Monday, December 3, 2007

Photographic filters

Photographic filters have been in use for a long time. They were required for special effects or to enhance the contrast of some colors. They were also used for white balance.
For example, a film set for daylight color temperature, would have produced yellowish photos when taken inside, with incandescent light bulbs lighting the scene. To compensate, a blue filter had to be used, to get the right colors.
The major advantage of digital cameras is the fact that you can adjust the white balance of a scene electronically, without the use of a color filter. As far as the image effects that could be obtained with some filters (like blurring the image, changing color hue for specific areas of a photograph, etc.) there are better ways of getting them onto a photo.
Very cheap image software can produce more effects on a photograph than all the filters in the world combined. With a little bit of imagination, using software to get the effects you want is the best way to go.
The only filter a digital camera actually needs is a polarizer.
Polarizers come in two varieties:Linear polarizers Circular polarizers
Each has the same effect but circular polarizers are more expensive. Digital cameras can use both (linear and circular) polarizers.
Polarizers produce deeper colored blue skies, minimize light reflections from glass and water and reduces glare from non-metallic surfaces. They also provide good color saturation. Can be used in extremely bright light situations to reduce the amount of light entering the camera; this enables more selective depth of field control.

Exposure Compensation

Exposure Compensation is a feature on a digital camera that allows you to adjust the shutter speed measured by its light meter. Usually, the range of adjustment goes from +2 to -2 EV in 1/3 steps.
Lets say that you point the camera at you subject and the meter says you need 1/250 sec. shutter speed at aperture 5.
If for whatever reason you select +1 exposure compensation, the shutter speed used by the camera will be 1/125 sec.
If you use -1 exposure compensation, the shutter speed will be 1/500 sec.
Every increment in exposure compensation (+2 +1 -1 -2) increases or decreases the amount of light going through the camera by a factor of 2.

White Balance

The white balance setting for a digital camera is very useful in dealing with various light conditions. The best way to understand this setting is to place a white sheet of paper in front of your camera and take a photograph.
If the image has a white sheet of paper in it, you're ok; but if the paper has a yellowish hue, you're in trouble.
To better understand this process, take a look at your lamp. It usually uses an incandescent bulb. If you look closely, you'll notice that the color of this particular source of light has a yellow hue. The digital camera amplifies this hue and you get a yellowish photograph.
So, before taking any photo, look around at your sources of light। Even if you are outdoors, there are white balance settings that will make your photo look a lot better.

Daylight white balance
Cloudy white balance
Tungsten white balance
Fluorescent white balance
Flash white balance

Focal Length

The focal length of a digital camera lens is the distance between the center of the lens and the image sensor when an in-focus image is formed. The focal length of a digital camera lens is displayed on the barrel of the lens along with the measurement of the largest aperture and the maker.
The focal length of a lens establishes the field of view of the camera. The shorter the focal length is, the larger the field of view.
Camera lenses are categorized into normal, telephoto, and wide angle, according to focal length. Thus a 200 mm equivalent telephoto lens gives a 4 x magnification over the 50 mm equivalent lens.

Image Format

Digital cameras store the images they produce in two different formats: JPEG and RAW. JPEG is the most common used image format, while RAW is usually used by professionals.
The differences between the two go beyond the image size. A JPEG image is a compressed image, for example, an 8 MB RAW image can be compressed to a 3 MB full quality JPEG.
The RAW format produces much more that a BIG image. It also has been described as a "digital negative". Professional photographers use RAW because they can make later modification to the image that wouldn't be possible using JPEG.
The disadvantage is the fact that you need specialized expensive software to read and modify RAW format images. You also need time and patience. Let's say that you make 100 photos in RAW format and 100 photos in JPEG.
The JPEG images are ready to use, you may discard 20 of them because of bad exposure, but you have the rest of the images ready to be printed or to be published on the Internet.
With RAW images, you'll need at least 1-2 hours of opening the 100 images with photo editing software and tweak their properties to the point when you'll get the image you want.

Image Stabilization

Image Stabilization is also known as vibration reduction and anti-shake; it is a technology found on digital cameras with long telephoto zooms (10X and 12X). It helps prevent images from becoming blurred.
This technology helps people in taking photos that require slow shutter speeds. The system works in two different modes. There are systems that stabilize the shot by moving the image sensor or by moving optical elements inside the lens.
This anti-shake system can make the use of a tripod redundant, but there are situations when at very slow shutter speeds (>1 sec.) the image stabilization cannot cope with the movement of a hand held camera.

