Posted December 10th, 2008
by Tim Harris
by Tim Harris
The purchase of a new Canon Camera can at times be trying as there are many technical terms which are foreign to a layperson. For a person to be able to make an informed choice, they will need to learn some of the terms that are commonly used. Terms like Pixels, DPI, PPI and white balance all are used to describe some of the qualities of a camera. This guide will seek to explain to you what a pixel is all about and how this term is used for rating a camera quality.
Pixel is the short for the term PIicture-Element. All Canon Digital Camera takes pictures and format them as small squares. A digital image might look seamlessly like a normal photograph but if you magnify it to a close range, it actually comprises of a mosaic of millions of small and different colored squares stitched together. Each pixel is further defined by 3 numbers from the range of 0 to 255 from the red, green and blue color channels. For example, a pixel can be defined by 35 red channel, 70 green channel and 255 blue channel. By using this coding system, there are 16 million possible combinations of color coding. In computer terminology, pixel colors are referred by an 8 bit (bytes) number. Therefore a computer will recognize the color of a pixel by 3 eight bytes numbers, a number for each of the 3 color channel.
Beside from using pixel counts for the display of digital images, nowadays, Digital Camera manufacturers also uses pixel counts to grade the capabilities of their digital cameras. Canon has digital cameras which range from 5 to 10 million pixels. They are normally classified as megapixels cameras because one mega pixels is equivalent to one million pixels. When we say a camera can take 5 megapixels pictures, this mean the digital image which the camera takes have 5 million pixels in it. The numbers of pixel a digital camera has is not important when the image is used displayed on a monitor. However when you need to print these images, the pixels do matter as the higher the picture count, the sharper and crisper the prints will be.
When taking into account pixel counts, it is also important to differentiate between “Total Pixels” or “Effective Pixels”. Total Pixels takes in consideration every pixel in an image. However, normally in the final image, the edge pixels are not used at all. Thus Effective Pixels refers to the numbers of pixels used after the edge pixels of the image are discarded.
Depending on the size of the pictures that you wanted to print, a 5 megapixels Canon camera, makes very good quality 5″ X 7″ printouts and decent 8″ X 10″ printouts. But if you are going to make 8″ X 10″ printouts most of the time, then a 8 megapixels or 10 megapixels Canon camera will be more ideal choice to purchase.
Tags: arts, Cameras, canon, canon camera, digital camera, entertainment, Photography, shopping Posted in Photography
Posted December 9th, 2008
by Tim Harris
by Tim Harris
When Harold Edgerton invented the modern electronic flash in 1931, the world of photography was revolutionized. The principle behind the electronic flash is that when you charged up a capacitor or condenser and release the energy through a flash light bulb (A glass bulb containing inert gases), a split second burst of light will occur. This output of light occurs instantly when you send power to the flash light bulb. Therefore you can control this output of light through regulating the duration of electrical pulses to be sent to the flash light bulb. Before the advert of modern electronics, the duration of electrical pulses used to be controlled by a component called the thvristor. Today, modern electrical circuitry has taken over the function of this component.
On the whole there are two ways to control the amount of light which enter the camera. By adjusting the shutter speed you can determine how long the exposure time is. The other way is to adjust the aperture of the lens. By doing so you will how much light will get to enter the camera. However Flash photography is different from normal photography. This is because of the speed of a burst of the flash light. The time taken for a burst of light takes only micro seconds. This time frame is so short that the speed of a mechanical shutter is no longer a relevant factor in determining the amount of light entering a camera except when the camera is programmed under the FP mode.
The speed of the camera’s shutter is only important when the ambient light is a continuous source. But the duration of a flash pulse is too brief for the camera mechanical shutter to even react to the change of light. Therefore the way to control the quantity of a flash pulse entering the camera is by:
Changing the lens aperture size. The aperture is the physical diaphragm of the camera lens and this control the quantity of light which enters the lens.
Adjust the distance between the subject and flash unit. This method is an application of the laws of physics. The further an object is from a light source, the less illuminated the object is.
You can also regulate the amount of light from a flash unit to a subject by using a diffuser. Of course, you have to consider the trouble of lugging around all these items on location.
