The ISO numbers in digital cameras represent the amount of sensitivity of the image sensor. ISO stands for International Standards Organization. This organization established the standard used by sensor manufacturers to determine the sensitivity to light of a specific ISO setting.
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Digital Camera ISO
Digital Photography – A Visual Language
Photography is a visual language. By learning and applying the visual language of photography, you can become a good, and maybe even a great photographer, regardless of what equipment you are using.
The Visual Language of Photography
So just what is this visual language?
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Why Go Digital?
Why would you want to use a digital camera?
Remember those instant Polaroid cameras … they were so great because you could see the pictures minutes after taking them. They were kind of bulky and film wasn’t cheap, but they were still very popular.
Then along came the 35mm cameras. Less bulky,crisp picture quality and those vibrant colors. People soon were switching, especially when 35mm prices became quite affordable. So is it time for another switch?
Digital cameras have come of age and are rapidly replacing film cameras as the camera of choice. You get the instant picture advantages of the polaroid days and the quality of the 35mm.
Digital cameras can give you photographic prints of high quality … digital photos have exceptional clarity and vibrant colors. Even a novice can produce professional quality pictures. And digital is much more forgiving than film.
Using simple photo editing software you can remove red-eye with a few mouse clicks, crop out unwanted background items, or adjust color and contrast to produce a truly outstanding photograph. Traditional film-based alternatives do not allow for this kind of photo correction unless you are a darkroom wizard or scan your film into digital images.
Another advantage that digital photography offers is greater efficiency. When you take a photo with film, you are committed to each and every shot. Each shot uses a frame of film. When you develop the film, you pay for every print, even the bad ones.
You have probably spent money on pictures of blurred thumbs, kitchen floors and that “accidental first shot” you took while making sure the film was loaded into the camera. Digital cameras allow you to preview every shot before deciding which ones to print.
This eliminates spending money printing poor quality and error-riddled pictures. If you take a great deal of photos, or don’t like paying for useless snapshots, a digital camera can save you a lot of money.
Digital photography also allows for far greater flexibility in use. Digital photographs are far more portable than traditional snapshots. You can share them with friends and relatives instantly via email. You can post them online to be shared with others, too. Digital photographers don’t worry about writing “Photos: Do Not Bend” on envelopes and hoping their photos arrive undamaged.
And digital photos allow for additional storage opportunities. A photo album is great for your old Polaroids, but what happens if it is misplaced or damaged? Digital photos can be safely stored on CD-roms or online, where they will always be immediately available for viewing and/or printing.
The graphics files of your digital photographs can be easily converted to other uses also. You can transform them into T-shirt iron-ons, put them on coffee mugs and create other novelty items using inexpensive photo software.
Considering the potential long-term cost savings and the greater flexibility offered by digital photography along with the improved picture quality the cameras offer, it becomes clear that anyone interested in taking photos should make the switch. It may be hard to put aside that old camera but there’s no reason to continue snapping film-based pictures and being disappointed with the results.
With a digital camera you can produce excellent photos. And if you don’t, then you won’t need to buy them or keep them. If you haven’t already switched to digital photography, there’s no better time than now. The advantages to digital photography are simply too overwhelming to ignore.
Here’s to better photography…
Al Hannigan
Digital Camera Image Sensor
An image sensor is the digital equivalent to film in a conventional camera.
Unlike film, however, the image sensor is built into the digital camera and cannot be changed for different situations.
The most common sensors used today in digital cameras are the CCD (Charged Couple Device) and the CMOS (Complementary Metal Oxide Semiconductor).
If you want to know which kind your camera has, go to the specifications page in the owner’s manual.
The full details on how image sensors work is beyond the scope of this lecture series, but a few things that do affect your images are important, and that is what we’ll be covering here.
Complex Technology…What’s a Pixel
Example of image area enlarged 1600 % to show pixels
Images created with a digital camera are made up of pixels, which are small squares of color ( or shades of gray in the case of a B&W image ). The camera’s image sensor must convert the light it is exposed to into these pixels to render an image.
Image sensors are comprised of millions of tiny photo sensors (pixels) that record the intensity of light as an electrical charge. It then converts this charge into digital information that is used to create the final image.
The data must go through various stages of interpretation and conversion, but for most practical applications it isn’t necessary to understand all the specific details.
It is important, however, to recognize that image quality can be affected by this technology, and some cameras do a better job than others.
Sensor Sizes in Digital Cameras
One factor to consider is sensor size. In most digital compacts, image sensors cover only about 4% to 7% of the image area of 35mm film. Digital SLR image sensors will generally cover from 33% to a very few that cover 100% of the 35mm film area.
Since larger sensors have larger pixels, they can record more detail and produce smoother images. Generally, larger sensors capture images with less noise and greater dynamic range than smaller sensors.
When choosing a digital camera therefore, it is important to consider the actual size of the sensor as well as how many mega pixels the camera has. A 5 megapixel digital compact camera will not necessarily have the same quality as a 5 megapixel DSLR (digital single lens reflex).
The sensor size has what is referred to as a crop factor, or a focal length multiplier. This is a number that relates the smaller sensors to a full frame 35mm area. It is one of the reasons that a full frame 12 Mega Pixel DSLR will usually create a higher quality image than a 12 MP camera that does not have a full frame sensor.
NOTE: Don’t confuse larger ‘sensor pixels’ with larger ‘image pixels’. A larger sensor pixel can collect more detail, and produce finer images. This is good. Large pixels in the photo image mean less quality and can cause pixelation…this is when you begin to see the pixels in your image. This is not good.
To use an analogy, say you have 5 million blocks and they need to fit into a .25 inch x .375 inch area (size of a typical compact digital camera image sensor). The blocks would need to be small enough for all 5 million to fit.
Now let’s say you have a 1 inch x 1.5 inch area (approximate size of 35mm film) to fit the same number of blocks into. Having more area to work with would therefore allow each block to be made larger.
The same idea holds true for sensor pixels. To fit 5 million pixels into a smaller sensor, each pixel must be reduced or compressed. This compression can reduce the amount of data each pixel can gather. This is why pixel count should be only one of several factors you compare when considering image quality.
It would be important to understand this technology for anyone doing a serious review of various digital cameras. But for most photographers it is something you need to be aware of, if only to realize that pixel count alone is not enough to assure you of high quality images. Comparing final image results is the best way to judge a camera’s performance.
Image Sensors Exposed
When you take a picture, you are exposing the image sensor to light. The data collected by the sensor’s pixels are recorded, analyzed and processed to yield a digital image that looks similar to the scene you photographed.
This complex operation is another factor which affects final image quality, and varies from one camera to another. Such matters as noise, color accuracy, sharpness and tonal range, to mention but a few, are all affected by this process.
So again, the importance to you as a photographer is best seen by comparing final results. Fortunately, there are some excellent review sites that do this for you. Therefore, you don’t need to actually test every camera yourself. But knowing a little about sensors and pixels will help you better understand these reviews.
Whenever you want to compare cameras you are considering, or learn more specifics about a camera you already own, just do a search for digital camera reviews on any major search engine to find a list of these review type sites.
You’ll locate some excellent sites that do extensive in-depth comparisons of most of the popular cameras available. They will usually have samples of actual photos taken with these cameras as well, so you’ll be able to see the level of quality each can produce.
Three of my favorites are:
dpreview.com
Steve’s Digicams
Imaging Resource
There are many others for you to choose from, but these are 3 I have used myself and am most familiar with.
Here’s to better photography …
Al Hannigan
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