Smart, Safe and Intelligent Zoom

Realizing that digital zoom is not really a good thing because it negatively affects image quality, camera manufacturers have introduced a new type of digital zoom variously called “Smart Zoom” (Sony), “Safe Zoom” (Canon) and “Intelligent Zoom” (Panasonic and others). Smart/Safe/Intelligent Zoom (let’s collectively called them Intelligent Zoom, or iZoom for short) can be viewed as an “ethical” digital zoom which avoids interpolating the image and so avoid degrading image quality. iZoom works only if you select an image size smaller than the full available image size. So, for example, if your digital camera is capable of producing a 12MP image, Smart Zoom is available only if you select to save your images as 7MP or less. In other words, with this particular type of digital zoom, the MP resolution decreases as you ‘zoom’ — in other words you are just cropping the center of the image (without enlarging and interpolating back to the original resolution).
Say, your digital camera is 12MP and you select to save your images as 10MP. So, in effect, you are forfeiting 2MP of image data (extracted from all over the image area) that the digital camera’s sensor has captured and now has to throw away [you hope the camera makes the right decision and does not throw away important image data]. Enter iZoom that says, “Hey, instead of throwing away 2MP of good data from all over the image area, why don’t I crop out all the pixels starting from the outside perimeter? When I’ve cropped out 2MP of image data all around, I have 10MP left over and that’s what you want, right?” Notice, the 10MP image does not have to be interpolated and enlarged back to 12MP as traditional digital zoom does (because you elected to save it as 10MP, remember?). So, in effect, you’ve basically more or less retained the same image quality but you have to save your resulting simulated zoomed image in a smaller image size. Of course, if now you turn around and enlarge it in post-processing, you will be limited to what a 10MP image can be enlarged up to without image degradation.
I call iZoom “ethical digital zoom” because it is not made available at full image size — this would cause image degradation. The smaller you elect to save your image, the more iZoom power you have available (folks, you’re basically just cropping the image without re-enlarging, which you can also do at any time in post-processing).
So, our recommendation still holds. If you want zoom power, only optical zoom matters! iZoom is the better form of digital zoom, but what you gain in simulated zoom power (again, you’re just cropping), you lose in image size. There’s no free lunch.
Again, don’t buy a digital camera based on digital (traditional or inteligent) zoom. Always compare optical zoom with optical zoom. If you are comparing 2 digital cameras with the same optical zoom, but one has intelligent digital zoom and the other has traditional digital zoom, then the intelligent zoom has a slight advantage. But personally, I wouldn’t even look at that because there are a lot more important features to differentiate the cameras.

Optical Zoom vs. Resolution

What about optical zoom vs. resolution? Sigh! Now you all know that we cannot and should not be comparing apples and oranges, but we still try. The megapixels resolution of a digital camera can be thought of as the number of pixels available to capture an image.
Do not compare optical zoom with megapixel resolution because optical zoom is not megapixel resolution-dependent. That is, the resolution of your final image does not change no matter how much you zoom in. If your digital camera is 15MP and has a 12x optical zoom lens with focal length of, say, 30-360mm, then at 30mm, your image is 15MP and at 360mm, it is still 15MP. With digital zoom/enlargement, the megapixel resolution decreases as you “zoom” in digitally. If you now bring the cropped image back to the same 15MP size, then there are pixels interpolation and the resulting image suffers in quality.
We always disable digital zoom in camera, choosing to do our own cropping and enlarging in an image editing software.
Optical vs. digital zoom? There is no contest. Only optical zoom matters when selecting a digital camera.
What we are really trying to say is this: do not compare. You’ve got to decide what is more important to you: resolution or optical zoom? If the answer is both, then find a digital camera that has both. It’s that simple. If it’s outside your pocketbook range, then choose a digital camera for what is more important to you.
One important consideration with regards to resolution is important to make here: don’t be fooled by the high megapixel resolution advertised for a camera. A compact digital cameras with around 6-8 MP produces perfectly beautiful images for most point-and-shooters. Go higher and overall image quality seems to get worse instead of better. It has to do with pixel density: cram too many ever tinier pixels close together onto a tiny image sensor and all kind of image quality issues come up, including the all important noise. I am here talking about compact digicams with tiny sensors (usually sized at 1/2.3-in. to 2/3-in.). The micro Four Thirds and APS-C digital cameras have much bigger sensors and the megapixel resolution can safely go as high as 24+ MP.

