A1 having Gain/WB Problem ( Not AGC) Under Multiple Lights at DVinfo.net

Declan Casey · October 13th, 2007, 05:51 PM

Hi All,

I'm currently in the process of filming a training video for a hair salon. I'm using two A1s. Both have gain L set to -3db. When I went to review the first days footage there seems to be a large amount of "fluxing" gain or grain in the image. The salon we're filming in has lots of lights, some flouresent, some halogen spots and some normal Tungsten incandencents so I did try to manually set the WB with a 100 IRE card. The image I'm getting is washed out, the blacks look gray and everything is grainy. Does anybody have any ideas of CPs to try and combat this?
I've uploaded a 4 second clip ( shot at 25F and imported to FCP at 1080p25, exported to 720p H264). If you look at the black in it you should see what Im talking about.

http://fyp.ie/declan/XH-A1%20Grain%2...20p%20H264.mov

Any help would be greatly appreciated

Declan

Bill Pryor · October 13th, 2007, 06:03 PM

Clip doesn't work; I go this:

The requested URL /declan/XH-A1 Grain%2...20p H264.mov was not found on this server.

Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.

Apache/1.3.37 Server at fyp.ie Port 80

If things look grainy that's usually an indication of shooting on a higher gain. Are you sure all the auto stuff is off and you're in the manual mode, not one of the auto ones?

Chris Soucy · October 13th, 2007, 06:09 PM

That link won't even persuade Explorer to get out of bed.

CS

Taylor Rudd · October 13th, 2007, 07:15 PM

try this link:

http://fyp.ie/declan/XH-A1%20Grain%2...20p%20H264.mov

Declan Casey · October 13th, 2007, 08:08 PM

Links is fixed now, sorry about that

Declan

Eric Weiss · October 15th, 2007, 12:09 PM

yeah, i see it in the dark areas. that's actually pretty typical for HD.
turn on any hdtv channel and you will see it. reds and dark browns will do it.

you will need to magnify and check those types of colors for noise before you shoot. sometimes you can correct the exposure and tone it down.

the shot is a little underexposed on the subjects and you have that light in the back shining right through them. i think that might be the reason too.

if you are using auto exposure, it's going to underexpose the subjects and properly expose the light.

regardless, i find it acceptable. with those two girls in the front, nobody is looking at the wall.

Meryem Ersoz · October 15th, 2007, 12:39 PM

i'd set the gain to 0 for indoor shooting, -3 is really for outdoor shooting with the HMI in the sky. adding gain seems counter-intuitive to solving a noise issue, but it might help smooth things out a bit...

Don Palomaki · October 15th, 2007, 05:44 PM

Quote:

... nobody is looking at the wall...

Well, at least no red-blooded guy will look at the wall.

I would suggest that you address the bright back light from the window(?) and the overhead lights, unless you are trying to obtain that effect.

October 13th, 2007, 05:51 PM	#1
Declan Casey Tourist Join Date: Nov 2006 Location: Cork, Ireland Posts: 2	A1 having Gain/WB Problem ( Not AGC) Under Multiple Lights Hi All, I'm currently in the process of filming a training video for a hair salon. I'm using two A1s. Both have gain L set to -3db. When I went to review the first days footage there seems to be a large amount of "fluxing" gain or grain in the image. The salon we're filming in has lots of lights, some flouresent, some halogen spots and some normal Tungsten incandencents so I did try to manually set the WB with a 100 IRE card. The image I'm getting is washed out, the blacks look gray and everything is grainy. Does anybody have any ideas of CPs to try and combat this? I've uploaded a 4 second clip ( shot at 25F and imported to FCP at 1080p25, exported to 720p H264). If you look at the black in it you should see what Im talking about. http://fyp.ie/declan/XH-A1%20Grain%2...20p%20H264.mov Any help would be greatly appreciated Declan Last edited by Declan Casey; October 13th, 2007 at 08:07 PM.

October 13th, 2007, 06:09 PM	#3
Chris Soucy Inner Circle Join Date: Feb 2007 Location: Fairfield, Dunedin, New Zealand Posts: 3,682 Images: 18	Hi Declan.............. That link won't even persuade Explorer to get out of bed. CS

October 13th, 2007, 08:08 PM	#5
Declan Casey Tourist Join Date: Nov 2006 Location: Cork, Ireland Posts: 2	Link Fixed Links is fixed now, sorry about that Declan

October 13th, 2007, 06:03 PM	#2
Bill Pryor Contributor Join Date: Jan 2003 Location: Kansas City, MO Posts: 4,449	Clip doesn't work; I go this: The requested URL /declan/XH-A1 Grain%2...20p H264.mov was not found on this server. Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request. Apache/1.3.37 Server at fyp.ie Port 80 If things look grainy that's usually an indication of shooting on a higher gain. Are you sure all the auto stuff is off and you're in the manual mode, not one of the auto ones?

October 13th, 2007, 07:15 PM	#4
Taylor Rudd New Boot Join Date: Sep 2007 Location: Waco, Texas Posts: 6	try this link: http://fyp.ie/declan/XH-A1%20Grain%2...20p%20H264.mov

October 15th, 2007, 12:09 PM	#6
Eric Weiss Major Player Join Date: Mar 2007 Location: Philly,PA Posts: 360	yeah, i see it in the dark areas. that's actually pretty typical for HD. turn on any hdtv channel and you will see it. reds and dark browns will do it. you will need to magnify and check those types of colors for noise before you shoot. sometimes you can correct the exposure and tone it down. the shot is a little underexposed on the subjects and you have that light in the back shining right through them. i think that might be the reason too. if you are using auto exposure, it's going to underexpose the subjects and properly expose the light. regardless, i find it acceptable. with those two girls in the front, nobody is looking at the wall.

October 15th, 2007, 12:39 PM	#7
Meryem Ersoz Wrangler Join Date: Jan 2005 Location: Boulder, CO Posts: 3,015	i'd set the gain to 0 for indoor shooting, -3 is really for outdoor shooting with the HMI in the sky. adding gain seems counter-intuitive to solving a noise issue, but it might help smooth things out a bit...