Digital Cameras

Digital Camera Basics - A primer

Digital cameras are confusing to many new users. The main guide to digital cameras, digital technology, hope to try to give at least some basis to use in deciding which digital camera is suitable for them. When shopping for a digital camera is more useful to know the basi

c conditions, such as white balance, pixel, ppi and dpi mean and how they affect image and print quality. It is also important to know the difference between things likeoptical zoom digital zoom, as well as advantages and disadvantages between storage formats such as Compact Flash (CF), Microdrive, Sony Memory Stick, Secure Digital (SD) and multimedia technologies such as camera interface, USB 1.1, USB 2.0 and Firewire IEEE 1394.

Pixels

A pixel is a contraction if the term PIcture ELement. Digital images are made up of small squares, just like a tile mosaic on your kitchen or bathroom wall. Though a digital photograph looks smooth and continuous just like a regular photograph, it's actually composed of millions of tiny squares as shown below.

Each pixel in the image has a numerical value of between 0 and 255 and is made up of three color channels. So for example a pixel could be 37-red, 76-green and 125-blue and it would then look like this . If it was 162-red, 27-green and 12-blue, it would look like this . There are over 16 million possible combinations using this scheme and each one represents a different color. Computer savvy readers will note that each color in this scheme can be represented by an 8-bit number (byte), so the color of each pixel is defined by three color bytes. This scheme can be expanded, for example to use 16-bits (two 8-bit bytes) for each color. Images using three 8-bit values are sometimes called 24-bit color images. Images using three 12-bit values for color definition are called 36-bit color images, and those using three 16-bit values are called 48-bit color images.

Pixel Count

One of the main ways to express your digital camera manufacturers in terms of pixels. What is the number of pixels that go into making each image. Today, that number ranges from 1 million (1 Megapixel), about 14 million (14 megapixels). One million pixels is an abbreviation MP, and 1MP camera has 1 million pixels and 3MP camera has 3 million pixels. Currently most popular consumer digital cameras have between 2MP and 5MP. 3MP camera can be excellent 4 "x 6" prints and very good 5 "x7" prints. If you plan to do a lot of 8 "x10" prints, then perhaps 4mp or 5MP camera would be better choice. Sometimes the two numbers given, the total number of pixels and effective pixels. The total number of pixels, each pixel in the sensor surface. Edge pixels are usually not used in the final image. Effective pixels number of points that are actually used in the image after the edge pixels are excluded.

	3MP	4MP	5MP
Largest Image (typical)	2048 x 1536	2272 x 1712	2592 x 1944
Print size at 320dpi	6.5" x 4.8"	7.1" x 5.4"	8.1" x 6.1"
Print size at 240dpi	8.5" x 6.4"	9.5" x 7.1"	10.8" x 8.1"

Aspect Ratio

Ratio is the ratio of the length of the camera image. For example, the traditional 35 mm film frame is about 36 mm wide, 24 mm high. This is a 36:24 aspect ratio, which could equally well expressed as 3:2. Some digital cameras use digital images the same proportion. For example, most digital SLR (single lens reflex) camera's 3:2 aspect ratio. However, the video monitor commonly used 4:3 ratio. For example, 800 * 600 monitor display is 4:3 ratio. With this in mind, the majority of consumers to use digital cameras take pictures of the 4:3 ratio.

Sensors

The size of the digital sensor element (corresponding to the size of the camera negative film) is relatively small in all consumer digital cameras are usually about fingernail size - (and a small nail bar!). As I said earlier, 35-mm film frame is 24 mm high 36 mm wide, but most digital cameras use much smaller sensors. The following are some typical digital camera sensor size."Name of the sensors" is based on the old TV in 1950 described the use of control and nobody could understand why the modern digital sensor, because "size use" in fact all of the ideas, the actual area of the sensor. However, these names are widely used, so that it better understand what they are. They are often referred to as a digital camera specifications.

