View Full Version : Noise in the dark
When shooting dark footage the HV20 shows quite some noise in it's automatic mode. To prevent noise I want to shoot in manual mode but I was wondering what is causing the noise? The aperture or shutter speed? Or the combination ? :hv20-smilie51:
I just want to prevent noise. What can I do?
2007 July 20th, 07:56
Small sensors collect less light than larger sensors. Therefore, the picture they produce is necessarily darker. Shutter speed and aperture will make little difference as there simply isn't enough light falling on the sensor.
The only way to make the image brighter is to add gain (or electronic amplification). Unfortunately, this boosts everything, including noise. And that is wht you are seeing.
Shooting in progressive mode improves low light performance, but the noise will always be present to some extent.
Also, see this (http://www.hv20.com/showthread.php?t=180) thread.
2007 July 20th, 07:59
Add more lights! HDV cams are light hungry beasts, and the HV20 is just a pretty tame one.
Most likely source of noise is the gain. You can see what gain setting was used when you open your footage in a tool like HDVDataMon, the camera doesnīt show you this.
If you are comfy with a dark but noise-free image, you need to use the exposition lock feature. There a a few threads about this "trick". You lock the camera on a well-lit object and move it to your dark scene. The EXP lock prevents it from auto-changing the settings.
The HV20 can electronically enhance the signal by up to 27db, but you donīt really want it to do that.
Ah thanks for the quick reply! I tried the aperture/shutter speed hack and that works perfect. Just wanted to know what was causing the noise.
2007 July 21st, 09:22
GAIN was causing the noise
2007 July 21st, 12:14
While we're on the subject, has anyone done a test/experiment to see if using gain really is noisier than brightening the image in post? Theoretically, gain should actually produce higher quality, as it would be done before digitizing the pixel charges (or at least before reducing the bit depth to 8 bit). However, this would be negated by a noisy amplifier. I'd test it myself, but I don't have an HV20 yet (sigh...).
2007 July 21st, 14:52
Your better off recording in HDV24P with Cine mode for those low light shots as the image is excellent, IMO.
If I shoot a dark scene I capture it as a dark scene, NOT artificially brighten with cam gain and grain. If you want a brighter scene add lights; it's that simple.
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