Can I Adjust Video Gain AGC Sensitivity at DVinfo.net

Stephen Cavaseno · October 11th, 2009, 06:19 PM

In Auto mode, my SONY Z5U raises the gain unnecessarily. On the first wedding we shot, the camera kicked the gain up to over 20dB even when using my 50 watt light, because the backgrounds were dark (guests arriving at night). I adjusted the AGC limit to 6dB, but then the camera still quickly kicks it up to 6dB when it is not needed, and on the rare occasion that the scene actually requires a gain of 12dB, it can't go that high because I set the linit to 6dB. Is there any way to make the Auto Gain Control less sensitive? In other words in full auto mode I don't want the camera to raise the gain unless the scene is darker.

Don Bloom · October 11th, 2009, 07:53 PM

DELETED -operator error in response. Sorry!

Jeff Harper · October 12th, 2009, 09:24 AM

If you set the AGC, that should do what you need, not sure what is happening. I shoot with mine set at 9dB and it works out well.

Rob Morse · October 12th, 2009, 09:50 AM

Just shoot in manual and call it a day. There is no other way to adjust the gain unless you manually change the AGC limit.

Adam Gold · October 12th, 2009, 08:55 PM

Quote:

Originally Posted by Stephen Cavaseno

Is there any way to make the Auto Gain Control less sensitive?

Sure. Just play around with AE SHIFT. Page 71.

But Jeff's right. Set AGC LIMIT to 9, then set your three manual gain levels to 12, 15 and 18. Keep the switch on the L position by default. Then if you find you need more gain when you're in AUTO, hit the gain button and you can ratchet it up as necessary, then go back to AUTO for the next shot.

Make sure HYPER GAIN is OFF.

And you can do all these things together; it should take care of your problem.

Jeff Harper · October 12th, 2009, 10:04 PM

I should submit that I used to complain about the camera's having a grainy look in low light but the issue was I was not using the cam properly. Since lowering the AGC, I have found a dramatic improvement in my images. If 9db isn't enough I use more light (my problem was usually during dark receptions) or I get as close to subject as possible. If those things don't work or are not possible then I ratchet the gain up to 12db and that works out fine also.

Tom Hardwick · October 16th, 2009, 11:52 AM

Also when light levels drop keep to wide-angle Jeff. You can film in one third the light at wide than in tele as the lens loses a good solid 2 stops as you zoom.

Jeff Harper · October 16th, 2009, 11:54 AM

Thanks Tom, learned that pretty quickly!

Tim Akin · October 22nd, 2009, 10:50 AM

What I like to do when I want to control the gain manually, is set the gain limit to 0db and set the AE Shift to -5, set the three manual gain switches to 3, 6, and 9. This gives me 5 switchable settings.

Jeff Harper · October 22nd, 2009, 11:06 AM

Tim, I forgot about the AE shift...can you remind me what it does and how it's used? I had played with it a few times and forgot about it for some reason...

Tom Hardwick · October 22nd, 2009, 11:11 AM

AE shift can be quite useful and I often have my unattended second camera running in full auto with a gain shift dialled in. Say I'm filming the speeches, bottom half of the frame is people, top half is white wall. In auto the camera woould under-expose the people, so I dial in +1.5 stops and all is well - the people brighten up and the wall goes white.

I can't lock the exposure because a) it's an unattended camera and b) the speeches might last an hour and light levels can change hugely in that time.

tom.

Jeff Harper · October 22nd, 2009, 11:51 AM

Thanks Tom. I also found an old thread where we discussed this...it seems I'm pulled so many directions that sometimes new info gets discarded before I have a chance to use it..

Tim Akin · October 22nd, 2009, 03:01 PM

Tom explained it better than I could have Jeff. But I use AE shift with exposure set to manual and gain set to auto. If the auto gain goes from -3 to 0db and I don't want it too I can hit AE shift and get it back to -3....unless there's not enough light.

Jeff Harper · October 22nd, 2009, 11:16 PM

Thanks Tim!

Tom Hardwick · October 23rd, 2009, 12:36 AM

Quote:

Originally Posted by Tim Akin

I use AE shift with exposure set to manual.

Tim's right, and I've used AE shift in combination with manual exposure when shooting on a dull day in snow. Generally cameras will under-expose in such conditions - the snow will go grey and people will look far too dark.

It goes like this. Dial in an AE shift of +1.5 stops, say. Now lock the shutter speed, w/bal, NDs and gain. Whenever you hit the iris button the camera will go back to auto and give you a reading. Second touch of that button locks in the new reading, and of course you always have fine adjust of this new setting under the iris wheel.

It works well. You're in manual (important) but you're not having to open up lots each time you 'ask the camera'.

tom.

