to or above fine-grained 35mm film. Again, the grain factor comes into play here with enlargement, but analysis tends to indicate that this level of digital camera has caught up with 35mm film.

Film vs. Digital: Cost Basis

Assumptions: to compare apples to apples, we assume 27 pictures are taken each month per camera.

The chart below compares a throwaway 35mm camera (the least expensive option for pictures) to a middle of the road consumer digital camera.

 

camera	month	cost of camera	developing costs	print cost	total
35mm disposable	1	$6.00	$3.00	$3.00	$12.00
digital	1	$400.00	$0.00	$8.00	$408.00
35mm disposable	2	$6.00	$3.00	$3.00	$24.00
digital	2	$0.00	$0.00	$8.00	$416.00

35mm disposable	3	$6.00	$3.00	$3.00	$36.00
digital	3	$0.00	$0.00	$8.00	$424.00
35mm disposable	4	$6.00	$3.00	$3.00	$48.00
digital	4	$0.00	$0.00	$8.00	$432.00

Summary: the digital costs escalate $8.00 per month (basically printing costs) while the non-digital costs escalate $12.00 per month (camera plus print costs). That is a difference of $4.00 per month more for the 35mm. 

To offset the initial cost of the digital camera, it would take 100 months ($400/$4) or eight years of picture taking to even the costs. Technology advances most likely over the course of eight years could obsolete today's digital cameras. 

Therefore, in conclusion, the decision to go digital or not really comes down to a choice of what you want to get out of your picture taking experience. On a pure cost basis, not considering anything else, you would not go digital. If you just want to point and shoot and get a picture, you would not go digital. Even with film, you can get picture CD's from your photo finisher so you can share images on the internet or you could use a scanner to digitize your images, assuming you buy a computer and know how to use it or go to a retail shop which has a working photo scanner (costs can be high).

One of the biggest drawbacks to film cameras however, is the inability to instantly see the results of the picture you just took. Another of course is the limited number of pictures you can take before the need arises to load in fresh film. 

Options such as image editing and computer document composition are some of the features digital photography provide. 

Film vs. Digital

The number of U.S. households owning a digital camera doubled from 4.4 percent in 1999 to 9.3 percent in 2000. Digital cameras are far from reaching their saturation point and will likely experience strong growth for years to come. Some people even say digital will replace film.

There are many arguments for either side of the digital or film debate, but in the end film is likely here to stay for quite some time. Consumers have always known film. They know how it works, how to turn the film into pictures, where to go to pick up the pictures and how much it will cost. They are familiar with the quality of the pictures.

Digital does have the advantage in that endless numbers of pictures can be shared with anyone without costing a cent.

When a customer drops off a roll of 35mm film, they know the cost will be $6.99 for a roll of 24 exposures, it will be ready in an hour, the quality is guaranteed, and most important of it all — it's so easy.

Compared to the average price of a traditional 4x6-inch print, which is around 25 cents to 28 cents, digital is now very competitive. Wal-Mart has self-service machines where consumers can enter their memory cards or floppy disks or optical discs, decide how many prints they want, and pick up their photos in about an hour for 24 cents each for 4x6-inch prints. The quality is excellent.