digital camera tutorial >> battery

Digital Camera Battery, things to remember

A digital camera battery is by far the most important part in your camera. Your camera’s image quality, zoom performance, memory card and megapixels are useless if your camera isn’t operational. Here are a few key points to consider when buying and using your batteries.

1. Always carry extra batteries.
Cameras consume battery power quickly so bringing extra batteries is imperative. You don’t want the perfect sunset to get away from you because of empty batteries, do you?

2. Switch off your camera when you’re not using it.
Since your camera eats the energy of your digital camera battery, it is only sensible for you to turn it off when you’re not using it. Don’t leave it on when you’re just sitting idly to conserve the power of your battery. Of course, this tip would not apply if you have a compulsion to shoot everything within the vicinity.

3. Use rechargeable batteries
The cost alone of using regular batteries is astronomical if you use your camera everyday. It is better if you use a rechargeable digital camera battery because it is more cost-effective and can be re-used. Besides, buying a charger and four rechargeable batteries is less expensive in the long run.

4. Extract batteries from your camera when you’re not using it.
This is important, especially if you won’t use your camera for months. It eliminates the possibility of battery leakage, which could damage your camera forever.

5. Do not let your digital camera battery get wet.
Remember that water, even water vapor can impair your batteries. So you have to be very careful when you are near water or you’re taking a photo of waterfalls. Make sure that you are a few feet away when taking pictures of running water unless your camera has underwater housing.

6. Refrain from constant playback.
Although it’s great to see the results of your pictures after taking them, it is better to save the viewing time until after the photo shoot. Constant playback consumes the digital camera battery’s power.

With proper protection, your batteries would remain useful for a long time, giving you more opportunities to capture picture-perfect moments.

digital camera tutorial >> The right digital camera for you

Want to buy your first digital camera ? Read this guide first.
Many kinds of digital cameras with different features and models are hovering around the market today. And you need to decide on your choices and pick up the right one that fits your clicking needs. You must have already heard a lot about the top brands such as Kodak, Nikon, Canon, Minolta, Sony, Panasonic, Polaroid, Olympus, Fujifilm, HP, Samsung, etc. You will need to take your pick based on your budget and requirements.
The most important feature is its resolution in mega pixel. In simple language, this figure tells you how much you can expand your picture without parting with its quality. The higher the resolution, the better. But this doesn’t mean that you have to go for the highest available model in the market. Usually people print photos that are sized 4x6 or 5x7 inhes. So for these photo sizes, any camera above 4 mega pixels will deliver great results.
Second feature that you should evaluate is zoom-in capability. Optical zoom and digital zoom are different terms. Optical zoom means actual zoom done by the lenses, while digital zoom simply increases the size of the picture display without increasing any details. Beware of Digital Zoom. This is a technique, which zooms in on a portion of the image by processing the picture and interpolating the image between pixels – a technique which always produces inferior results. In simple terms 3x optical zoom means you can get three times closer picture of the image you see with your eyes. For this reason, optical zoom is better. So consider only the optical zoom as the real zoom-in feature of the camera.
The third important feature is compatibility with other devices. Find out if the camera you are going to buy is compatible with your computer, printer, memory card, USB drive, etc. Cameras have inbuilt flash memory but the space is limited, so you would have to buy external memory cards, popularly known as Secure Digital Card (SDC) and Multi Media Card (MMC).
The next important feature is the size of the screen that provides digital display of the image instantly. These screens were the major reason that digital cameras replaced conventional cameras so fast. The screen gives you the ability to review the image and delete the ones you do not like. The LCD digital camera screens are up to 3 inches in width.
So, go get your first camera and start clicking.

digital camera tutorial 2 >> Noise

What Is... Noise?

One of the major difference between a consumer digital camera and a digital Single Lens Reflex (dSLR) is that the former produces images with a lot of noise when using high ISOs and long exposure times, and the latter is practically noise-free. Noise is apparent by the presence of color speckles where there should be none. For example, instead of a blue sky, you notice faint pink, purple and other color speckles amongst the otherwise blue sky.

Just what is noise and how can we eliminate or minimize it? This article tries to explain all of this in as a non-technical way as possible. [This also means that the explanations may not be 100% technically correct. If you spot any mistake, please email me. Thanks.]

Digital Image

When we hear 'digital' we automatically tend to think of high quality. Digital sound does not degrade no matter how many times you play it. Digital images can be saved forever and will still print in its pristine form.