"Name"	Aspect Ratio	Width (mm)	Height (mm)
1/3.6"	4:3	4.0	3.0
1/3.2"	4:3	4.5	3.4
1/3"	4:3	4.8	3.6
1/2.7"	4:3	5.3	4.0
1/2"	4:3	6.4	4.8
1/1.8"	4:3	7.2	5.3
2/3"	4:3	8.8	6.6
1"	4:3	12.8	9.6
4/3"	4:3	18.0	13.5
EOS 10D	3:2	22.0	15.0

Currently, 5 million pixel digital cameras, most of the use of small 1/1.8 "sensor, approximately 7 mm x 5 Haomi. They have an area 25 times smaller than 35 mm film is approximately 9.5x, compared with a small sensor, Canon EOS 10D Digital SLR Article smaller. You want to know, therefore, this cell size, which is a very complex issue. It is clear that a certain number of pixels, a larger sensor (and thus increase the single pixel region) to improve picture quality and less noise. For example, while the Canon EOS 10D camera's sensor able to run a large part of ISO 3200 equivalent (but without image noise) can and the small number of sensors for consumer digital cameras no larger than ISO 400 and the operation, only the sound is too loud. Why, this is the case of treatment for all, to see the title of the entire network image-size issue, my article here

Another factor is the quality of the sensors is often not the case, a number of sensors. Small sensors, as well as any consumer digital camera sensors, you need a program that can read sensor data in real time as a mechanical shutter, called the "turning point" and CCD electronic exposure control. It is more expensive digital SLR cameras using large sensors, often involving different models, full-frame is called - there is no mention of its size, but their design - in this

context, it is used in a mechanical shutter. They can not read and display real-time information came out first so they can not provide real-time digital display or record video. The advantage of this system is that the entire pixel area can intercept light, while transferring a portion of each pixel CCD is used to store charge. Since smaller pixel areas of noise and the transfer of the CCD, not only small, but began to use the battery, pixel size, noise levels are much higher.Therefore, transfers between lines of small consumer digital cameras, the sensor on content than high-class digital SLR camera using a low-quality images, they can do more than save the video clips, and published its own LCD screen, live image display "tricks. Missing a mechanical shutter, but the cameras will also be cheaper and simplify design.

Small sensors mean that short focal length lens, has given more than the sensors or 35mm camera view field. Thus, for example, a typical consumer digital cameras, it may be necessary to use the 7mm lens, so they can adopt, you'll be using 35 mm camera, 35mm focal length lens. This depth of field effects, which means that the majority of consumer digital cameras have a different depth of field. Great if you want to concentrate all the energy is not so great if you want to be a blurred background. This is included in the title of my article in detail the digital depth of field here.

Balance

When the movie you can buy "daylight balanced film" Shooting outdoor or indoor tungsten photography under normal domestic lighting (no fluorescent!) Balanced movies. "If you use daylight film to the bulb image is very yellow. If you use tungsten film in daylight, the picture is very blue. In the film you have the correct" color temperature of light filters, "or the movie right choice.With respect to digital, you can choose the white balance to the light source, so the white-white, not yellow or blue. Under normal circumstances, and the camera automatically sets white balance to decide what to use. But if you know the light source, you can usually set the camera to anyone who can get better results. Most digital cameras are set forsunlight, shade, flash, fluorescent, incandescent light bulbs. Some amanual or custom settings, click on the white card, camera, deliver the kind of rules so that the number of white camera.

Sensitivity

Sensitivity regulation in the digital camera is equivalent to the Board of Film Classification Standards. Almost all digital cameras is its sensitivity equivalent to ISO 100 and ISO 200 Extra Movie Sets. Many people are ISO 400 setting, but most important, and small sensors are very noisy camera images. The sensor is larger, more expensive digital SLR cameras are sensitive to the settings. ISO 400, they have almost no noise, and some can be up to ISO 3200 and ISO 6400's! Few of the camera's ISO setting lower than ISO 100 because noise levels, so it is slower to use ISO 100 with low set-up, there is no real advantage. Many digital cameras have "auto" ISO setting while the camera selects ISO 100, ISO 200, sometimes 400 different standard for light output and the use of the lens.

The digital zoom and optical zoom

Most of the camera has both optical zoom and digital zoom. Optical zoom is the zoom feature.Changes in lens focal length, and the confirmation, because it is larger. Maintain image quality throughout the zoom range. Digital zoom just crops the image to a smaller size, and then extended cut part of the shoot. Digital zoom quality shown by the following examples of the results of large losses. It is almost a last resort if you do not have a camera, you can use a similar work in almost all image-editing program.

JPEG, TIFF and RAW

The size of the digital file corresponding to the image which the camera produces depends on the pixel count. In most consumer digicams each pixel generates 3 bytes of data (so called "8-bit data"). One for red, one for green and one for blue. This means that a 3MP camera, which has 3 million pixels, generates 9 million bytes of data, or 9MB (megabytes). A few cameras can generate extra data for extra quality, and some of these cameras generate files which correspond to 2 bytes of data for each color ("16-bit"), so a 3MP camera which is capable of generating 16-bit data will produce an 18MB image file.

