T351 Lab #2

Agenda

• Camera followup / advanced tips
• Continuity
• Storyboard & Continuity sequence exercise

 

Misc. Announcements

• Don't forget to stay on top of the readings. If you need to find out anything about class, labs or assignments, please check the web site first. I'm happy to answer your questions and emails, but please make sure the information isn't already posted on-line.
• Start thinking and planning your various projects. Planning and scripting these ahead of time is critical to success. The first ones coming up are your Interview / feature story and Art Video.

Camera 202

Exposure - It would be nice if you could use a light meter to measure every scene or have a waveform monitor to check for proper video levels. The reality is that videographers rarely carry these tools (and many don't know how to use them). Still you must strive to shoot video that's properly exposed.

Waveform monitor and IRE units - A standard waveform monitor shows brightness (or luminance) levels in IRE units. Within the "legal" range, you have up to 100 IRE units. 0 IRE is digital black and 100 IRE is the brightest white.

Using the camera's built-in auto iris can be useful at times, but not always. If you are going to rely on it, you must know how it works. Think about how it looks at a scene and be aware of its limitations. For example if you were shooting a person against a light background (the sky for instance) it would close the iris down too far. You can zoom in to your subject so that they fill most of the screen, set your iris, and then zoom out. This may cause your background to be overexposed.

Zebra strips are a visual aid that show brightness levels- and they only appear in the viewfinder.

Always check the filter & WB before each new location or lighting situation.

Make sure the gain isn't turned on.

Allow for at least 5 seconds of pre-roll before your action starts and a few seconds of post-roll after your shot concludes. You will need this for the edit.

Major parts of video cameras: lens, beam splitter, CCDs/CMOS, & viewfinder

The lens focuses the light onto an imaging or pickup device. In the old days these were tubes, these days CCDs (Charge Coupled Device) or CMOS (Complementary Metal-Oxide Semiconductor) sensors are used.

Most professional video cameras that have CCDs use a beam splitter, which consists of prisms. The incoming light is split into its primary components, Red Green & Blue and recorded onto three separate CCDs. The CCDs are about the size of a postage stamp and convert the light energy into an electric charge. Before CCDs, cameras used tubes. However a growing number are using single CMOS sensors. CMOS sensors use less power than CCDs.

CCD and CMOS sensor sizes

Most sensors are made in different sizes such as 1/4", 1/3", 1/2", and 2/3". Some of the new HD video cameras use larger CMOS sensors that more closely match standard film sizes such as 35mm. This allows DPs to use their existing collection of 35mm lenses and attachments.

Consumer cameras usually have only one pickup device or three very small CCDs. (1/4" for example.) As the price and quality goes up, so does the size of the CCD. Professional studio cameras generally have larger CCDs. (The Canon HLX1 and Sony Z1U use 1/3" CCDs while the Grass Valley cameras in Studio 5 use 2/3" CCDs.) Lens mounts are standardized and matched to the corresponding CCD size. (You'd use a 2/3" lens mount with a camera with 2/3" CCDs.) The bigger the lens mount, the bigger the CCD and the more room for more pixels. Generally speaking, bigger is better and the more pixels a CCD or CMOS sensor has on it the higher the resolution or detail that can be delivered by the camera.

Camera / lens review:

• CCD - Charge Coupled Device (video imaging device)
• CMOS - Complementary Metal-Oxide Semiconductor (video imaging device)
• Resolution (Horizontal resolution is determined by the maximum number of vertical lines resolved. Requires a test chart.) The studio camera heads can resolve about 700 lines. VHS tape can only resolve about 230 lines.
• Gain (boosts signal and adds noise)
• Focal length: (Don't confuse with depth of field!) the distance from the optical center of the lens to the focal plane (CCD or target) of the camera). When focused at infinity, a10 mm lens will be 10 mm from the film plate or CCD.
• Zoom lens
• Angle of view (Telephoto lenses have narrow angles of view, while wide angle lenses have wide, or large angles of view.
• Zoom ratio: Often given in a ratio or two numbers (eg 12 x 10) The first number represents the minimum focal length in millimeters, and the second number the multiplier. A 12 X 10 zoom lens would have a minimum focal length of 12mm and a maximum focal length of 120mm.
• Compressing distance: telephoto lenses provide the effect of compressing distance
• Changes in apparent speed: Telephoto lenses also have the effect of slowing down Z motion. (The Z vector is directly in-line with the lens- as opposed to up and down or let to right.)
• Perspective changes - Wide angle lenses can cause distortion
• “What is normal” A normal lens won't cause visible distortion. To calculate the normal lens, measure diagonally from corner to corner. (eg a 50 mm lens would be "normal" for a 35 mm camera.
• Lens speed - lenses which let lots of light in (have small apertures) are said to be "fast". Lenses which have large apertures (don't let much light in) are said to be "slow".
• F-stop - inversely related to aperture or iris opening
• Depth of field - the range of distance that objects will be in focus
• Relationship between depth of field and f-stop - the higher the f-stop (smaller aperture) the greater the depth of field you will have.
• Relationship between lenses and depth of field - wide lenses will have a greater depth of field than telephoto lenses.
• Selective focus (related to rack focus and follow focus)
• Follow focus
• Rack focus
• Macro focus
• Auto focus (problems with)
• ND filters - Neutral density filters don't influence the color temperature. They are gray and translucent. There purpose is to minimize the light coming into the camera.

Viewfinders

Why B & W viewfinder and not color?