But the image in a digital camera is sourced from a non-digital component: the CCD or CMOS image sensor. Understanding how light striking the image sensor is converted into digital form makes clear what noise is and why it is present.

From Analog To Digital

An image sensor is typically comprised of a matrix of light sensors. A light sensor can be thought of as simply a device that converts light into an electric charge.

Each square of the image sensor matrix is a photosite, usually with one light sensor 'painted' on it. A photosite generally corresponds to one pixel in your digital image.

When light (photons) strike the image sensor, electrons are produced. These "photoelectrons" give rise to analog signals which are then converted into digital pixels by an Analog to Digital (A/D) Converter.

Causes of Noise

There are a number of sources of noise contamination.

Heat generated might free electrons from the image sensor itself, thus contaminating the "true" photoelectrons. These "thermal electrons" give rise to a form of noise called thermal noise or dark current.

Another type of noise is more akin to the 'grain' obtained by using a high ISO film. When we use a higher ISO, we are amplifying the signal we receive from the light photons. Unfortunately, as we amplify the signal, we also amplify the background electrical noise that is present in any electrical system.

In low light, there is not enough light for a proper exposure and the longer we allow the image sensor to collect the weak signal, the more background electrical noise it also collects. In this case the background electrical noise may be higher than the signal.

So why is using a larger image sensor better?

Each photosite itself generates electrical noise that can contaminate its neighbor. In a larger image sensor, the photosites can be physically further apart and thus be less affected by that contamination.

A larger image sensor also means that the photosite can be larger, thus have a larger light gathering capacity. It is therefore able to generate a larger signal to noise ratio.

That is why a digital camera with 6 million pixels crammed into a 1/1.8 in. image sensor has more noise (especially at high ISOs) than a 6MP digital camera using the much larger half-frame (APS-sized) image sensor.

In-Camera Reduction Of Noise

Camera manufacturers have therefore incorporated in their firmware noise reduction algorithms that kick in when a slow shutter speed and/or high ISO is used to try to reduce the noise. Depending on the quality of the algorithms, these work only to a certain extent: they do not completely remove all noise and the smoothening effect of noise reduction is frequently accomplished at the expense of fine image detail.

Noise Reduction Software

There is a number of image editing software that can be used to reduce noise in a digital image after you have taken them. Your image editing software may already have such an action, or you may download one free from the Internet. The better noise reduction software applications (such as NeatImage, Noise Ninja [review] and NoiseWare Pro) can take a long time to process one image and so may not really be a viable solution if you have lots of pictures with noise. They have their place though in a photographer's toolbox and for that one photograph that you have to take with noise or else miss an incredible shot, these software applications are your perfect noise reduction tools. In fact, no photographer should be without one.

Why Are dSLRs Practically Noise-Free?

If it has not yet occurred to you to ask it, you should. Really, why are dSLR images almost noise-free? The answer is simple: a larger image sensor!

See, with a larger image sensor, each pixel can be larger and each photosite can be a bit further away from its neighbor (of course, there is an optimum distance beyond which we'll have 'gaps'). This extra distance is often enough to prevent signal leakage from one photosite onto another -- hence much less to almost no noise!

Hurrah for Bigger Image Sensors!

Why therefore do camera manufacturers not use the bigger image sensors in consumer digital cameras? A bigger image sensor means the need for a bigger lens. Unlike film that can capture light incident on it at an angle, an image sensor requires that light falls on it straight on. Bigger lens add costs, need a bigger body, etc. etc. You get the idea. You quickly end up with a camera body the size of a... dSLR.

The biggest image sensor on a prosumer digital camera is 2/3 in. sized at 8.8 x 6.6 mm (though most of them now use an improved 1/1.8 in. type). We wait for the day when an APS-sized image sensor is used in a prosumer model!

The next size down is 1/1.8 in. (sized at 7.2 x 5.3 mm) and is prevalent in most of the 5MP, 6MP and 7MP consumer digital cameras today.

Notice how camera manufacturers have 'squeezed' more megapixels into the same 1/1.8 in. image sensor. That is one reason some people say that a digital camera at a lower megapixels resolution gives images that are more noise-free than one at a higher megapixels resolution -- on the same size image sensor. More megapixels on the same sized image sensor means the pixels are closer together -- thus more noise. Of course, better in-camera noise reduction algorithms in the newer digital cameras can counter this tendency toward more noise to a certain extent. Photographers must balance the advantage of higher megapixels versus more noise (albeit reduced with the in-camera noise reduction algorithms), although camera manufacturers leave us with few choices as they all move to the higher megapixels image sensor to compete with one another.

