Shutter and exposure? at DVinfo.net

Jay Morrissette · November 1st, 2012, 04:25 PM

My video experience is limited. I'm used to having iris, and gain. I was taught that gain=grain, so don't use it, fix the lighting and iris instead.

Is exposure the same thing as gain?

What exactly does shutter do on a video camera?

This weekend I rented a vg-20 to film an interview, and an auto-x. What is the best setting for each of those things?

Thanks,
~Jay

Chris Barcellos · November 1st, 2012, 05:31 PM

Exposure is the amount of light reaching the chip. Exposure for a shot can be accomplished three ways:

Iris adjustment: The higher the F setting on the iris, the less light that is let in. In process, the higher the FStop, the deeper the depth of field in focus becomes.

Shutter speed. The faster (shorter time) the shutter is open, the less light that gets to imaging chip. Also the faster (shorter time) the shutter is open, the less motion blur there is. I try to shoot based on frame rate using a shutter speed have the frame rate. (24fps= 1/48 or 1/50, etc.) These rates will preserve some motion blur so you video does not have the stacatto effect that must fast shutter speeds have.

Gain or ISO adjustment. This actually adds electronic enhancement to the image to make it appear brigher. The higher the gain or ISO setting, the more the grain, is the general rule. However, under exposing a scene at a lower ISO or gain will also result in grain, sometimes less desirable grain than in a setting with higher gain.

Jay Morrissette · November 1st, 2012, 06:39 PM

thanks, that's very helpful

So in the case of the VG-120, is the exposure know equal to gain, or is it something different?

If I decide to shoot 1080p 60p for fast moving stuff, what is the ideal shutter speed?

thanks,
~Jay

Ryan Douthit · November 1st, 2012, 09:37 PM

If you plan on slowing the shot, you want to shoot cars at more than 1/180. I sometimes go as high as 1/1000. The worst you can do is go too low, as it will guarantee blurry slow-mo and just be okay. With cars higher is almost always better and try to keep it at ISO100. And yes, treat ISO like gain.

If you want to be more advanced, then you can go slower shutter speeds if your panning with the car. But any fast passing or locked shots should be much higher.

What Chris is talking about is more applicable to non-sports. With action sports faster shutter speed are almost always the better choice.

John Vincent · November 6th, 2012, 07:01 PM

Good tips Chris. I adjust shutter speed all the time to get more light to the sensor w/o raising the grain.

That said, Sony cameras - including the VG20 - are very good in the low light. You can jack the gain up quite a bit w/o adding an "offensive" amount of grain. It's one of the real strengths of Sony cameras.

November 1st, 2012, 04:25 PM	#1
Jay Morrissette Regular Crew Join Date: May 2009 Location: L.A. California Posts: 61	Shutter and exposure? My video experience is limited. I'm used to having iris, and gain. I was taught that gain=grain, so don't use it, fix the lighting and iris instead. Is exposure the same thing as gain? What exactly does shutter do on a video camera? This weekend I rented a vg-20 to film an interview, and an auto-x. What is the best setting for each of those things? Thanks, ~Jay

November 1st, 2012, 05:31 PM	#2
Chris Barcellos Inner Circle Join Date: Nov 2005 Location: Elk Grove CA Posts: 6,838	Re: Shutter and exposure? Exposure is the amount of light reaching the chip. Exposure for a shot can be accomplished three ways: Iris adjustment: The higher the F setting on the iris, the less light that is let in. In process, the higher the FStop, the deeper the depth of field in focus becomes. Shutter speed. The faster (shorter time) the shutter is open, the less light that gets to imaging chip. Also the faster (shorter time) the shutter is open, the less motion blur there is. I try to shoot based on frame rate using a shutter speed have the frame rate. (24fps= 1/48 or 1/50, etc.) These rates will preserve some motion blur so you video does not have the stacatto effect that must fast shutter speeds have. Gain or ISO adjustment. This actually adds electronic enhancement to the image to make it appear brigher. The higher the gain or ISO setting, the more the grain, is the general rule. However, under exposing a scene at a lower ISO or gain will also result in grain, sometimes less desirable grain than in a setting with higher gain. __________________ Chris J. Barcellos

November 1st, 2012, 06:39 PM	#3
Jay Morrissette Regular Crew Join Date: May 2009 Location: L.A. California Posts: 61	Re: Shutter and exposure? thanks, that's very helpful So in the case of the VG-120, is the exposure know equal to gain, or is it something different? If I decide to shoot 1080p 60p for fast moving stuff, what is the ideal shutter speed? thanks, ~Jay

November 1st, 2012, 09:37 PM	#4
Ryan Douthit Major Player Join Date: Feb 2006 Location: Kirkland, WA Posts: 474	Re: Shutter and exposure? If you plan on slowing the shot, you want to shoot cars at more than 1/180. I sometimes go as high as 1/1000. The worst you can do is go too low, as it will guarantee blurry slow-mo and just be okay. With cars higher is almost always better and try to keep it at ISO100. And yes, treat ISO like gain. If you want to be more advanced, then you can go slower shutter speeds if your panning with the car. But any fast passing or locked shots should be much higher. What Chris is talking about is more applicable to non-sports. With action sports faster shutter speed are almost always the better choice.

November 6th, 2012, 07:01 PM	#5
John Vincent Trustee Join Date: Sep 2005 Posts: 1,065	Re: Shutter and exposure? Good tips Chris. I adjust shutter speed all the time to get more light to the sensor w/o raising the grain. That said, Sony cameras - including the VG20 - are very good in the low light. You can jack the gain up quite a bit w/o adding an "offensive" amount of grain. It's one of the real strengths of Sony cameras.