Megapixel

A megapixel refers to one million pixels, and is commonly used in reference to digital cameras as an indication of resolution capability. A pixel is a tiny square on a computerized display that is so small it appears as a dot. The display screen is a solid grid of these squares or dots, which can be easily seen with a magnifying glass. The more pixels or dots that make up the display screen, the clearer the resolution or image will be. Greater numbers of dots or pixels allow for more refinement of the image, which results in higher, truer image replication.

When it comes to digital cameras, the picture quality capability is measured in megapixels. For example, a 3.1 megapixel camera can take pictures with a resolution of 2048 x 1536, which equals 3,145,728 pixels. That is, the resulting image will be made up of 3.1 megapixels, or over three million dots. Printers measure quality in DPI (dots per inch). A printer capable of only 300 DPI will not print the 3.1 megapixel image in its native high quality. It's simply not capable of reproducing the fine detail. Instead the image may appear grainy. If you wish to print photos, be sure the printer is well suited to the capabilities of your digital camera.

The number of megapixels required to suit your needs depends on what the camera will be used for, and what size prints are desired, if any. The higher the resolution —- or greater the megapixels —- the more flexibility the camera will have in terms of being able to deliver high resolution prints in large sizes, such as 8x10.
For those who do not wish to print digital photos at all, but prefer to view images on the computer or television display, purchasing a high megapixel camera is not required. Even 1.5 megapixels will suffice. That said, most cameras as of fall 2005 are 3.1 megapixel or better.
If you are planning to print pictures in sizes up to 8x10, experts recommend a camera with 4-5 megapixels, or a resolution of about 2500 x 2000. For prints up to 12x16, look for resolutions of 3200 x 2400 or better, which translates to a 6 megapixel camera or greater. As a comparison, many professionals use 11 megapixel digital cameras for maximum resolution and clarity even in large printed displays. If you don't plan to print enlargements, paying for more megapixels than you need will be a waste of money.
Aside from the megapixel rating of the digital camera, the amount of internal memory and type of flash card can make a big difference in convenience and long-term cost. Larger internal memory allows for more flexibility, as does the ability to use flash cards with higher capacities, though those with lower capacities will be less expensive.

What Is Zoom on a Camera?

The zoom capability on today's modern cameras is probably one of the easiest features to learn and the most fun for the new photographer. With the latest digital cameras, photos of a distant object can appear as if they are much closer.

Zoom Ability

• The built-in zoom feature of a self-contained digital camera will be measured by its magnification power, labeled as 3x, 6x or even 12x. The labeling shows the zoom ratio provided by the camera. Note, too, that similar measurement zooms may differ in performance between cameras. Depending on the construction, different materials and camera designs will produce marginally different pictures between brands. Also one brand may have a wider angle lens then another with the same zoom capability. The result, again, is different photos.
  Also, some cameras use optical zoom, which is the traditional magnification caused by moving glass lenses inside the camera. Others offer digital zoom, which uses a computer algorithm to guess what a zoom image should look like. The optical image is better on a quality basis.

Zoom Focal Length

• Every camera, from digital to single-lens reflex (SLR), has a focal length. This is the distance from the camera lens' optical center to the focal point. In digital cameras, the focal point will be the sensor that picks up the image being photographed. The longer the focal length, the bigger the magnifier, such as 6x or 12x.

Fixed vs. Adjustable

• Most cameras with a static, built-in lens (nondetachable) have a fixed focal length. Those with a lens that adjusts or can be changed a longer zoom lens would be adjustable.

Capability

• A switch on the camera's body triggers the zoom capability on digital cameras, pushing the lens out from the camera (increasing magnification) or drawing it back (reducing magnification). In SLR, or manual, cameras, adjusting the zoom is done by hand.