The number of pixel elements in a CRT or LCD display determines the resolution. More pixels = greater resolution, right? Color monitors need phosphors for each of the Red, Green and Blue elements, where black and white monitors only need one. So given the same size monitor or viewfinder, a black and white monitor will have 3 times more resolution than a color monitor. Since we are primarily concerned with framing and focus when we shoot, it's best to use the monitor or viewfinder with the sharpest display, which in most cases will be B & W.

Make sure you know how to:

• Set brightness and contrast
• Use the focus ring
• Flip open eyepiece
• Turn the tally light on and off

Setting proper aperture

Monitors are nice but never trust them until you see color bars through it first. The same applies for viewfinders. Always check out the appearance of color bars through your viewfinder before manually adjusting the iris.

Know how to set proper exposure using zebra stripes. Zebra stripes become visible when a certain IRE (brightness) level is reached. This brightness lavel can usually be set through the camera menu. Don't use zebra stripes unless you know what they are set for.

Shutter - Press once will engage shutter in either step or variable mode. Variable is what you use to get rid of scan lines on computer monitors. To change from step to variable, you need to access the camera menu, done by pressing in the status button for more than a second.

Zebra - The front switch has two settings, both of which can be preset. The on-off switch is to show zebra bars in the viewfinder. This level can be set in the setup menu. The momentary switch position shows the area set for skin detail. This can be changed in the process menu. It supposedly makes skin look gentle & smooth. (erases wrinkles)

Auto Iris Level: back (opens 1 step), normal or spot (closes 1 step)

Black Stretch: Stretch (improves contrast in dark portion) Use in high contrast setting to improve dark detail. Normal, or compress (gain of dark areas is compressed) Use the last setting for shooting in light, low contrast settings

FAS button (Full Auto Shooting) automatically adjust iris and white balance. Don’t trust it. If you are in FAS mode, you can't white balance.

Auto Knee: affects the visual dynamic range. Generally leave it off. Use it when shooting subjects against a very bright background. Improves contrast in these cases.

NG (no good)

Menu Settings:

VF display:

• Changing markers
• Turning phantom power on and off
• Shutter- Need variable for shooting computer monitors. Otherwise you want it on step.

Continuity Style Shooting vs Technical Continuity

Continuity Style Shooting

Readings from cybercollege.com: 50, 51 & 52 (all about continuity)
#1 rule: maintain continuity. Preserve the illusion of space & time. People and objects remain faithful to their positions (this can be tricky over days of shooting)

Edits must be motivated for the best continuity. When shooting think about how you will get from one shot to another. Will action motivate the edit? A sound?

Viewers create mental maps of where things are and expect time to progress forward.

A Master Shot, which is often a wide shot, establishes the initial relationship of people and things within a given scene or location. You can preserve this illusion by using the 180-degree rule when you shoot.

Review the 180-degree rule. (two people sitting at a table)

How to cross the line:

• Subject changes attention or move gaze to establish a new vector.
• Shoot down the line
• Subject moves
• Move the camera over line (dolly, crane etc)
• Use a cutaway, then come back to your scene from a different vantage point

Viewers are used to seeing the rule broken

Insert shots – close up from a larger shot

Cutaways – cut away to something related (could be something happening simultaneously)

Technical Continuity

Unplanned changes in sound, lighting, video or setting is referred to as a technical continuity problem.

Moviemistakes.com has lots of fun examples of technical continuity problems.

A famous one is in T2, when the T2 liquid robot cop is chasing Ahnuld and little John Conner. The T2 is driving a semi, Ahnuld & John are on a motorcycle down in a drainage canal. The T2 drives the semi off of the overpass down into the canal, and we can clearly see the windshield popping out. In the next shot of the front of the semi, the glass is back in the semi. That's an example of a technical continuity problem.

While your productions are not likely to suffer from an elaborate problem such as this, beware of common mistakes:

• Changes in color temperature. Avoid mixed lighting locations and white balance whenever you change the locations.
• Changes is light levels Keep lighting levels consistent within a scene.
• Primary Audio - use the same mic, in the same manner when recording your talent. (Don't use a lav in one scene and a handheld on a stand in another)
• Background audio - avoid abrupt changes within the same scene. Always record 60 seconds of ambient sound, which you can layer in to the audio mix.

TECHNICAL CONTINUITY

• Physical Continuity - props & clothing change from shot to shot. If your talent has sunglasses on in one shot, they need to be on in the next shot.
  • Have one crew person watch for these potential problems.
• Time Continuity - if a clock, candle or position of the sun appears in more than one shot, the time must be consistent with the scene.
  • Keep references to time out of the scene. Try to shoot scene under similar lighting conditions.
• Technical Continuity - shots don’t match in image quality or sound.
  • Make sure filter is set, microphone is working, etc.
• Event Continuity - The same person in two consecutive shots and has changed “magically” from one action to another.
  • Have the frame clear before and after each action to provide time to cut. Cut on action and overlap your shooting.

Storyboard / Action sequence exercise

Review storyboards

In addition to shooting the shots specidifed in your storyboard, shoot a final static “beauty” shot, which you may use to roll credits over at the end of your production. You may want to thematically link this last shot to your sequence.

You will shoot these today and edit them on Thursday.

You will be graded on the following:

• 6 – 8 frame storyboard (includes a one line description)
• Framing, blocking & continuity
• Production & editing
• Your critique

The finished program & critique are due at the beginning of Tueday's lecture.

 

Back to Jim Krause's T351 Home Page