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.

Digital Zoom

The digital zoom measurement on a digital camera, to put it bluntly, is worthless under most shooting circumstances. Digital zoom is a technology where the camera shoots the photo and then crops and magnifies it to create an artificial close-up photo. This process requires magnifying or removing individual pixels, which can cause image quality degradation.
Most of the time you can perform functions equal to a digital zoom with photo-editing software on your computer after you shoot the photo. If you don't have time for or access to editing software, you can use digital zoom to shoot at a high resolution and then create an artificial close-up by removing pixels and cropping the photo down to a lower resolution that still meets your printing needs. Obviously, the usefulness of digital zoom is limited to certain circumstances.

Optical Zoom

Optical zoom measures the actual increase in the focal length of the lens. Focal length is the distance between the center of the lens and the image sensor. By moving the lens farther from the image sensor inside the camera body, the zoom increases because a smaller portion of the scene strikes the image sensor, resulting in magnification.
When using optical zoom, some digital cameras will have a smooth zoom, meaning you can stop at any point along the entire length of the zoom for a partial zoom. Some digital cameras will use distinctive stops along the length of the zoom, usually limiting you to between four and seven partial zoom positions.

What Is a Telephoto Lens?

A telephoto lens is a camera lens designed to enable people to take long focal length pictures using a lens with an actual length which is shorter than the focal length. For example, a 400mm telephoto lens is not in fact 400mm long, unlike a conventional 400mm lens. There are a number of reasons why people might want to use a telephoto lens, ranging from the need to have a camera which is easier to handle but still capable of long focal length images to a desire to take advantage of specific traits of telephoto lenses.
When people hear the phrase “telephoto lens,” they often think of an extremely long camera lens. Some telephoto lenses are quite long, but this is not necessarily so, and long lenses aren't always telephoto lenses. This term refers to a lens of a very specific construction, not a particular length.
In a telephoto lens, there is a lens element at the front of the camera just as there is with other cameras, but there is a second element in the back of the lens in front of the film which acts to magnify the front lens. This second element effectively increases the focal length of the camera by making it seem as though the first lens is further away than it really is. Historically, a telephoto effect was sometimes accomplished with the use of lenses positioned in front of an optical instrument, but today the structure is built right into the lens.

The primary reason to use a telephoto lens is to take photographs of objects at a distance. A lens with a short focal length cannot take good images of things in the distance. The longer the focal length, the more detail can be seen in the distance. With a telephoto lens, a certain amount of compression also occurs, with more objects fitting into the visual field. As focal length decreases, depth of field widens, which changes the look and feel of the image.
People often want to take images with a long focal length, as for example when someone on the shore wants to take pictures of boats. However, the lenses needed for such photographs can become very long and cumbersome. They make the camera hard to handle and they also put strain on the lens mount and can damage it. A telephoto lens allows photographers to have the best of both worlds in the form of long focal length and a shorter lens.

How Do Zoom Lenses Work on Cameras?

The zoom, or magnification, features on a camera are determined by its focal length. The focal length is the distance between the lens and the camera’s sensor. The greater the focal length, the greater the camera’s ability to shoot a clear, close up image from a distance. Conventional film cameras have only optical zoom, while digital cameras may have both optical and digital zoom features.

Optical zoom lenses are usually considered far superior to digital zoom lenses. A camera with an optical zoom feature is much like any conventional camera. The lens is like a telescope that magnifies the subject and then captures the enlarged image. Digital cameras are manufactured with varying optical zoom capabilities. If someone is an avid photographer or has the desire to take quality photographs from afar, then he or she will want to consider the level of optical magnification on a variety of cameras before choosing one. 

Digital zoom is typically not as effective. In addition, using this feature without understanding how it works can produce some very disappointing photographs. Digital zoom works the same way that cropping an image using photo editing software works. For example, if a person has a photograph that he took at a distance and wants to crop it to enlarge some aspect, he would probably notice that it loses its resolution, resulting in a fuzzy or grainy image. A digital zoom lens does the same thing, but as the image is being captured. Therefore, if someone sees a great shot from a distance and uses the digital zoom feature, he is likely to get a poor image.
Why digital zoom is included is a mystery to some, since the same effect can be achieved using software, which can always be corrected if the outcome is poor. Once a photo is taken using this feature, then what is captured is what the photographer gets. Some people feel that the digital version is a marketing technique intended to make one company’s product seem better than another’s without sacrificing the overhead associated with adding a quality optical zoom feature.

Zoom Lenses

• Conventional film cameras have only optical zoom, while digital cameras may have both optical and digital zoom features. Optical zoom lenses are usually considered far superior to digital zoom lenses. A camera with an optical zoom feature is much like any conventional camera.
  
  
• For everyday hobby shooting, however, it probably isn't necessary to buy such a lens. A mid-range zoom lens with an adjustable focal length will suit just fine for such purposes

Zoom
 

• The fine focus ring is often positioned near the narrow eyepiece end of the zoom monocular. Magnification adjustments are usually made by turning the wider end of zoom monoculars to move the largest lens back and forth.
  
  
• If someone is an avid photographer or has the desire to take quality photographs from afar, then he or she will want to consider the level of optical magnification on a variety of cameras before choosing one. Digital zoom is typically not as effective. In addition, using this feature without understanding how it works can produce some very disappointing photographs.

How Do I Choose the Best Digital Camera Lenses?

When choosing digital camera lenses, you should keep in mind the types of pictures you most often take and the conditions in which you need the lenses to perform. One of the first things you should consider is the type of zoom you want to have on the lens, with regard to both zoom distance and control. You should also ensure you choose lenses with aperture speeds that suit your needs and consider any secondary features you need. Many camera manufacturers use lens mounting systems different from each other, so you should ensure any digital camera lenses you choose can mount onto your camera.

Digital camera lenses are devices that connect to digital cameras to provide improved functionality and zoom features. You should be sure that any lenses you choose provide you with the type of zoom functionality you are looking for. Most lenses have descriptive labels for the power of the zoom, such as “telephoto” and “super zoom.” You can use these descriptions to give you an idea of the zoom quality, but you should also look for quantitative indicators such as “16-35mm” or “50-200mm,” in which larger numbers indicate the ability to zoom in more closely over a greater distance.

Different digital camera lenses can also provide different methods by which you can control the focus of the lens. "Autofocus" systems use mechanisms that allow the camera lenses to adjust the focus of the image automatically. While these systems are often quite helpful, you may also want to be able to adjust the focus manually as well. Most digital camera lenses allow you to make manual adjustments by switching between manual and autofocus modes, but some lenses can be adjusted manually while in autofocus mode without damaging the lens.
You should look at the aperture size of any digital camera lenses you consider purchasing, regardless of whether you want zooming or prime lenses. Prime lenses have a fixed focal point and cannot be used to zoom, but provide stable images and often have fairly large apertures. The aperture size of digital camera lenses is typically indicated by a number such as “f/4” or “f/2.8.” For these numbers, a lower value indicates a larger aperture and more light can be captured by the lens in a short period of time, allowing for faster picture-taking and the ability to take images in low light without a flash.
Different camera manufacturers also tend to use unique mounting systems for their cameras, so you should look for digital camera lenses that can be mounted onto your camera. This usually means you should choose lenses made by the same manufacturer as your camera. There are some third-party companies, however, which make lenses that can be mounted onto multiple camera types.