Taking Photographs

The relationship between and in taking correctly exposed photos

Understanding relationship between SHUTTER SPEED & APERTURE SHUTTER SPEED & APERTURE

Range of listed on the left and shutter speeds on the right CORRECT MACRO / HIGH SHOTS

This is where the balance comes in – for each unique photo opportunity there is an exact amount of light required for proper exposure. In this example, a higher F stop number lets in very little light, so the shutter must remain open longer to allow in the correct amount of light for a good exposure. (BUT THESE ARE NOT THE ONLT SETTINGS THAT WILL GIVE A CORRECT EXPOSURE) CORRECT EXPOSURE SPORTS / SHALLOW DEPTH OF FIELD SHOTS

Shooting exactly the same scene as before, we can set the shutters speed to its highest setting. This allows very little time for the light to enter the camera. In order to get a proper exposure, the aperture must be much larger than before to allow in the additional light needed. For a given exposure, shutter speed and aperture have to be in balance and work together like a teeter-totter (balance bar and fulcrum) Using APERTURE PRIORITY mode

Most cameras allow you to select some degree of automation – one of these modes is APERTURE PRIORITY. With this mode YOU set the aperture and the camera will automatically select a shutter speed to give the correct exposure. The camera still uses this balance principal to do this. Using SHUTTER PRIORITY mode

With SHUTTER PRIORITY mode YOU set the shutter speed and the camera will automatically select an aperture to give the correct exposure. SHUTTER SPEED

The shutter opens and closes to permit light to enter the camera. Obviously the longer the shutter is open the more light is permitted to enter. The classic shutter speeds are 1 second, ½ second, ¼ second, 1/8 second, 1/15 second, 1/30 second, 1/60 second and 1/125 second. Modern cameras offer even more shutter speeds with speeds up to 1/4000 second!

If your camera has exposure compensation control, it helps to you take a picture exposed the way you want it. When the camera has picked the setting it wants but you see the photo is likely to be overexposed, you can use the Exposure Compensation control to correct this. Change the EV to a minus number to make the picture darker, and to a plus number to make it lighter. DEPTH of FIELD

The Depth of Field (DoF) is controlled by the Aperture setting. The smaller the number the less DoF you will have. The larger the aperture number the greater the DoF. This example shows a very high aperture number, (small amount of light coming into the camera) which results in a greater DoF. DEPTH of FIELD

In general when you are taking portraits you want a small amount of DoF (low F stop number). You want the subject to be in good focus and the background to be blurred. When you are taking landscape photos you want a larger amount of DoF (large F stop no.) – APERTURE PRIORITY MODE should be your first choice of setting. ISO (film speed) SETTINGS

With film cameras, the decision is which film to use. Films are rated in ISO numbers, where ISO 100 is for bright outdoors, ISO 400 is for indoor and outdoor use, and ISO 800 and 16000 are for low light conditions. Some digital cameras allow you to adjust the ISO values but in this case you are adjusting the sensitivity of the CCD (charge coupled device) to the light. The higher the setting the more sensitive the CCD is to the light. Problems with high ISO settings

The problem with high ISO films and higher ISO settings with digital cameras is an increase in grain or NOISE. Typically therefore you need to use the lowest ISO setting possible to get a good exposure. There are occasions when it is useful to use higher ISO’s – in low light situations when shutter speeds are so slow that camera shake will ruin your image; where you wish to use a small aperture to get some additional depth of field; for artistic purposes. ISO settings

Here we are using a low ISO value. The balance (teeter-totter) relationship still holds. The only difference is that the CCD needs more light to get the correct exposure so the shutter is open for longer. Good news is that low ISO values give less noise VIGNETTING

Vignetting is when a filter, lens or editing software makes a dark border in the corners of the image. This is bad when you are using filers or an add-on lens. It can be cropped out to improve the image.

In the example here the camera has a 49mm thread on the lens and a UV filter and a polarising filter have been attached. This has led to vignetting on the image.

It can be corrected by adding a 49mm to 55 mm setup ring and then using 55m filters. This takes the edges of the filters outside the image areas and avoids the need to crop the photo DIGITAL PHOTOS – JPEG v RAW

When you take a digital picture the data will go through a lot of different steps before being written to the memory card. The same thing happens to every picture. This processing may be correct for most images but it will not be right for them all, and it reduces the amount of information written to the card – this lost information cannot be retrieved. DIGITAL PHOTOS – JPEG v RAW

In RAW mode the camera takes the data straight from the CCD and writes it to the memory card. It add information about the settings of the camera, but it does not change the image data. With editing software you now have far more control and can get the maximum from your image. RAW images are larger than JPEGs as they are not compressed.