The dSLRs have image sensors that are much larger than 2/3 in. Some dSLRs have an APS-sized (or, 'half-frame', approx. 23.7 x 15.6 mm) image sensor.

When we talk about a 'full-frame' image sensor, it is in relation to a 35mm film and is therefore sized at 36 x 24 mm. Compare these with the 2/3 in. image sensors in prosumer digital cameras sized at 8.8 x 6.6 mm, and you'd agree that the size difference is indeed substantial. No wonder dSLRs produce practically noise-free images.

Are we ever going to see bigger image sensors in prosumer digital cameras? Bigger sensors mean bigger lenses mean more expensive cameras. So that is why most of the work being done now is focused more on improving the small image sensors and writing better noise reduction algorithms. However, we believe it is inevitable for the APS-sized image sensor to eventually move down to consumer digital cameras, starting with the prosumer models.

What Can You Do?

There are a number of things to remember about noise:

• A slow or long exposure introduces noise.
• A higher ISO introduces noise.
• Noise Reduction Software will clean up the noise in some images, and sometimes it's done well enough that you can't really tell the original image had unacceptable noise level in it.
• If you must have the option of using high ISOs (e.g. to capture fast action in low-light situations), then get a dSLR. Since many amateur photographers purchase 35mm SLR cameras today (especially since they are relatively cheap), I don't see why they should not be able to use a dSLR as easily. The only roadblock to owning a dSLR for many today is its high price, though even that is steadily coming down as competition heats up among camera manufacturers. We can now obtain a dSLR for under $1000, including the lens.

Noise is a fact of life in consumer and prosumer digital cameras, and is going to stay with us for some time longer until camera manufacturers engineer better and small noise-free image sensors. Until then, what can you do to reduce the amount of noise in your digital images?

1. Avoid slow or long exposures.
2. Avoid using high ISOs.
3. When comparing digital cameras, all things being equal, favor the one with the larger image sensor. For example, Camera A may be 3MP using a 1/2.7 in. image sensor (sized at 5.3 x 4.0 mm), while Camera B may also be 3MP but uses a larger 1/1.8 in. image sensor. Camera B will probably produce images that have less noise than Camera A.
4. Purchase a noise reduction software. This will allow you to take pictures and not miss some great shots. You'll find that a good noise reduction software usually does a pretty good job of 'cleaning' up the noise to an acceptable level in most of your noisy images.

Here is a comparative illustration of the approximate sizes of the currently most popular image sensors:

Image Sensor	Size (approx.)
full frame	36 x 24 mm
half frame (APS)	24 x 15 mm
2/3 in.	8.8 x 6.6 mm
1/1.8 in.	7.2 x 5.3 mm
1/2.7 in.	5.3 x 4.0 mm

digital camera tutorial 1 >> Histogram

"Goldilocks and the Three Histograms"

More and more consumer digital cameras are now including a histogram display either during the Record mode or in the Playback mode. This tutorial explains just what the histogram is and how you can use it to ensure a correctly exposed picture.

What The Histogram Is

The histogram is simply a graph that allows you to judge the brightness of an image. You can think of the area under the graph as comprising all the pixels in your captured digital image. The left side of the histogram depicts how many "dark" pixels you have captured; the right side, how many "bright" pixels you have captured.

Let's look at the histograms of three pictures I took to illustrate how to read and use a histogram:

The left histogram indicates you have most of your pixels toward the dark. The pixels also touch the left edge, indicating underexposure. If Goldilocks had stumbled onto this histogram while taking a picture, you can hear her saying something to the effect: "This picture is too dark."

The right histogram indicates you have most of your pixels toward the highlight. The pixels also touch the right edge, indicating overexposure. Looking at this histogram, Goldilocks would wail something to the effect: "This picture is too bright."

The middle histogram depicts a correctly exposed picture with the pixels mostly in the middle, i.e. neither too dark nor too bright. (Goldilocks: "This picture is just right.") Notice a few pixels touch the dark edge, so we should also expect a few very dark spots in the picture.

Perhaps the best way to understand the histogram is to look at the sample shots that go with the above three histograms.