The lens

LENS, APERTURE, DEPTH OF FIELD, SHUTTER, WHITE BALANCE

The more you know about the lens, the functions of the lens, and the simple rules and configurations that you can set up with lens functions, the easier it will be to create the images you want.

 

Focal Length

The focal length of a lens refers to the distance from the center of the lens to the point on the image sensor where the image is in focus.

Focal length is measured in millimeters. For camcorders with optical zoom lenses, you can determine the magnification, or “x” factor of your camcorder by dividing the second number in the focal length by the first. For example, a camcorder with a 35mm-350mm lens would have a 10x optical zoom.

Wide Angle – A focal length below 39mm. Subject remains in focus closer to the lens and more distant objects appear out of focus.

Telephoto – A focal length of 85mm or more. Focuses on subjects at a distance.


Depth of Field

Depth of field refers to the area that remains in focus using a specific focal length. A wide angle shot of a scene at a distance has a greater depth of field than a telephoto shot of the same scene.

A Simple Guide to Depth of Field


Larger apertures (smaller F-stop number) and closer focusing distances produce a shallower depth of field.

apertures-effect-on-depth-of-fielddepth-field-collageAperturesdepth-of-field-bwmain-qimg-72fccc6d96f8dafa80734dff05dfcbc3-ccaption_007

Zoom Function and Changing Focal Length
Manual – zoom ring on lens zoom in and out carefully to avoid unwanted irregular zoom speeds. Zooming too fast may cause lag between zoom speed and camcorder lens pickup speed.

Zoom in – lens becomes a telephoto lens with a longer focal length (85mm, 105mm) and a shallower depth of field.

Zoom out – lens become a wider angle lens with a shorter focal length (28mm, 35mm, or 50mm) and deeper depth of field

Zoom lever responds to finger pressure – more pressure, faster zoom; less pressure, slower zoom

Handle “rocker” zoom – on top of handle
Set the speed using handle zoom controls on the camera

Handle zoom switch can be set to OFF so that you can only use manual or power zoom


Neutral Density Filter

Restricts the amount of light coming into the lens.

Use in very bright conditions because the ND filter suppresses light refraction common in video. Light refraction is a lightwave that separates and changes direction. Refraction appears as a prism or series of circles or reflections on the image.

Aperture/Iris
The iris controls the amount of light entering the lens. It can be adjusted for any type of lighting situation, or it can be closed entirely, letting no light in.


F-stop

The aperture settings are indicated by f-stop values. When the aperture is open, the f-stop value decreases, and when it is closed, the f-stop value increases.

An f-stop of 2.8 (written f/2.8) indicates a wide aperture, letting in more light. An f-stop of f/11 indicates a small aperture, letting in less light.

Aperture opening effects the sharpness of an image. A sequence shot at f11 will be sharper than a sequence shot at f/2.8. However, f/11 requires more light.

Auto – Set the AUTO/MANUAL switch to AUTO
Manual –In the camcorder menu > CAMERA SET > IRIS/EXPOSURE > IRIS
set the AUTO/MANUAL switch on the camcorder to MANUAL
use the iris/aperture ring to adjust setting manually

A Simple Explanation of F-Stop

. . . further explained here, but don’t worry about the math, just concentrate on the concept and the relationships described between aperture and f/stop value . . .

http://www.paragon-press.com/lens/lenchart.htm


Focus

Minimum focus distance
Wide angle: 1 cm
Telephoto: 80 cm (2-1/2 ft.)

Auto
Set focus switch on the side of the camcorder to AUTO

In manual focus, you can have the camcorder focus for you and remain in manual mode by temporarily holding the auto focus button.  The camera returns to manual focus mode when you release the button.

Manual
Set focus to manual mode MAN using switch on side of camcorder.
Always focus ahead of shot: zoom into your subject completely, focus it manually or use quick auto focus button, and then zoom out to desired focal length.


White Balance

colorwheel

Auto White Balance – Press the WHT BAL button; or set the AUTO/MANUAL switch to AUTO.
In the AUTO setting, iris/aperture, gain, and shutter speed also become automatic

Manual White Balance – Set the WHITE BAL button to MANUAL; hold a white card or opaque sheet of white paper close to the lens and press the WHT BAL button until the white balance icon stops flashing.

Storing White Balance Presets – Set the AUTO/MANUAL switch to MANUAL; set the Presets switch to A or B; hold a white card in front of the lens and press the round button next to Presets switch. This stores the value in whatever memory (A or B) you have the switch set to. Perform the same tasks using the second Preset switch (A or B). This is most useful when you are shooting both indoors and outdoors and can store presets for each shooting condition.


Shutter Speed

Shutter speed adjustments are made if your subject is moving very quickly (high shutter speed to capture fast movement) or, alternately, if they are in a low-light situation (low shutter speeds to capture more light).

One rule in normal lighting situations is that your shutter speed should be double your frame rate. Therefore, at 30fps, your shutter speed should be at 1/60. At 24fps, your shutter speed should be at 1/50th (some cameras don’t have a 1/48 option).

Rule of thumb regarding shutter speed
Once you have established the shutter speed for your film shoots, DO NOT CHANGE IT. You will want all of your footage to be shot at the same shutter speed, unless you are shooting some scenes in extreme circumstances.

Do not use Shutter Speed settings as a way to increase or decrease the amount of light going through the lens. Use aperture settings (f-stop) and external lights (daylight, studio light, or practicals) to give your scene the amount of light it needs.

Automatic Shutter Speed
Press the Shutter Speed button, or set the AUTO/MANUAL white balance button to AUTO.

Manual
To make a fast-moving subject remain in focus and reduce or eliminate blur, set the AUTO/MANUAL switch to MANUAL, press the SHUTTER SPEED button until shutter speed is displayed in viewfinder/LCD screen. Change the shutter speed by turning the SEL/PUSH EXEC dial Select values from ¼ to 1/10000 second. The number 100 appears in the viewfinder/LCD display, e.g. if you set the shutter speed to 1/100 second. Press the SEL/PUSH EXEC dial to lock in the shutter speed selected Shutter speeds lower than 1/24 will produce trails in the image.


 

 

Advertisements