Image resolution

Is the most talked about feature of a digital camera. From 3 to 12 megapixels or more, it seems that with every generation of digital camera there is an increase in image resolution.
But what is a megapixel? Well, a megapixel is represented by 1000000 pixels.
So, if the maximum resolution of a digital camera, results in an image 3000 pixels in width and 2300 pixels in height, that camera would be a 3000 x 2300 = 6900000 / 1000000 = 6.9 MEGAPIXELS
When talking about megaspixels, there is the question: how much do you need? Especially because the more a camera is capable, the more expensive it is.
If you are going to use the images on the Internet, you may find that the maximum resolution of 1600 x 1200 might be enough. That would lead you to buy a 1.92 Mpx camera!
If you want to print an image, you need to consider the dpi requirements. 300 dots per inch is a standard in printing any image. It simply means that all you have to do to find out the maximum width of a printed image is to divide its width in pixels by 300.
3000 pixels / 300 = 10 inches maximum.
However, the more megapixels a camera has, the better the optics on that camera, and so you get far better images.

ISO Speed


ISO speed shows how sensitive the image sensor is to the amount of light present. The higher the ISO, the more sensitive is the image sensor.
The ISO is represented by numbers:
ISO 50 100 200 400 800 1600 3200


Each number represents two times the sensitivity than the previous one। Higher ISO settings are very useful in low light situations, but the disadvantage of noise appears. The higher the ISO, the higher the noise levels you get.


Shutter Speed

The shutter is a mechanism that controls the exposure time of an image. This time can be manually set by using the shutter priority shooting mode from your digital camera. The numbers you'll use will look probably like this: 15, 13, 10, 8, 6, 5, 4, 3.2, 2.5, 2, 1.6, 1.3, 1, 0.8, 0.6, 0.5, 0.4, 0.3, 1/4, 1/5, 1/6, 1/8, 1/10, 1/13, 1/15, 1/20, 1/25, 1/30, 1/40, 1/50, 1/60, 1/80, 1/100, 1/125, 1/160, 1/200, 1/250, 1/320, 1/400, 1/500, 1/640, 1/800, 1/1000, 1/1250, 1/1600, 1/2000 sec.
These numbers represent how long the light will be allowed to hit the digital sensor in order to capture the image

Aperture


Aperture is a device that controls the quantity of light that passes through the lens। It is an iris type mechanism, which shrinks or grows in order to let in less or more light.

Each number lets in two times less light than the previous one.
Small numbers represent a large aperture, big numbers - small aperture. Most digital cameras do not have this numbers written on their lenses, but they use aperture as part of their construction. It is also the way for you to select aperture priority shooting mode from your camera to control the depth of field.

Tuesday, November 27, 2007

Things To Consider Before Shooting Pictures

Before you are able to take the kind of pictures you want to learn to take, it is important to think about the equipment you would like to start out with. Probably the most important decision you will have to make is what kind of camera to buy. There are so many options and companies now that the whole process can seem quite overwhelming

If you are planning to become a serious photographer you should probably buy an SLR (Single Lens Reflex) camera. The term single lens reflex comes from the fact that the camera has a view of the subject through a single lens and that view is reflected to the viewfinder so the photographer can see exactly what is going to be in the picture. The Digital SLR's are getting so advanced that it's very hard to chose a film camera over a digital. The main advantages of an SLR camera over a point-and-shoot digital camera is the fact that you can change lenses and filters whenever you want to. Although new point-and-shoot cameras have increasing optical zoom and similar capabilities. Point-and-shoot cameras are also a great idea if you just want something simple and small that is convenient to carry wherever you go.

Lenses are what your camera uses to focus on the world. All lenses are defined by their focal length and aperture. The focal length tells you what the angle of view is and how far it magnifies. The aperture is the amount of light that the camera is letting into the sensor. Any lens lower than 50 mm focal length is considered wide-angle. Any at 50 mm is considered normal. And any lens above 50 mm is considered a telephoto. But there are also zoom lenses that have a variable focal length. With a zoom lens you can cover a wide range such as 28 mm to 105 mm or 80 mm to 210 mm.

Lenses can be very expensive and very cheap and it is usually the faster lenses or the ones with the wider apertures that are the highest priced. The faster lenses are more appealing primarily because they can produce better pictures in dim light without a tripod. But it is quite possible to find great lenses at low prices. Probably the first lens you buy should be broad range zoom lens such as a 28 mm to 105 mm. The slight drawback of zoom lenses is that they are slower and they don't quite match the sharpness and contrast of a fixed focal length lens.

Another very important item that you should definitely acquire is a ultra-violet filter (UV filter). It is a simple piece of glass that screws on to the end of your lens and protects it from scratches, dust, dirt, moisture and fingerprints while reducing unwanted ultra-violet light.

We would also strongly recommend that you buy a tripod of some kind which is vital when there is not enough light to handhold a picture. Some of the best pictures you've seen at dusk, night, or just when its cloudy have almost certainly been taken using a tripod. Tripods allow you to use your camera's full range of shutter speed and aperture combinations which can sometimes creating amazing unexpected results. You should pick a tripod that is plenty sturdy but also convenient enough to carry wherever you might want it. You also might want it tall enough so you can look through your camera at eye level.

