December 14, 2006

1/3" HD's Dirty Little Secret
(previously titled "HDV's Dirty Little Secret")
What the 1/3" HD Manufacturers Don't Want You to Know

experience level: novice - anyone can benefit from knowing this

Summary

While 1/3" pro-sumer HD cameras nicely deliver on the promise of high-def imagery for the masses, that gift comes at a price - bad low-light performance.

Update - March 2007

I recently worked with the Canon XL-H1 (which I had not previously tested) on a feature shoot and found myself rating it at 250ASA.

All cinematographers want to know some basic capabilities of their recording medium, whether it be a film emulsion or digital video.  These include, amongst others, sensitivity, contrast latitude, and colorimetry.  While Panasonic, Sony, JVC, and Canon make much ado about the beautiful images their pro-sumer 1/3" HD cameras can produce (and rightly so) they studiously avoid any mention of how sensitive their cameras are.  And the reason is;

1/3" HD cameras are SLOW!

That's photographer-speak for slow to respond to light, as in needing LOTS of light to get a proper exposure.  I have personally tested and shot with the JVC GY-HD100, Panasonic HVX-200, and Sony HVR-Z1U and was dismayed to discover they share one trait in common.

1/3" HD cameras' are only 125ASA!

With their settings at factory default and 0dB gain, each of the HDV cameras I tested came in at an equivalent of only 125ASA using a tungsten light source.  That's all fine and good when shooting outdoors during the day, but when shooting an interior, HDV cameras need two times the light of a Canon XL-2 (320ASA), almost four times the light of a Panasonic AG-DVX100 at 60i (400ASA), and almost eight times the light of my venerable JVC GY-HD100 (800ASA).

Okay, so mediocre light performance is not such a big deal to me.  I own a one-ton lighting package and have the know-how to choose the lighting for film emulsions from Kodak's 5201 50ASA to their 5218 500ASA.  But, most buyers of HDV cameras don't.  To complicate matters;

1/3" HD cameras are noisy in the blacks!

All of the 1/3" HD cameras suffer from excessive noise in the blacks.  That means, if you underexpose your image for lack of sufficient light, you will suffer from excessive noise when you crank that image brighter in post.  (There are some "coring" functions on each of the cameras that can counter this.  Coring is your HD friend.)

Determining your Camera's ASA

tools: camera, 18% grey card, reflected spot light meter, light source

procedure:

• Point your camera and light at 18% grey card. (Place the light off-axis to avoid glare on card.)  As much as possible, assure an even illumination across the card.
• Adjust the camera's settings to desired defaults or creative choices.
• Turn on the camera's auto iris and note the f-stop reading.
• Set the spot meter to match camera's frame rate/shutter speed and take a reading.
• Adjust the spot meter's ASA until its f-stop matches that of the cameras f-stop. Seek a 1/2- to 1/3-stop accuracy, if possible.
• The meter's ASA reading now matches that of the camera.

Your camera may have different ASA ratings with daylight and tungsten light.  Many film stocks actually come with different ratings from the manufacturer.  Consider doing a test for each.

Know Your Camera

The bottom line here is:  Know what your camera can and can't do - including its equivalent ASA rating.   Once you know how well your camera responds to light, you are prepared to choose the right and sufficiently bright light for your shot.  to learn more about matching lights to cameras and film emulsions, read my article; Choosing the Right Lights for your Set.

Have fun out there! - Michael Morlan