The HV20/30/40 camera series from Canon is very popular amongst the indie filmmaker crowd.  Priced well under $1000, these cameras are easily affordable by filmmakers who follow the ‘own the means of production’ philosophy of film making.  Sporting features such as hdv and 24p, the camera series was an instant hit and continues to attract followers as can be seen by the frequent traffic at hv20.com.

Challenging Dark Scenes

One of the big challenges for consumer and prosumer cameras is low light situations.  These cameras are optimized to work in daylight settings.  Although these cameras are often used indoors, all too often indoor environments are generally low light conditions.

High end cameras allow the operator to completely control the camera through manipulating settings such as the aperture, shutter speed, neutral density (ND) filter, and gain.  A skilled cinematographer will know how to set the camera to optimize the exposure for the given light conditions.  However a consumer camera, such as the Canon HV30, often makes those decisions for the user.  From reading the HV30 manual, it appears that users may control the aperture or the shutter speed, but not both.  There is no user control for the gain and the ND filter.

For the most part, this is fine for a consumer since they just want to turn on the camera, press the record button, and compose scenes.  However, added gain can make the video very grainy which poses a problem for filmmakers looking to do post work on the film.  In general, indie filmmakers want to minimize video noise, and therefore gain.  So if the HV30 does not allow users to control the gain, what should filmmakers do?

Lock Exposure with White Image

It turns out a number of individuals have been contemplating this issue, and have posted solutions in threads on hv20.com.  Another good resource is the article written by Barry Green.  The idea centers around the fact that if one locks the exposure in manual mode, then one can adjust the aperture around that locked exposure.  However, the HV30 will choose the initial locked exposure based on the ambient lighting values.  That means one could have a different set of exposure values every time the camera is locked.

The solution is to lock the exposure with a fixed light source.  The Barry Green article suggests using a white image stored on a cell phone.  In my case, I used a white image stored on my Canon G9.  One holds the white image up to the HV30 lens so that the camera only sees white.  This allows one to lock the exposure in a repeatable manner.  It also sets up a range of exposures without any gain or changes in shutter speed.  Using this initialization procedure, I can consistently setup the exposure range and then shoot scenes without having to worry about the camera adding gain or manipulating shutter speed.

The following video shows the first ten seconds of a dark scene shot on Auto.  Although the video doesn’t look too bad, the HV30 used gain and adjusted the shutter speed to brighten the shot.  The second ten seconds was shot with the exposure locked as described earlier.  This part of the clip is noticeably darker but added no gain and did not adjust the shutter speed.  This is encouraging to indie filmmakers since the goal is to maintain a 1/48 shutter speed (when shooting 24p) as well as minimizing video noise produced by excess gain.

Canon HV30 Exposure Test from Fourth Order Light on Vimeo.