By regulating the duration of electrical energy to be sent to the flash unit. By control the energy pulse, you control the duration of the flash burst. This allows you to determine how much light will be emitted to enter the camera. Nowadays, this is the principal way to control the electronic flash output.
In conclusion, this is the main principle of flash metering. The precise measure of flash metering is difficult and it requires years of experience before anyone can accurately judge the right duration for the electrical pulse to be sent to the flash unit. Nowadays, we are fortunate as camera like the Canon EOS digital camera fulfill this function automatically with modern electronics.
Tags: arts, Cameras, canon, canon camera, digital camera, entertainment, Photography, shopping Posted in Cameras
Posted December 6th, 2008
by Tim Harris
by Tim Harris
This guide will seek to provide you with an explanation of the various concepts and terms which are used which respect to Canon EOS flash photography.
Flash and Strobe
The main differences between a strobe and a flash are the use of terminology according to UK or US English. In the US, a strobe is a flash unit whereas in UK a strobe refers to anything emitting blinking lights. Another confusion in terms is the between “Speedlight” and “Speedlite”. Both are trade names of Nikon and Canon respectively used for their series of flash units.
Guide Number
The guide number is the maximum range of a flash unit when it gives out its flash pulse at its maximum setting. However, if you are using automatic flash metering, the number is not relevant. This number only becomes important when you are involved in manual flash settings.
EV (Exposure Value)
EV or Exposure value is the value used for deciding the sensitivity of the AF (Auto Focus) system or exposure metering which respect to film types or lenses. You need to combine the aperture and shutter speed together to get this value. For example, 1/125 and F2 is equal to EV9 which is also equivalent to F4 and 1/30.
Dedicated or Non dedicated flash units
Camera Manufacturers like Canon manufacture their own line of flash units to cater for their own range of cameras. The Canon line of flash units is known as the Speedlite series. These flash units are able to communicate with camera system thus allowing the photographers to enjoy more precision photography. They are called dedicated flash units. Non dedicated flash units are those flash units which are manufactured by third party manufacturers. They are usually generic and are not able to communicate with the camera system.
Shoe Mount
The rectangular slide-in socket which is usually located on top of the mirror or prism housing is known as the shoe mount. This mount is usually used for affixing the external flash unit to the camera. Sometimes it is called a Hot Shoe Mount as it has an electrical trigger to initiate the flash unit once the external flash is fixed to the camera. The Canon EOS Cameras have 4 additional contact points in the shoe mount which helps to transmit flash data from the trigger.
The Redeye Effect
When the light from a flash unit is reflected back into the camera off the walls of the retina, this will produce the Redeye effect which we always see in pictures taken in low ambient light conditions. This due to the fact that the low ambient light condition causes the pupils of the eyes to dilate bigger and the color red is because the retina walls are lined with red blood vessels.
Redeye Reduction
To overcome the problems of Redeye effects, you can increase the distance between the flash and the lens of the camera. Or you can also reflect the flash light off the walls instead of direct illumination on the subject. An alternative way is to get the subject to look at a bright light just before taking their picture. What this does is to cause the pupils of the eyes to dilate smaller resulting in less reflection from the retina.
Tags: arts, Cameras, canon, canon camera, digital camera, entertainment, Photography, shopping Posted in Cameras
Posted December 4th, 2008
by Tim Harris
by Tim Harris
Confusion always results when users of Canon EOS camera tries to use the various modes available without trying to understand how they work. This is because the Canon EOS Camera has different modes like AV (Aperture Priority), TV (Shutter Priority), Program (P) and Manual (M) mode to handle its operations. The differences in they way they handle flash illumination is more obvious especially when the ambient light is low. This guide will give you a brief rundown on the various modes so that you will have a better understanding. We are also assuming that the FP mode of the camera is not turn on.
The P (Program) Mode
Under the P mode, when the ambient light is low, the camera will be set to a high shutter speed to enable you to use the camera without a tripod stand. This is to enable you to avoid “motion blur” even though you are holding the camera with your hand. The P mode will work when the ambient light is low or high. When the ambient light is high, the camera makes the assumption that you will flash fill the foreground. Thus the flash will be low powered. If the ambient light is low, the camera will under the P mode will set the flash and the shutter speed appropriately to give the best possible result. Having said so, pictures taken under this condition will normally have a dark background.