Now these files are pretty big and they can be compressed quite a lot without a significant drop in quality. This is where JPEG (Joint Photo Experts Group) comes in. JPEG is an algorithm designed to work with continuous tone photographic images) which takes image data and compresses it in a lossy manner (this means you do lose some information). The more you compress, the smaller the file but the more information you lose. However, you can reduce file size by a factor of 10 or so and still get a very high quality image, just about as good as the uncompressed image for most purposes. You can reduce the file size by a factor of 40 - or even more - but the image starts to look really bad!

With 10:1 compression the 8-bit files generated by a 3MP camera would be 900Kbytes in size rather than 9Mbytes, which is a big saving with little quality loss. The smaller files take up much less storage space and are much faster to send between computers or from the digital camera or memory card to a computer.

There are also lossless ways of saving files using TIFF (Tagged Image File Format) . These keep all the original information, but at the cost of much bigger files. TIFF files can be compressed in a non-lossy way, but they don't get very much smaller. For example, compare the file sizes for the rabbit image above: TIFF files can also be used to save 16-bit data (those these files are twice the size of 8-bit data files), JPEG files can only save 8-bit data.

Uncompressed TIFF	Compressed TIFF	JPEG at 10:1 compression	JPEG at 40:1 compression
176.1 Kbytes	157.6 Kbytes	17.4 Kbytes	4.5 Kbytes

Some cameras offer a third option, that of saving the actual data generated by the sensor in a proprietary format. Canon calls their version of this "RAW", Nikon call it "NEF". These files are compressed, but in a non-lossy manner. They are significantly smaller than equivalent TIFF files, but larger than JPEGs. Typically they achieve a compression of around 6:1 using 16-bit data, so files are 1/6 the size of equivalent TIFF files. The only disadvantage of these formats is that the image must be converted to either JPEG or TIFF for most software to be able to display them. The conversion is quite a complex process and can be time consuming if you have a lot of images to convert and a PC that's not very fast. Since the RAW and NEF formats contain more information than JPEGs (and in fact often more than TIFF files) you can do some degree of exposure compensation during conversion to JPEG to rescue otherwise improperly exposed images. You can also make white balance corrections during conversion, so if you shot with the wrong white balance, you can fix your error.

Display, Printing, DPI and PPI

When you display a digital image on the screen, only the pixel of the image determines the number and proportion. Department of Public Information and the producer price index (I will explain later), it is not. If the picture is 480Kbyte file, 800 pixels wide and 600 pixels wide, it will appear full-screen image, if you use a 800x600 screen. It does not matter if your DPI is 1 or 1000, or if your price index is 1 or 1000 is 100% correct at all yesterday, showed a display monitor to enter - if some intervention programs. For example, IE6 browser the big picture and to adjust them on the screen. But the ministry and the producer price index continues to ignore.Complex layout programs and advanced image-editing programs can be used in the department and the output price index, taking into account the display images.

So, I say it again. Great way to control someone else's image is displayed on the screen when looking at the photos makes the Internet the number of pixels. If your original image is 1600x1200 pixels may be too high, can be seen in 95% of all the video monitor there. It is also slow to load, you can edit the file. If you want people to use the 800x600 screen shows a clear picture, you have to change the size, or 600x400 pixels (remember the browser window smaller than full-screen display). You resize the image software. All image editing programs can do this.Sometimes it is referred to as "sample" or "cuts." See your image processing software manual data that you want the software.

Producer price index represents the pixels per inch, almost exclusively in print does not display.If the image is 800 pixels wide and 600 pixels high and printed in output price index set at 100 pixels per inch print is 8 inches wide and 6 inches long. If you print 200 PPI print 4 "wide 3" high. Now, printing 200 ppi high-quality, but smaller. Most people would probably agree that the producer price index of about 320 more than you need. Most importantly, it is difficult to see any improvement in picture quality. 240 producer price index is often used, although it is often of high quality. Most people see the quality decline, the producer price index is below the 180th

Department of Public Information, on behalf of dots per inch "on the printer instead of digital assets. It is a measure of how the distribution of the fine droplets of ink can be printed. However, this figure is somewhat misleading, since it is not always the case that the measure, do you think could be ! printer settings, 360dpi, 720dpi, 1440 resolution of 2880dpi and is often found. the difference is small, but at that time the best. Most people do not necessarily distinguish between 360dpi and is usually good. Department does not change the resize the image. producer price indexes. print quality control department (but as I said, over 360dpi you do not see any major changes).

Memory

This is a beautiful little different (not compatible) memory cards used in digital cameras.

