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Digital Photography

Introduction
How Traditional Cameras Work
Advantages of Traditional Photography
Disadvantages of Traditional Photography 
Advantages of Digital Photography
The Digital Difference
Quality Questions
Why Go Digital?
Monitor Calibration
Printing Resolutions
Cropping
Composition

Introduction

Some people may be experts in the field of emulsions, f-stops and exposure settings, but maybe they don't have as firm a grasp on computers. Things like RAM, floppy discs, or bit depth don't interest them as much. On the other hand, there is an equally large number of people who know lots about computers and how much RAM their system has, but need to know more about the world of photography. Some photographic tricks of the trade are given, but in a way a computer guru would understand. 

With traditional photography, an image can be judged on it's own merit. It's good, or it's not . . . . . and that's pretty much it! 

With digital photography, a screen image cannot be judged on it's own merit because that image is only one part of a larger system. It's one link in a chain. Other links in the digital "chain" are the camera (or scanner) that digitizes the image; the CPU that processes the image, the monitor that displays the image, and the output device that prints the image. A bad or inaccurate screen image means there's a deficiency in at least one link of the chain. This emphasizes the need for having a "calibrated" system in order to make effective image quality judgments. There are numerous techniques, programs and devices available to help calibrate your system so that what you see on the screen matches well with your output. Calibrating your monitor is a critical step in this process. 

How Traditional Cameras Work

With a traditional camera, light comes through the lenses and strikes the emulsion, or special silver halide coating, on the film. The brighter the light, or the longer the film is exposed, the darker the image. The film is "developed" using chemicals, creating either a negative (where light parts of the image show as dark, and dark parts show as light) or a slide positive. Prints are then made from the negative.

Advantages of Traditional Photography

The 35mm camera is still the standard for high-quality photography, providing the best resolution at an affordable price for the entry-level user to the professional photographer. Traditional film-based photography has become so affordable, portable and easy, taking pictures does not have to intimidate even the most novice user. 

The latest in one-touch cameras and advanced technologies such as APS (Advanced Photo System) make photography accessible to everyone, allowing amateur photographers to take high-quality photos without the complication of figuring out focus, f-stop and other unlimited terminology and techniques. However, the professional photographer can still take advantage of other technologies that provide control over every element of taking the perfect picture.

Disadvantages of Traditional Photography

Despite all the physical controls a photographer can have over the camera and development of film, traditional photography does not allow the same flexibility and immediacy as digital photography. With a traditional camera, the photographer has to wait until the film is developed to know whether or not the picture is acceptable. A photographer could waste a lot of expensive film, developing costs, time and energy trying to take the perfect picture with a traditional camera. 

Advantages of Digital Photography

Affordability. With digital photography, there are no film costs or processing expenses (paper, chemicals or development costs). If a user makes a mistake or just does not like the image that was taken, the reusable PCMCIA cards or digital film allows the user to erase the picture and simply reshoot it.

Communication. Digital photography makes communication a simple process. A photo can easily be saved to a digital format, put into an Internet Web site, sent as email, or even included as part of an electronic postcard sent to friends from far away.

Control. Digital cameras, combined with image manipulation software, let users resize, rotate, cut and paste, recolor, and otherwise manipulate their photos.

Deletion. The PCMCIA cards, or digital film, standard with digital cameras allow users to immediately determine if a picture is appropriate and simply delete it to make room for another picture.

Duplication. The image can be duplicated over and over without any degradation of picture quality.

Ease of use. With digital photography, there's no fuss, no muss. If a photographer doesn't have time or space or interest in mixing chemicals, the same effects can be achieved using a computer as a digital darkroom.

Image storage. PCMCIA cards, or digital film, allow users to store anywhere from 18 to 3,000 images at one time depending on the resolution of the image and the compression used.

Immediacy. A user can snap a photo, immediately see it on the digital camera's LCD screen, then instantly transfer it into a computer using a serial or parallel cable or removable PCMCIA cards. Digital images can be produced immediately, either printed or electronically distributed over the Internet.

