GL2 Exposure changes when panning from bright to low light at DVinfo.net

Michael Botkin · March 18th, 2003, 08:53 PM

Probably a stupid question, but I recently was shooting a few trains in a train yard during a sunset. I was in FULL MANUAL mode on the GL2 and started panning from a woods shot toward the cloudbreak in the sky shich contained the sunset. Keep in mind this is all on the horizon. When going from the dark clouds to the bright sunset, the exposure changed dramatically and darkened the clouds beyond belief. I was under the impression with full MANUAL mode that the exposure should not change, no matter what the light source. Now I know there is an "exposure lock" option, but that seems to only be available in the Shutter/Aperture settings. Any ideas? Am I an idiot to think that this should not happen? I can post a vid if someone can host. Thanks again,

Michael Botkin

Ken Tanaka · March 18th, 2003, 11:27 PM

Michael,
Aside from judging the image in the viewfinder, did you actually see the iris and shutter speed figures change in the viewfinder display?

Jeff Donald · March 19th, 2003, 05:21 AM

I'm not exactly sure I'm following the course of your events. But if you are in manual you should notice the scene get lighter or darker if the light value in you scene changes. This can be due to panning (as you did) or a change in lighting (sun moving behind clouds etc.). The camera uses (in an auto or program mode) the aperture and or shutter speed to keep the relative light value reaching your chip (CCD) the same level. By controlling the aperture and shutter speed the camera can adjust the exposure to maintain a relative level of exposure during pans and changing light conditions.

Putting the camera in manual and setting proper exposure for a specific scene and then panning will usually cause the exposure to change (scene gets too light or too dark) because of the inability of the camera to automatically compensate for light level changes.

Michael Botkin · March 19th, 2003, 09:08 AM

Let me review the tape tonight and see if the shutter/aperture changes when the scene became lighter. Anyone able to host a clip? Or can I somehow upload it on the forum?

Michael

Brian M. Dickman · March 19th, 2003, 09:24 AM

Did you happen to hear a click and see "ND" come on in the display? I haven't checked myself, but it's possible that the ND filter will get automatically activated (and I kind of think I've seen it happen) even in full manual mode when you go to extremely bright conditions that the camera feels it can't handle.

Anyone else confirm this, or have seen an entry in the manual to indicate this could happen? I know I've seen the ND filter switch on automatically before in bright sun, but I forget if I was in full manual or not.

Adrian van der Park · March 19th, 2003, 10:13 AM

make sure that your gain is not in auto mode.

I've been burnt by that in the past more than once on XL1 and GL1.

On my XL1, I put a dab of hotglue to keep the knob locked at 0 gain.

Ken Tanaka · March 19th, 2003, 10:22 AM

Brian,
I don't think the ND filter can self-engage, although it's easy to inadvertently press its button.

Adrian, the gain operates differently on the GL2 than on the XL1/XL1S. There is no physical dial, but rather a digital setting that appears when Manual mode is engaged. (There are also color gain sliders buried in a menu.)

Alex Dunn · April 1st, 2003, 11:12 AM

The GL2 in Auto Mode (that's what you said right?) will always adjust the exposure as you pan from one light level to another. That's why it has the Manual capability, to lock in the exposure you want. The key is to "plan your pan". Before you start rolling, pan to the sunlight and set your exposure, then pan to the clouds and set again. Repeat steps until you find a middle ground that looks good all the way through the pan.

No, the ND Filter will not self-engage, however it will flash on the viewfinder when it thinks you SHOULD be using it and aren't.

March 18th, 2003, 08:53 PM	#1
Michael Botkin Regular Crew Join Date: Dec 2002 Location: Cary, NC Posts: 70	GL2 Exposure changes when panning from bright to low light Probably a stupid question, but I recently was shooting a few trains in a train yard during a sunset. I was in FULL MANUAL mode on the GL2 and started panning from a woods shot toward the cloudbreak in the sky shich contained the sunset. Keep in mind this is all on the horizon. When going from the dark clouds to the bright sunset, the exposure changed dramatically and darkened the clouds beyond belief. I was under the impression with full MANUAL mode that the exposure should not change, no matter what the light source. Now I know there is an "exposure lock" option, but that seems to only be available in the Shutter/Aperture settings. Any ideas? Am I an idiot to think that this should not happen? I can post a vid if someone can host. Thanks again, Michael Botkin

