Gabriel Rochette Posted February 26, 2007 Share Posted February 26, 2007 I'm looking for a real answer about f/stop (exposure) vs Lux. A kind of formula to be sure that the iris opening of the video camera is the best. I known the technique of ZEBRA but what is about this minimum LUX the do a sharp image without noise ? Thank you Gabriel Rochette Link to comment Share on other sites More sharing options...
Daniel Sheehy Posted February 27, 2007 Share Posted February 27, 2007 Hi, 'Minimum Lux' is a phrase most often seen in advertising material, it often has very little to do with good exposure. Link to comment Share on other sites More sharing options...
Premium Member Michael Nash Posted February 27, 2007 Premium Member Share Posted February 27, 2007 The "real" answer is to forget about lux. It means nothing in the real world of shooting. 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. Link to comment Share on other sites More sharing options...
Premium Member Andrew Koch Posted February 27, 2007 Premium Member Share Posted February 27, 2007 It's not practical to think in terms of lux unless you are dealing with very low lightlevels. One footcandle 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. Link to comment Share on other sites More sharing options...
Gabriel Rochette Posted February 27, 2007 Author Share Posted February 27, 2007 Thank you all for information about lux Gabriel Rochette Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now