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Monthly Archives: July 2017

Characteristics of Zoom Lens

Image Stabilization (IS) or Vibration Reduction (VR)
Characteristics: Most types of lenses above come in two flavours: either with image stabilization, or without. Built-in stabilization allows you to get sharp hand-held images when lighting conditions are poor, or you’re shooting from a moving vehicle. On the lenses that offer this capability, there is usually a switch that lets you turn the feature off, thus saving batteries when using a tripod. Beware the cost of these lenses, though: you can expect to pay 2-4 times as much for a lens with image stabilization than the same lens without.

Internal Focusing (IF)
Characteristics: The movement of the lens for focusing purposes is internal to the lens body, so no lens ring will cause the lens to twist out and interfere with the orientation of any filters. (Some filters, such as linear polarizers or graduated neutral-density filters require stationary positioning in order to deliver predictable results.) This internal movement also allows the lens weight to stay balanced, which helps the balancing of heavier lenses on a tripod. Image quality of newer IF lenses is slightly better than non-IF lenses due to technological advances made that correct some aberrations.

Constant vs Variable Aperture
Characteristics: Variable aperture accounts for the majority of zoom lenses, and causes the maximum aperture to decrease as you zoom from wider focal lengths to telephoto focal lengths. The advantage of variable aperture zoom lenses is that they’re cheaper to maufacture and are typically lighter and more compact than contact aperture lenses.

Constant aperture lenses provide a static maximum aperture regardless of the focal length you’re zoomed to. This better enables you to achieve narrow depth of field so as to isolate your subject from your background. These lenses typically let more light in, which lets you shoot sharp photos in dimmer lighting conditions.

Macro Focusing
Characteristics: Macro lenses allow the camera to be very close to its subject and still focus sharply. Macro lenses are ideal for close-up shots of flowers, leaves or insects, and sometimes double as portrait lenses. They typically have a reproduction ratio of 1:4 or better, which means the image sensor will capture the subject at 1/4 its original size or larger.

Low-Dispersion Glass
Characteristics: Some lenses are made with high-quality glass specially manufactured to more accurately transmit the full visible colour spectrum, called low-dispersion glass. You may also hear of ED (extra-low dispersion), SLD (super-low dispersion) or UD (ultra-low dispersion), which really just means truer colours.

Apochromatic Lenses (APO)
Characteristics: Apochromatic lenses have high colour fidelity and sharpness and should be used by anyone obsessed with getting to the most accurate colours possible.

Aspherical Elements (ASP)
Characteristics: Aspherical lenses are made with a different curvature than traditional spherical lenses to correct for distortions at the edge of the image. They are particularly useful in wide-angle lenses where vignetting or distortion can be seen in the corners of the image.

Tripod Mounts for Long Lenses
Characteristics: Lenses that are bigger and heavier than your camera body should have a tripod mount built-in. By attaching the lens to the tripod instead of the camera, you will remove tension on the camera-to-lens mount joint, and you will improve tripod balancing in the field. In fact, without a tripod mount, some larger lenses will cause the tripod to topple, thus making tripod use impossible without a lens mount. It is possible to purchase a separate adapter bracket from some manufacturers if the lens itself does not have one.

Plastic Material vs Alloys
Characteristics: Plastic lenses built recently typically use high-tech materials that are very durable and much lighter than metal alloy lenses. So although it used to be said that plastic lenses are cheap and unreliable, that is no longer true today.

Size
Characteristics: Zoom and telephoto lenses are getting smaller and lighter each year. In general, the larger the focal length of the lens, the larger the lens will be physically.

Weight
Characteristics: The heaviness of a lens may be prohibitive to you, depending on your physical fitness level and how long you’ll be away from home. Plastic lenses are quite durable and are definitely lighter than equivalent metal lenses, although ultra-lightweight metal alloys are reasonable as well.

Price
Characteristics: In general, no matter which lens you’re looking at, prices vary dramatically based on lens quality. Professional lenses will cost you thousands of dollars, while a compact modest starter zoom lens will be only a hundred dollars. You’ll pay extra for some of the characteristics discussed in this article, such as fast constant apertures, high quality glass, image stabilization, and quick auto-focus. Remember, though, that lens price is a large investment: lenses will long outlast your camera body, and is largely responsible for the quality of your images (much more so than the camera body itself)!

 

Underwater Photography

If you simply want an underwater camera for a day, you might want to consider either a Kodak or a Fuji single-use disposable camera. For those beginning in the field of underwater photography, an inexpensive waterproof disposable camera can be a good way to get started. Some of the disposable underwater cameras are equipped with an integrated flash unit.