Some Problems with Zooming

• Higher zoom abilities can compromise photo quality. The first issue will be the shake factor. The longer the lens, the more vibration that can takes place, making it harder to take a clear picture. Good cameras compensate with anti-vibration features. Second, maxed-out zoom shots degrade the edge of a photo and suffer from less light entering the lens. A faster shutter speed or artificial light offsets this effect.

How Fast Is Your Zoom?

Often, lenses may be marked with a range of f-stop numbers, such as f3.8-f4.5, which means that it has an aperture of f3.8 when set at its greatest wide angle, and f4.5 when shooting at its maximum telephoto. The lower the number, the faster the corresponding shutter speed. Most digital camera zoom lenses are on the slower side, like f3.5 or f4.5. Faster lenses, like f2 or f2.8, are great for shooting in low light; the downside is that they're generally bigger and heavier (they have more glass) and often cost more.

Using Your Zoom Lens Creatively

Besides moving your subject closer or farther away, your camera lens also changes perspective as you zoom. At telephoto, the foreground and background will appear much closer to each other, as though they're compressed. But at a wide angle, the foreground and background will look like they're far apart. Wide angle can distort close-up subjects in interesting ways.

Try this experiment: Stand with your main subject about 6 to 8 feet from your lens. Then, without moving closer or farther from your subject, take a series of pictures using different zoom settings, from wide angle to telephoto. This one experience will give you a more intuitive understanding of your zoom lens than any listing of numbers. As you get to know the characteristics of your zoom lens, you will gain more control over your photography and have even more fun with it.

Interchangeable Lenses & Some Zoom Lens Drawbacks

Interchangeable Lenses

Digital cameras aimed at beginners and intermediate users typically only offer a built-in lens. Most digital SLR cameras, however, can make use of interchangeable lenses. With a digital SLR, if your first lens doesn't have the wide-angle or zoom capabilities that you want, you can purchase additional lenses that provide more zoom or better wide-angle options.

Digital SLR cameras are more expensive than the point-and-shoot models, and they're usually aimed at intermediate or advanced photographers.
Some Zoom Lens Drawbacks
Although choosing a point-and-shoot camera with a large optical zoom lens is desirable for many photographers, it sometimes presents a few minor drawbacks.

    Noise. Some beginner-level, inexpensive cameras suffer from lower image quality because of noise when the lens is extended to the maximum zoom capability. Digital camera noise is a set of stray pixels that don't record correctly, usually appearing as purple edges in a photo.
    Pincushioning. Maximum zoom also sometimes causes pincushioning, which is a distortion where the left and right edges of the photo appear stretched. Horizontal lines appear slightly curved toward the middle of the frame. Again, this problem usually is limited to beginner-level, inexpensive cameras with large zoom lenses.
    Slower shutter response time. When using the maximum zoom magnification, the shutter response time sometimes slows, which may cause blurry photos. You also could miss a spontaneous photo because of the slower shutter response. It simply takes the digital camera longer to focus on the image at the maximum zoom setting, which explains the slower shutter response time. Such problems are magnified when shooting at maximum zoom in low light.
    Requires a tripod. Using a long zoom lens can cause increased camera shake. Some digital cameras can correct this problem through image stabilization. You also can use a tripod to prevent blurry photos from camera shake.

Understanding Zoom Measurement

When looking at specifications for a digital camera, both the optical and digital zoom measurements are listed as a number and an "X," such as 3X or 10X. A larger number signifies a stronger magnification capability.
Keep in mind that not every camera's "10X" optical zoom measurement is the same. Manufacturers measure the optical zoom from one extreme of the lens' capabilities to the other. In other words, the "multiplier" is the difference between the smallest and largest magnification measurements of the lens. For example, if a 10X optical zoom lens on a digital camera has a minimum magnification equivalent to 35mm, the camera would have a 350mm maximum zoom. However, if the digital camera offers some additional wide-angle capabilities and has a minimum 28mm equivalency, then the 10X optical zoom would only have a maximum zoom of 280mm.
The zoom range should be listed in the camera's specifications, usually in a format similar to "35mm film equivalent: 28mm-280mm.” In most cases, a 50mm lens measurement is considered as "normal," with no magnification and no wide-angle capability.