March 18th, 2003, 11:27 PM	#2
Ken Tanaka Retired DV Info Net Almunus Join Date: Dec 2001 Location: Chicago, IL Posts: 6,943	Michael, Aside from judging the image in the viewfinder, did you actually see the iris and shutter speed figures change in the viewfinder display? __________________ Lady X Films: A lady with a boring wardrobe...and a global mission. Hey, you don't have enough stuff! Buy with confidence from our sponsors. Hand-picked as the best in the business...Really! See some of my work one frame at a time: www.KenTanaka.com

March 19th, 2003, 05:21 AM	#3
Jeff Donald Warden Join Date: Mar 2002 Location: Clearwater, FL Posts: 8,287	I'm not exactly sure I'm following the course of your events. But if you are in manual you should notice the scene get lighter or darker if the light value in you scene changes. This can be due to panning (as you did) or a change in lighting (sun moving behind clouds etc.). The camera uses (in an auto or program mode) the aperture and or shutter speed to keep the relative light value reaching your chip (CCD) the same level. By controlling the aperture and shutter speed the camera can adjust the exposure to maintain a relative level of exposure during pans and changing light conditions. Putting the camera in manual and setting proper exposure for a specific scene and then panning will usually cause the exposure to change (scene gets too light or too dark) because of the inability of the camera to automatically compensate for light level changes. __________________ Jeff Donald Carpe Diem Search DVinfo.net for quick answers \| Where to Buy? From the best in the business: DVinfo.net sponsors

March 19th, 2003, 10:13 AM	#6
Adrian van der Park Regular Crew Join Date: Sep 2002 Location: London, England Posts: 87	make sure that your gain is not in auto mode. I've been burnt by that in the past more than once on XL1 and GL1. On my XL1, I put a dab of hotglue to keep the knob locked at 0 gain. __________________ Adrian van der Park VFX modeler London, England

March 19th, 2003, 10:22 AM	#7
Ken Tanaka Retired DV Info Net Almunus Join Date: Dec 2001 Location: Chicago, IL Posts: 6,943	Brian, I don't think the ND filter can self-engage, although it's easy to inadvertently press its button. Adrian, the gain operates differently on the GL2 than on the XL1/XL1S. There is no physical dial, but rather a digital setting that appears when Manual mode is engaged. (There are also color gain sliders buried in a menu.) __________________ Lady X Films: A lady with a boring wardrobe...and a global mission. Hey, you don't have enough stuff! Buy with confidence from our sponsors. Hand-picked as the best in the business...Really! See some of my work one frame at a time: www.KenTanaka.com

March 19th, 2003, 09:08 AM	#4
Michael Botkin Regular Crew Join Date: Dec 2002 Location: Cary, NC Posts: 70	Let me review the tape tonight and see if the shutter/aperture changes when the scene became lighter. Anyone able to host a clip? Or can I somehow upload it on the forum? Michael

March 19th, 2003, 09:24 AM	#5
Brian M. Dickman Regular Crew Join Date: Sep 2002 Location: Portland, OR Posts: 148	Did you happen to hear a click and see "ND" come on in the display? I haven't checked myself, but it's possible that the ND filter will get automatically activated (and I kind of think I've seen it happen) even in full manual mode when you go to extremely bright conditions that the camera feels it can't handle. Anyone else confirm this, or have seen an entry in the manual to indicate this could happen? I know I've seen the ND filter switch on automatically before in bright sun, but I forget if I was in full manual or not.

April 1st, 2003, 11:12 AM	#8
Alex Dunn Major Player Join Date: Aug 2002 Location: Phoenix, AZ Posts: 202	The GL2 in Auto Mode (that's what you said right?) will always adjust the exposure as you pan from one light level to another. That's why it has the Manual capability, to lock in the exposure you want. The key is to "plan your pan". Before you start rolling, pan to the sunlight and set your exposure, then pan to the clouds and set again. Repeat steps until you find a middle ground that looks good all the way through the pan. No, the ND Filter will not self-engage, however it will flash on the viewfinder when it thinks you SHOULD be using it and aren't.