Controlling and creatively using depth of field in video composition is the mark of a true professional...! Let's take a look at some of the ways you can use this…!
Okay… Let's define depth of field…
* Depth of field is the range of distance that appears acceptably sharp when you are looking through the viewfinder or at the LCD screen.
That is an important point!
What do you want your audience to see?
As in all video composition , depth of field is really quite subjective!
The "acceptable" depth of field will differ from one person to another based on what you want visible in the frame.
In video composition depth of field in any shot or scene will be determined by where you want your audience's attention to go and/or what type of emotional environment you're trying to create.
The depth of field in any shot or scene can be varied in several different ways.
If we further define depth of field as...
We can then start to get some ideas on how we can vary the depth of field in the shot so that it can be used creatively in our video composition. But... How do we actually control the depth of field so we can use it creatively?
Okay... let's take a closer look at three of the main ways to control depth of field...
What is an easy way in video composition to control the depth of field?
Well… On the higher-end professional cameras we could first work a bit with adjusting the aperture setting of the camera. This is done by changing the diaphragm opening (f–stops) of the lens.
Here are some examples of how you might go about doing this:
If it is a given (a fact)... that we have the subject at the same distance and the same image size... Then the larger the lens opening (the more light you let in) the smaller the area of depth of field.
In other words… The area to the front and the back of the subject will tend to be out of focus. Of course ... one of the drawbacks may be that the zone of sharpness will be more
limited but... It can be a plus however that you'll be able to shoot in lower light.
Now... If you go to a smaller aperture setting (allowing less light in) you will have a deeper (more area in focus) depth of field. But, of course will you have enough light to shoot at that f-stop (aperture) setting? If you work with this a bit and understand it you should be able to use it very easily when you're composing and shooting a scene.
Knowing your camcorder Lux ratings and the camcorder light sensitivity will help you when you're making your decisions about using the aperture setting to control the video composition depth of field.
Another way to control depth of field is to vary the distance between you and the subject you're shooting.
And of course the opposite is true...
This is a simple but very effective way to control the depth of field in your shot as you can quickly see in your viewfinder or LCD screen the depth of focus as you move in and out from the subject.
Now… If you really want to shoot your video like a Pro…
Controlling your depth of field this way can be precisely planned out as part of the script and then storyboarded out as far as types of
shots and camera angles and the effects you want to create with each one of them. You can have a lot of fun with it!
To use this aspect of controlling the depth of field you would of course have to have a camera that can use interchangeable lenses or a zoom lens such as:
If you do have one of these types of camcorders you can affect the apparent depth of field by varying the focal length of the camera lens.
In other words, if you're using a zoom lens (for instance)...
And of course the reverse is true:
Simple...! This method of affecting the video composition depth of field is probably the least impactful of the three as normally you be shooting at a fixed focal length but...
If you're trying to control your depth of field very tightly it's a factor worth taking into consideration especially if you are shooting with a zoom lens.
Well... In my experience this is debatable and really doesn't have too much bearing on the controlling of the depth of field.
The other factors such as distance, focal length and aperture setting have a much greater bearing on this.
For those who say that the sensor does have some bearing on depth of field the datum most often quoted is:
In practice… I haven't seen that the size of the camera image sensor is much of a factor in controlling depth of field but… I will leave it up to you to verify that for yourself… (smile).
Sometimes it's hard to determine the video composition depth of field just by looking through the viewfinder or LCD screen.
In that case there are pocket guides that you can use to mathematically work out the depth of field using:
After you have the equation…
You be able to set up your camera and position it to achieve the desired video composition depth of field.
Most high-end camcorder lenses have markings on the lens barrel that will also assist you in determining depth of field. Most of the time however you'll be able to see (through the viewfinder or LCD screen) the sharpness front and back.
Knowing how to use video composition depth of field can be very valuable…
The creative use of video composition depth of field can be used to draw attention to people or objects in the frame.
The audience's attention can be guided exactly where you want it by the creative use of depth of field.
Here are just a couple of examples:
Another way to use controlled depth of field in your shot is…
You can have a lot of fun figuring out ways to use selectively controlling depth of field in your filmmaking or video production.
You can really control the audience's attention this way and make it much easier for them to follow the action.
Remember it's your point of view that counts as far as the use of focus and video composition depth of field.
This type of use of depth of field is subjective and is up to you the filmmaker or video producer as to how you use it and what sort of impact you want it to have on your audience.
Be creative and…Have some fun with it!
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