But when you buy a UV filter you might as well get a polarizer filter as well.A polarizer filter is most commonly used for darkening the sky by cutting through atmospheric haze. This affect can also dramatically improve the results of black and white photography. Polarizer filters are also good for removing reflections from glass or water.

Memory cards are extremely convenient with digital cameras but you need to make sure you have all the space on them that you want. It is always a good feeling to know that you can take all the pictures that you want when you think you have a good opportunity. Most SLR's take Compact Flash memory cards, smaller cameras usually either take Secure Digital memory cards or Sony memory sticks.

It is convenient to have only one format of memory card if you have multiple cameras because then you can interchange them even between a big SLR and a small point and shoot camera. The smaller cameras usually use secure digital cards and Sony memory sticks but some very nice ones use compact flash cards. One thing you must always do is remember to format the card after you unload pictures and put it back into the camera or else you won't have the full capacity of the card.

Nikon D3 Hands-on Preview


The professional Nikon D 'single digit' series of digital SLR's started life back in June 1999 with the groundbreaking D1. Groundbreaking because it was the digital SLR which broke Kodak's stranglehold on the digital SLR market and fundamentally brought prices down to a level which most professionals could afford (around the US$5,500 mark). Since then we have seen a steady progression of this line of cameras, while the core values of a high quality full size body with integrated grip have remained the line split into two halves, one targeted at high resolution photography the other high speed sports type photography (lower resolution but faster continuous shooting); the X and H suffixes. It's been almost three years since Nikon introduced a completely new digital SLR with a new sensor (the D2X) and there has been much anticipation that Nikon's next move would be a full-frame chip.
This predictions have come true with the introduction of the 'FX format' (new moniker created by Nikon) D3 which features a 36 x 23.9 mm 12.1 megapixel CMOS sensor as well as a vast array of new features which absolutely raise it another notch above previous single digit Nikon DSLRs. Important headline improvements include high sensitivity support by default, up to ISO 6400 with 25600 available as a boost option, 14-bit A/D conversion, a new standard image processor, a new shutter, new auto focus sensor, focus tracking by color, nine frames per second continuous, dual compact flash support, DX lens support (albeit at lower resolution) and a 3.0" 922,000 pixel LCD monitor (which it has to be said is lovely).
Some will undoubtedly question Nikon for 'only' delivering twelve megapixels on their first full frame digital SLR, all we can presume by looking at past model line history is that this camera is designed for speed (both in sensitivity, auto-focus and continuous shooting)।


Nikon D3 Key Features
-First ever Nikon DSLR with a Full-Frame (36 x 24 mm) sensor (coined FX format)
-12.1 megapixel full-frame sensor (8.45┬Ám pixel pitch)
-ISO 200 - 6400 (with boost up to ISO 25600)
-Also supports DX lenses, viewfinder automatically masks (5.1 megapixels with DX lens)
-5:4 ratio crop mode (10 megapixels, up to 9 fps, viewfinder masked)
-14-bit A/D conversion, 12 channel readout
-Nikon EXPEED image processor (Capture NX processing and NR algorithms, lower power)
-Super fast operation (power-up 12 ms, shutter lag 41 ms, black-out 74 ms)
-New Kevlar / carbon fibre composite shutter with 300,000 exposure durability
-New Multi-CAM3500FX Auto Focus sensor (51-point, 15 cross-type, more vertical coverage)
-Auto-focus tracking by color (using information from 1005-pixel AE sensor)
-Auto-focus calibration (fine-tuning) now available (fixed body or up to 20 separate lens settings)
-Scene Recognition System (uses AE sensor, AF sensor)
-Picture Control image parameter presets (replace Color Modes I, II and III)
-Custom image parameters now support brightness as well as contrast
-frames per second continuous with auto-focus tracking
-Eleven frames per second continuous without auto-focus tracking
-Ten / eleven frames per second continuous in DX-crop mode (AF / no-AF)
-Dual Compact Flash card slots (overflow, back-up, RAW on 1 / JPEG on 2, copy)
-Compact Flash UDMA support
-3.0" 922,000 pixel LCD monitor
-Live View with either phase detect (mirror up/down) or contrast detect Auto Focus
-Virtual horizon indicates if camera is level (like an aircraft cockpit display)
-HDMI HD video output
-'Active D-Lighting' (adjusts metering as well as applying D-Lighting curve)
-Detailed 'Control Panel' type display on LCD monitor, changes color in darkness
-Buttons sealed against moisture
-Dual battery charger as standard
-Available November 2007

Nikon D3 and d300 now support 'D2X mode'




Nikon, obviously realizing that many users of its previous flagship DSLR will be migrating to its successors, has made available 'Picture Controls' aiming to emulate the color reproduction of the D2X(s) on the new D3 and D300। There are three such controls, mirroring the original color modes I to III। These settings may be used as a base point to add further tweaks and should prove a major time-saver to photographers wishing to upgrade their camera bodies and continue with their existing workflow। The Picture Controls are available now via Nikon's website, links after the jump.