I am sure you have seen portraits where the background is nice and blurry, to achieve this effect you need to you a wide aperture, and this means a small f/ number, say 2.8 or 5.6.
To master depth of field you need to understand aperture. So place you camera in A or Av priority mode, this way the camera chooses the shutter speed and you choose the aperture.
When you want the complete photo in focus then choose a large number, this mean a small aperture. The aperture should be f/11 or higher.
Below is a chart to illustrate the aperture, on the left of the chart you have a wide aperture, this means: less in focus, blurry background, shallow depth of field, a small number. Uses: portraits, fine arts, when you want to highlight a part of the photo and leave the rest out of focus.
On the right of the chart is small aperture, this means: more in focus, sharper background, deep depth of field, a larger number. Uses: landscapes, and to keep the majority or all of the photo in sharp focus.
When using a wide aperture you will let plenty of light in, and the shutter speed will be fast (depends on the amount of light though) when using a small aperture then the shutter speed will be slower, to compensate a tripod or a faster ISO can be used.
Shutter speed. Place the camera in S or Tv priority mode, this way the camera will choose the aperture for you.
Used for freezing the action, creating blurred effects in water, nighttime photography, but there are more uses of course.
If you want to photograph a child or dog that is moving fast you´ll need a fast shutter speed or your subject will be blurry. You can also use a higher ISO as this will help you use a faster shutter speed, the downside with high ISO is noise, of course this is getting better with the newer camera models.
If you want to make the water from a waterfall blurry, you will need to choose a slower shutter speed and probably use a tripod to help keep the camera steady.
When you use shutter priority then the camera will choose the aperture and if the light is low it will use a wide aperture, this might or might not be what you require so remember these limitations.
Above is a chart with the shutter speeds. On the left is a slower shutter speed, here a tripod will be required to keep the camera still, the longer the shutter speed, the more light is let in to the sensor. On the right of the chart is fast shutter speeds, these speeds are perfect for action photography, the exposure is short and therefore less light is let in to the sensor, the shots will be sharp as there is less chance of camera shake but the aperture will be set to a wider aperture to compensate for less light.
ISO is the number used to express the light sensitivity of the digital camera. Remember the olden days when there was a number on the film 100, 200, 400 film speed? Well it is the same thing only you get more flexibility as you can change the ISO with each photo, awesome really, well, there are downsides. ISO = noise (better cameras and newer models are getting around this now) and noise isn´t always what we want to there is that to take into account. A higher ISO means you can use a faster shutter speed, great for those times when there is little light. If you are using a tripod for night photography then it is recommended to use a low ISO to eliminate the noise.
Now put these three: aperture, shutter speed and ISO together and you have the exposure triangle. If you put the camera on Manual Mode (M) then you control the exposure completely.
There is a downloadable pdf with information charts on manual photography. To download please use this link. www.fotografiadelecuador.com/tutorials/manual_photography_cheat_sheet.pdf
You can also view this information on Exposure Triangle Here
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