• Compact Flash (CF) - the original memory card. 42 millimeters x 36 Haomi x 3 Hao Mi. A more than others, but they all use the high-end digital SLR cameras. Works up to 2GB. There is also a small hard drive (micro hard drives), almost the same shape Card CF (CF card, 5 mm thick)), which is available in capacities ranging from weight of 3.5 pounds to 4GB. Microdrive using inexpensive solid-state card parameters, although this is not a big difference between the currents of about 1GB. 4GB mini hard drive, in fact, cheaper Chaoguo 2 GB, although the card see. Of course, the price changes quickly, these days! CF cards are usually cheaper in general than any other aspect of memory - though this may change. Micro hard drives and CF cards, including their own disk controller, making the camera electronics simpler.

• Secure Digital (SD) - very small - about 24 mm x 32 mm thickness of 2 mm. They are built on the write-protect switch to prevent accidental erasure and certain encryption parameters of much interest to owners of digital cameras.

• Multimedia - the same size, but on lack of features and no encryption option. Some cameras can be used in certain respects, but they are not 100% compatible with SD cards all the requirements.

• Smart Media - thin card reference, but in the absence of a memory controller. Despite its name, they are really stupid!

• Memory Stick - Sony, Sony, only

• Micro - the development and use of Fuji, Olympus and Toshiba - and even more than the Census and Statistics Department. 20 mm × 25 Haomi × 1.7 mm thick

There is no real difference in performance? No, not the case. Lower per-megabyte CF card and have a higher capacity than other models (of course, which may change the time). Most high-digital SLR cameras to use them. The smaller cards commonly used in small consumer digital cameras. There is no reason to select the cell, one species to another, if you have multiple cameras or other devices (MP3 players, for example) can also use the memory card - a more comfortable, they can share cards. It may be very difficult (and / or expensive) to find a real high-capacity cards (1GB and above) outside the parameters of the format, but it does not give most concerned about this digital camera users.

The following table shows the approximate number of shots you can expect to receive aid, low-compression JPEG, using a variety of pixel camera range of different sizes of memory cards, the lowest sensitivity, a typical camera. The exact amount depends on the use of compression chamber, and the ISO speed to use. The higher ISO settings, leading to more noise, difficult to compress, and will therefore lead to greater documentation, reducing graphics card. If you shoot RAW or equivalent format, you can divide these numbers 3. If you're shooting TIFF files you'd like to share this figure eight.

	3MP	4MP	5MP	6MP
128MB Memory	116	87	70	58
256MB Memory	232	174	140	116
512MB Memory	464	348	280	232

Digital Camera Interface

After getting the pictures stored in camera memory, you need a computer on your way! There are several ways to connect digital cameras to personal computers and external smart card reader.

• sequence - the first digital camera has a serial interface, but not using the camera, because it is very slow

• USB 1.1 - USB Product is the first of a wide range of methods of high speed transfer of data from the camera. This is the theoretical transmission speed of up to 11 Mbit / s (note that this is a trillion trillion bits)

• one USB 2.0 - the development of a USB, but also much faster - up to 480 megabits per second. USB device is compatible with USB 1.1 port on PC, but only their jobs and lower data rates.

• IEEE 1394 (FireWire) - Although it is an old USB interface, which was originally only real use of the Apple computer. Its high capacity to deliver speed (400 Mbit / sec), but now found that certain computer, you can add to your card through a plug-in. More common in digital cameras, digital camera, even better than that.

Almost all cameras can be connected to a computer, but sometimes it is easier to remove the memory card from the camera focused on an audience. Although the camera only USB 1.1. If your computer can use the faster USB 2.0 transfer speed of USB 2.0 card reader. Smart card readers are cheap, anywhere 15-40 yuan.

Buy Digital Camera

Unfortunately, there are more discount store dishonest camera than you'll find that almost any other business. The number of popular photography magazine filled with ads for low price ads.But they tell you, you never really get the price of camera. Either of these will increase $ 75 in shipping, or they are "out" model, but they are a more expensive model, of course. Sometimes they will tell you that the ads of the camera, making plastic from Taiwan, but the other $ 50, are able to model proposed by Japan Sometimes, they will ship it'd be a lot of work to send them back the wrong item. Advertisement in a magazine in a store based on the lowest again you can only see that most of the time you regret it.

However, there are reputable discount dealers and photo.net is associated with some people.The dealers provide photo.net 1 through its Web site, adopted the following link for the sale of small packages, so use them if theu what you want a good price. They are honest, their action on advertising, its low freight rates, price and great response from customer service. If they do not go to them, we recommend that they purchase.