The Digital Difference

Digital cameras "paint with light" in a similar way, using a lens, aperture and shutter. But digital cameras use their electronic image sensors (known as CCDs, or charge-coupled devices) and signal processing technology to convert the light into electronic or digital information. This information (the image) is then compressed so many images can be saved onto the camera's storage device, such as a removable hard drive or memory card. Once saved, it can then be transferred to a computer for manipulation, printing, transmission to another computer via modem or archival storage. 

In place of conventional film, 1MB of internal memory can store up to 18 images and can store up to 72 images with an optional 4MB compact flash memory PCMCIA card. An optional 170MB hard disk drive PCMCIA card makes it possible to store up to 3,000 photos at 832 x 608 resolution. 

Unlike conventional film, the PCMCIA cards are reusable once the images have been downloaded and erased.

Once the image is in the computer, the user can manipulate it with image manipulation software, like Adobe Photoshop.

Quality Questions

Digital photography is suited for many uses, but users should not expect Ansel Adams-like print quality from entry-level models. These cameras are best used for small photos, such as Web images. Traditional film cameras, especially large format cameras, are better suited for large, detailed portraits.

Digital cameras have a narrower exposure latitude than film, and at present, image quality is still lower than that of film-based photographs. The cost of digital imaging equipment is still high, and additional equipment (like a personal computer) is often needed to view the images.

But digital photography is evolving, just as desktop publishing did in the 1980s. Desktop publishing (DTP) was once "good enough" for newsletters, then became widely used for magazine publishing. Digital cameras are following the same arc in enhancing quality, while lowering costs.

Why Go Digital?

Digital photography is not a replacement for traditional photography, but an additional tool. Think of a toolbox: most people have both a flathead and a Phillips-head screwdriver in it. One is no better than the other, but each has a different application.

Monitor Calibration

The basic approach to calibrating a monitor is to acquire and print an image and then adjust your monitor so it matches that image as closely as possible. There are technical reasons why you can't get a perfect match, but the closer you can get, the more accurate your daily work will be. 

A monitor's "bit depth" is another characteristic that will affect the perception of image quality on-screen. Each pixel on the screen is composed of three separate dots of color -- red, green and blue. Your brain "sees" them as a single colored dot. Monitors can display different bit depths, and the greater the bit depth, the more shades of color the monitor can display. Typically, monitors can display 8 bit color (256 shades), or 16 bit color (over 65 thousand shades) or 24 bit color (over 16 million shades). To display photographic quality images on screen you need to be working with 24 bit color. The trade offs for working at this bit depth are slower image processing and the need for more memory on your video card. It's not uncommon for those working with large photographic quality images to use accessory video and graphics cards with extra memory and accelerated image processors. 

Having a calibrated monitor and using 24 bit color provides the necessary environment for working with high quality images using sophisticated image editing software, however, 24 bit color isn't necessary for all projects. For many projects, 8 or 16 bit color may actually be preferable. For example, most internet pages (like the one you are reading) are designed in 256 colors(8 bit). This de facto standard has designers turning their possible monitor colors down from millions to 256. Setting your monitor like this can greatly improve the performance and re-draw speed of your computer. You'll have to make that judgment and equip yourself accordingly depending on your needs. 

Besides monitor calibration and bit depth, other variables to consider in a monitor are size, image sharpness, compatibility with your computer system, distortion, color spectrum of display, resolution, and controls available. All of these factors will affect the digital image displayed on your computer. 

Printing Resolutions

Understanding resolution is important. Resolution affects the quality and file size of your images. Select the resolution or picture quality setting on your camera based on your intended output. Example of camera picture quality settings: 

          · Best - 1600 x 1200 pixels 
          · Fine - 1024 x 768 pixels 
          · Good - 640 x 480 pixels 

Minimum Suggested Printing Resolutions

Resolution
Number of Pixels
Size
Maximum Print Size
640x480
307,200
900K
1¾x2½ - inch
800x600
480,000
1.38mb
2½x3½ - inch
1024x768
786,432
2.25mb
4x6 - inch
1156x864
998,784
2.86mb
5x7 - inch
1536x1024
1,572,864
4.5mb
8x10 - inch
2700x1800
4,860,000
14mb
12x18-inch
3000x2400
7,200,000
20.6mb
16x20-inch
3600x2400
8,640,000
24.8mb
16x24-inch
3600x3000
10,800,000
30.9mb
20x24-inch
4500x3000
13,500,000
38.7mb
20x30-inch
4500x3600
16,200,000
46.4mb
24x30-inch
5400x3600
19,440,000
55.7mb
24x36-inch
6000x4500
27,000,000
77.3mb
30x40-inch