October 11th, 2009, 06:19 PM	#1
Stephen Cavaseno New Boot Join Date: Oct 2009 Location: New York, New York Posts: 6	Can I Adjust Video Gain AGC Sensitivity In Auto mode, my SONY Z5U raises the gain unnecessarily. On the first wedding we shot, the camera kicked the gain up to over 20dB even when using my 50 watt light, because the backgrounds were dark (guests arriving at night). I adjusted the AGC limit to 6dB, but then the camera still quickly kicks it up to 6dB when it is not needed, and on the rare occasion that the scene actually requires a gain of 12dB, it can't go that high because I set the linit to 6dB. Is there any way to make the Auto Gain Control less sensitive? In other words in full auto mode I don't want the camera to raise the gain unless the scene is darker.

October 11th, 2009, 07:53 PM	#2
Don Bloom Inner Circle Join Date: Jan 2003 Location: Chicago, IL Posts: 6,609	DELETED -operator error in response. Sorry! __________________ What do I know? I'm just a video-O-grafer. Don

October 12th, 2009, 09:24 AM	#3
Jeff Harper Inner Circle Join Date: Jun 2005 Location: Cincinnati, OH Posts: 8,425	If you set the AGC, that should do what you need, not sure what is happening. I shoot with mine set at 9dB and it works out well. Last edited by Jeff Harper; October 12th, 2009 at 10:11 AM. Reason: Additional comment

October 22nd, 2009, 10:50 AM	#9
Tim Akin Major Player Join Date: Nov 2008 Location: Newbern, TN Posts: 414	What I like to do when I want to control the gain manually, is set the gain limit to 0db and set the AE Shift to -5, set the three manual gain switches to 3, 6, and 9. This gives me 5 switchable settings. __________________ Tim

October 22nd, 2009, 03:01 PM	#13
Tim Akin Major Player Join Date: Nov 2008 Location: Newbern, TN Posts: 414	Tom explained it better than I could have Jeff. But I use AE shift with exposure set to manual and gain set to auto. If the auto gain goes from -3 to 0db and I don't want it too I can hit AE shift and get it back to -3....unless there's not enough light. __________________ Tim

October 12th, 2009, 09:50 AM	#4
Rob Morse Major Player Join Date: Feb 2009 Location: Charlotte, NC Posts: 427	Just shoot in manual and call it a day. There is no other way to adjust the gain unless you manually change the AGC limit.

October 12th, 2009, 10:04 PM	#6
Jeff Harper Inner Circle Join Date: Jun 2005 Location: Cincinnati, OH Posts: 8,425	I should submit that I used to complain about the camera's having a grainy look in low light but the issue was I was not using the cam properly. Since lowering the AGC, I have found a dramatic improvement in my images. If 9db isn't enough I use more light (my problem was usually during dark receptions) or I get as close to subject as possible. If those things don't work or are not possible then I ratchet the gain up to 12db and that works out fine also.

October 16th, 2009, 11:52 AM	#7
Tom Hardwick Inner Circle Join Date: Mar 2003 Location: Billericay, England UK Posts: 4,711	Also when light levels drop keep to wide-angle Jeff. You can film in one third the light at wide than in tele as the lens loses a good solid 2 stops as you zoom.

October 16th, 2009, 11:54 AM	#8
Jeff Harper Inner Circle Join Date: Jun 2005 Location: Cincinnati, OH Posts: 8,425	Thanks Tom, learned that pretty quickly!

October 22nd, 2009, 11:06 AM	#10
Jeff Harper Inner Circle Join Date: Jun 2005 Location: Cincinnati, OH Posts: 8,425	Tim, I forgot about the AE shift...can you remind me what it does and how it's used? I had played with it a few times and forgot about it for some reason...

October 22nd, 2009, 11:11 AM	#11
Tom Hardwick Inner Circle Join Date: Mar 2003 Location: Billericay, England UK Posts: 4,711	AE shift can be quite useful and I often have my unattended second camera running in full auto with a gain shift dialled in. Say I'm filming the speeches, bottom half of the frame is people, top half is white wall. In auto the camera woould under-expose the people, so I dial in +1.5 stops and all is well - the people brighten up and the wall goes white. I can't lock the exposure because a) it's an unattended camera and b) the speeches might last an hour and light levels can change hugely in that time. tom.

October 22nd, 2009, 11:51 AM	#12
Jeff Harper Inner Circle Join Date: Jun 2005 Location: Cincinnati, OH Posts: 8,425	Thanks Tom. I also found an old thread where we discussed this...it seems I'm pulled so many directions that sometimes new info gets discarded before I have a chance to use it..

October 22nd, 2009, 11:16 PM	#14
Jeff Harper Inner Circle Join Date: Jun 2005 Location: Cincinnati, OH Posts: 8,425	Thanks Tim!