Can someone rewrite this in their own words please. Open Depth of field is controlled by changing the aperture setting on your camera. Like your eye, a camera lens has an iris inside that can open or close to let in more or less light.
A shallow depth of field is the small or narrow area in an image that is in focus. Often, the background is blurred while only the subject stays in focus.

The open depth of field can be compared to an eye. Your eye contains an iris that either expands or contracts when exposed to certain amounts of light. It can be referred to as the aperture settings on your camera. A shallow depth of field is when a focus point of your picture is very clear, while other parts, such as the background, are blurred.

one is a red flower, and one is the sky when the sun sets.

the present continuous is a verb tense which is mainly used to indicates that an action is in progress at the moment of speaking.  

it is formed using: person + verb to be (am/is/are) +verb + - ing form  

example: i am studying at this moment .

in addition, the present continuous is also used in order to express things that will or will not happen in the near future.

example: i am having dinner with some friends tonight.

the speaker sometimes   uses it   to express that an action is repeated and it causes irritation on the part of the speaker

example: my sister is constantly complaining about everything.