Full Frame Pixels Per Inch

Effective MegaPixels
0.31
0.79
1.23
1.92
3.15
3.76
4.92
Image Size
640x480
1024x768
1280x960
1600x1200
2048x1536
2240x1680
2560x1920
2x3½ 183 293 366 457 585 640 731
3½x5 128 205 256 320 410 448 512
4x5 120 192 240 300 384 420 480
4x6 107 171 213 267 341 373 427
5x7 91 146 183 229 293 320 366
8x10 60 96 120 150 192 210 240
11x14 44 70 87 109 140 153 175
16x20 30 48 60 75 96 105 120
20x24 24 38 48 60 77 84 96
24x30 20 32 40 50 64 70 80
Red: Largest recommended print size.

The following chart lists the minimum recommended DPI setting your original should be scanned at to produce the desired print size in your order.

Minimum Recommended Scanner DPI Setting for the following Print Sizes:

Original Size In Inches
2½x3½
3½x5
4x5
4x6
5x7
8x10
2x3 250 DPI 300 DPI 350 DPI 400 DPI 500 DPI 800 DPI
2½x3½ 200 DPI 250 DPI 300 DPI 350 DPI 450 DPI 600 DPI
3½x5 180 DPI 200 DPI 250 DPI 300 DPI 350 DPI 450 DPI
4x5 130 DPI 150 DPI 200 DPI 250 DPI 350 DPI 400 DPI
4x6 100 DPI 140 DPI 190 DPI 200 DPI 250 DPI 380 DPI
5x7 90 DPI 120 DPI 170 DPI 180 DPI 200 DPI 350 DPI
8x10 80 DPI 95 DPI 100 DPI 120 DPI 140 DPI 200 DPI
35mm Slide or Negative 1000 DPI 1200 DPI 1400 DPI 1500 DPI 1800 DPI 2000 DPI

If there is a chance you will have to resize or edit the image, you should either: 

          · Save image in TIF format (if the camera supports it).
                    - or - 
          · Open JPEG in photo editing software and Save As a TIF. 

Only save a JPEG.file once!!! Jpeg. files become more and more distorted every time you save the file. 

Since an image file can be any size at all, we’ll speak in terms of printing resolution, expressed as pixels per inch, or PPI. As you’d expect, "pixels per inch" is just a measure of how "big" the pixels of our images will be on the printed page. For example, a 640x480 pixel image printed at a size of 6.4 x 4.8 inches has a printing resolution of 100 PPI. 

DPI: Equals 'dots per inch'. DPI always represents dots per linear inch on media. It can be used to denote how many dots are used to produce a printed page or DPI can be used to scale a document for scanning to a required resolution or pixel size. As an example if you scan a 4X6 photograph at 150 dpi, the resulting digital image will be 600 pixels wide by 900 pixels long. The math as follows: 4 inches times 150 dpi = 600 and 6 inches times 150 dpi = 900. Using the math in reverse with our 600 by 900 pixel image and printing it at 150 dpi gets us back to our original 4X6 inch print size.
 
 

Cropping

To insure you have the best picture to print you should always get as close to the subject as possible. Cropping a digital photo takes away valuable image data important to printing. So zoom in and keep shooting!  Optical zoom is much better than a digital zoom. If the lens of the camera zooms in to the subject for the photo then the resolution will be good. If the zoom is a function of the camera capturing a portion of the image then the resolution will be lower.
 
 

Composition

Simplify: move in close, have a strong center of interest, a colorful subject and choose a simple background. Control the placement of subject within the frame, have subject off center, use lines to lead viewer to subject, use foreground to frame subject and to add depth try unusual camera angles.  Add energy and depth, use dramatic lighting, early and late in the day, sidelight and backlight. Strong shadows diagonal lines and patterns can fill an image with energy so use foreground to build depth and perspective.

Back to photography tips main page.

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