One of the difficulties casual snorkelers and divers who are attempting underwater photography struggle with is the lack of visibility in the view finder on underwater cameras. Too many commercially built underwater cameras cases merely depend on lining up dots, which isn’t sufficient for proper composition of underwater pictures. Very few underwater cameras have a finder large enough to be used accurately underwater.

Serious enthusiasts who want the advantages of a single-lens reflex auto-focus camera may prefer a land camera in an underwater housing. Some of the more advanced and specialized cameras have an underwater mode that change the features, operation, or interface of the camera for underwater use. Imagine having an underwater camera that takes 220 shots at 12 million pixels that you can see and delete underwater. When most people think about shooting digital pictures underwater, they think of large underwater camera housings, intricate flash strobes and a very large budget. But that is not always the case Canon is making an entire line of underwater housings for many of its digital point-and-shoot cameras in the PowerShot line. While serious underwater photography still requires higher-end equipment, these cameras and housings can produce some very good results. Digital cameras can also afford more shooting time underwater with a larger 1-gig compact flash card.

Another important item to consider before taking any underwater shots is the proper camera lens. The basic camera systems available for underwater photography have a thirty-five millimeter lens.

There are some real disadvantages to underwater photography. One particular challenge in underwater photography is the use of a flash. Flash photography underwater is limited in range to about 8 ft at the extreme, 4-6 ft commonly.

Browse through any collection of (good) underwater photography, and you will see that every image is either macro or wide-angle, without exception. For this reason alone, many divers new to underwater photography start by concentrating on macro subjects. Doing macro underwater shares many of the same concepts as shooting on dry land. The trick is to shoot close with a wide angle with an auto-focus camera because depth of field underwater is very unforgiving. If you’re a new to underwater photography, four feet should be the maximum distance from which to photograph your subject. When you are estimating the camera-to-subject distance underwater you are estimating the apparent distance, the actual distance is 25 percent further away.

Remember Underwater Photography starts as skill development, then composition followed by technique and finely artistic realization. Many of the rules of land photography still apply underwater but they must be used with some thought. The irony of underwater photography is that for all its beauty, the biggest enemy is the water itself. Unlike taking photos topside, when reloading is a simple process, cameras cannot be reloaded underwater.

Even if you are not using it for underwater use, sand and sea air can damage the delicate mechanisms within the camera. To take effective pictures underwater you need to be able to concentrate on your subject and the operation of your camera equipment. Underwater photography is great fun, but getting good results is extremely tricky and the equipment is very expensive.

 

Pick Camera With The Proper Number Of Mega Pixels

As with many other things when it comes to mega pixels more is not necessarily better. There are many considerations when buying a camera and the number of mega pixels is just one of them.
One of the most important things to consider is usage. More mega pixels are good for people who plan to print photos (especially enlargements) or for people who need to zoom in and grab fine details from a big photo. If the main usage of the photos is watching them on your computer screen and maybe printing a few 4X6 prints than 2 mega pixels is more than enough (yes… just 2). Most screen resolutions are 1024X768 so even when viewing the photo in full screen mode you can only view 1024X768 < 1 mega pixels. A 2 mega pixels 4X6 photo print will have a DPI higher than 300 which is more than enough for a good quality print.

If you plan to use your photos for enlargements than a rule of thumb is to be able to print at least 300DPI resolution. The following is a table for different print sizes and the needed mega pixels for such print quality:

page 4X6 2MP
page 5X7 3MP
page 8X10 7MP
page 11X14 14MP
page 16X20 28MP
page 20X30 54MP

Another practical consideration is price and budget: Usually the more mega pixels the more expensive the camera is. Unless your budget is infinite when buying a camera you make a compromise between mega pixels and other features. For example is it better to spend money on more mega pixels or on better lenses? Or maybe instead of getting the latest number of mega pixels get an external flash for low light photography? When buying a camera try to predict what and how you will use it. In many cases a lower mega pixels sensor with better a lens will result in a much better photo than a high mega pixels with an inferior lens. Shop around and make sure that you get the best package in terms of mega pixels and other features.

To conclude when shopping for a camera it is best not to be a victim of the mega pixels race. Although it is generally a good thing to have a high number of pixels there are many other factors that influence the quality of the photos taken and the choice of the right camera for you. Lenses, battery life, light sensitivity, sensor technology used, external flash and many other features are not less important as the number of mega pixels. When shopping for a camera make sure that you consider the whole package and not use the number of mega pixels as a “quality” indicator for your buy.