The TV (Shutter Priority) Mode
With this mode, the Camera lets you decide the shutter speed instead. It will decide on the aperture priority settings to suit the shutter speed that you have chosen to make sure that the exposure level is correct. The flash pulse duration will be decided by the flash metering system. In essence the Camera will always function under fill flash mode when in TV mode. This is the opposite of the “P” mode. The Canon EOS system will also indicate to you if the background is too dark. You will see this warning when the Maximum aperture settings begin to blink in the viewfinder. If this happens, you have to reduce the shutter speed and use a tripod stand to hold the camera to avoid motion blurring.
AV (Aperture Priority) Mode
With this mode, you can fix the depth of field (DOF) by adjusting the lens aperture. The camera will determine the correct shutter speed for exposing the background to the correct level. The metering system will decide also how long the flash pulse should be. You have to note that if the shutter speed is low, you will need a tripod stand to prop up the camera instead of using your hands to hold the camera. This is because at low shutter speed, your pictures will end up having motion blur. Just like the TV mode, the camera operates fill flash mode. There are several cameras which have the exception to this mode. The canon EOS10/10s and the Canon Elan II/ EOS 50 models has a unique function will lets you lock the X-Sync speed to the Shutter Speed.
M (Manual ) Mode
Under this mode, you will specify both the shutter and aperture speed of the camera. You will also determine the exposure setting of the camera. The camera will, through the flash metering system, calculate the flash output to illuminate the fore-ground.
Tags: arts, Cameras, canon, canon camera, digital camera, entertainment, Photography, shopping Posted in Photography
Posted November 14th, 2008
by Tim Harris
by Tim Harris
Taking Pictures with Flash Photography is a very easy thing to do but to master it as a technique is an entirely different matter. Comparing to an automatic flash, to get a natural looking picture with electronic flash will require a skill which needs to be mastered. The reason is because our eyes cannot discern the effects of the flash as the burst time of the flash is too short for us to process. In addition, we can’t even view the flash as we look through the viewfinder of the camera. In this guide, we will give you 5 tips to help you achieve better looking pictures using the right type of techniques.
Using the Canon Digital Camera Internal flash as opposed to the External flash.
Generally when we take pictures in settings like a restaurant or party situation, the use of an internal flash is more than adequate because the subjects to be photograph is usually at a close distance. The power of the internal flash unit will be powerful enough to illuminate the scene. Although the light from an internal flash is harsh, the conveniences of not lugging around an external far outweigh its drawback. Nevertheless, if the situation calls for a more professional photographic quality, you will need to use an external flash to do the job. By using an external flash, you will be able to soften the light of the flash unit by reflecting the light off the wall.
Compatibility of Old flash Units with the New Canon EOS digital camera.
Depending on the type of flash that you have, Canon Digital Camera only uses the Canon Speed-lite Flash with those models ending with “EX”. Other models like the “E” or “EZ” models will not be able to work with the Canon EOS Digital camera. Those from other manufacturer require that they support E-TTL flash metering in order for the flash to be compatible with the Canon EOS digital camera.
Unappealing pictures taken under harsh lighting.
Because soft light comes from a big area, internal flash are unable to duplicate such lighting as the light source is from a small area mounted near the lens of the camera. This tends to produce the unappealing result which we always find with pictures taken with internal flash. One way to go around this is to bounce the flash light of the wall onto the subject matter thus softening the light and producing a more natural look. Alternatively, you can also use diffuser to diffuse the light of the flash.
Red eye effect of Flash photography
The most common problem when using internal flash to take a picture is the problem of “Red Eyes”. This happens because the red blood vessels lining the retina of the eyes reflect back the flash light back into the camera resulting in the subject eyes glowing red in the photos. Taking pictures of animal also produces a related problem but this call the “Green eye” effect because of the color pigment of the animal’s eyes. When you use an external flash, you will be able to avoid all these problems.
How to take photos in rapid succession using the flash.
All flash requires a period of time to charge up. If you are inclined to take pictures in rapid succession using the flash, ensure that the flash have “Rapid Fire” ability. This means that, the Flash unit is able to fire off even though it has not reached it full charge capacity. Note that different batteries charge the flash at a different rate.
Tags: arts, Cameras, canon, canon camera, digital camera, entertainment, hobby, Photography, shopping Posted in Cameras
