minimum lux for top exposure
Posted 26 February 2007 - 06:54 PM
Posted 26 February 2007 - 10:45 PM
'Minimum Lux' is a phrase most often seen in advertising material, it often has very little to do with good exposure.
Posted 26 February 2007 - 11:27 PM
You get noise in the image when the image is underexposed and you amplify it in post, or amplify the image in camera by adding gain. A dark image in camera without added gain is just a dark image. There's no more inherent noise in an underexposed image than a "properly exposed" one. Make sure any "auto gain" controls in the camera are turned off, and the gain is set to zero db.
Posted 27 February 2007 - 01:32 AM
is equal to 10.764 lux (usually rounding down to 10 works fine and it's a heck of a lot easier to do the math). Even with fast 500 ASA film at a 1.4 tstop, you need at least 5 footcandles for "normal exposure." The difference of exposure between units smaller than a footcandel becomes exponentially less significant as you increase your light levels.
I find it more useful to find a relationship between IRE units and your camera's tstops. This relationship is ofcourse dependent on the ISO of the film or the camera. Since you are talking about "zebras" I can only assume you are talking about video cameras.
To determine the ISO of your camera at a particular white balance, filter, gain, etc... setting, you need to use a waveform monitor.
This way you can use the waveform monitor with a lighteter to establish a relationship with fstops and IRE.
If the ISO of your camera is etremely high, like 2000 ISO for example, you could use lux for contrast levels for extremely dark parts of your scene, but I wonder if this is a realistic situation.
Maybe in the future, if cameras get ridiculously sensitive, lux might be more useful.
I hope this was helpful.
Posted 27 February 2007 - 12:56 PM