"Ghost" vignetting at DVinfo.net

elusive_kudo · July 11th, 2002, 08:08 AM

I have a strange "problem" wih few scenes of my recorded footage and would appreciate any help with it.

Some of the footage I took with a widest setting on wide lens which came with my Sony PD 100a do show a small, but visible, what appears to be a vignetting effect in the upper left corner on my LCD screen when playing back. It's also there when I snap a still from those scenes, yet when I play the footage back on regular home TV (I've tried 3 different TV sets) it does not appear at all!!?

Does anyone knows what this is exactly and why is it the way it is?

Chet Hardin · July 11th, 2002, 10:06 AM

Hey --
Most likely that vignetting doesn't go away when you watch it on a tv screen. what goes away is the entire part of the recorded image that the vignetting apears in. i don't know the tech nical terms off the top of me head but what you are watching on the tv does not fully represent the complete aspect ratio of the image you recorded. it sounds like your cameras lcd screen does and that is why you see it on the LCD.

I don't understand what you mean "snap a still," do you print it out on your computer? actually, do you have access to a computer with any editing software or a production monitor? if so, then you would see the image with the full ratio the camera recorded.

You know, my XL-1's viewfinder doesn't show the full ratio and it is frustrating, especially when you film a girl getting her head chopped off and the mustard botttle that is squirting the blood can be seen in the bottom of the screen, unbeknownst to me until watching "dailies".

anyway.

elusive_kudo · July 11th, 2002, 01:02 PM

What I meant when I said that it shows also when I snap a still, meaning when I play back the footage or when I press freeze I can grab a snapshot by pressing "photo" button and record that particular freezed frame as a .jpg on my Sony memory stick. Then when I import that .jpg into my Photoshop, sure enough that ugly thing is visible there.

Is there any way to correct this problem in post or am I doomed?

Chet Hardin · July 11th, 2002, 01:54 PM

Do you have any filters attached to this lens?

elusive_kudo · July 11th, 2002, 03:01 PM

No, I do not. Just a rectangular hood, but I've tried without it and it still has the same effect so it is inside the lens where it is causing it, not outside. So, when I zoom in it goes away, but I found that I have to zoom in a bit more than just a dash, and that cuts on "wide angle" purpose.

Charles Papert · July 11th, 2002, 05:43 PM

When you refer to the "wide lens" that came with your camera, do you mean you are using a screw-on wide angle adaptor? If so, it may be a third-party product that was not designed for the camera, and thus does not offer full coverage of the CCD, thus you are experiencing vignetting (seeing the edge of the lens barrel). Other than look for a different wide-angle adaptor, there's not much to be done. You may notice, however, that the vignetting is more or less pronounced depending on your shooting stop (aperture)--meaning it may intrude more into the shooting area and/or have sharper edges when shooting outside in daylight rather than in low light inside.

The function of different framing (causing the vignette to show up or not) on different displays is called "overscan" such as on your TV, or "underscan" such as in the LCD or computer monitor.

Jeff Donald · July 11th, 2002, 08:56 PM

If you have no filters, or wide angle adapters etc on the front of the lens and you are still vignetting, your lens assembly is out of alignment. I would call Canon and see what they say.

Jeff

July 11th, 2002, 08:08 AM	#1
elusive_kudo Regular Crew Join Date: Apr 2002 Location: Miami Posts: 37	"Ghost" vignetting I have a strange "problem" wih few scenes of my recorded footage and would appreciate any help with it. Some of the footage I took with a widest setting on wide lens which came with my Sony PD 100a do show a small, but visible, what appears to be a vignetting effect in the upper left corner on my LCD screen when playing back. It's also there when I snap a still from those scenes, yet when I play the footage back on regular home TV (I've tried 3 different TV sets) it does not appear at all!!? Does anyone knows what this is exactly and why is it the way it is?

July 11th, 2002, 10:06 AM	#2
Chet Hardin Regular Crew Join Date: Feb 2002 Location: Troy Ny Posts: 60	vignetting Hey -- Most likely that vignetting doesn't go away when you watch it on a tv screen. what goes away is the entire part of the recorded image that the vignetting apears in. i don't know the tech nical terms off the top of me head but what you are watching on the tv does not fully represent the complete aspect ratio of the image you recorded. it sounds like your cameras lcd screen does and that is why you see it on the LCD. I don't understand what you mean "snap a still," do you print it out on your computer? actually, do you have access to a computer with any editing software or a production monitor? if so, then you would see the image with the full ratio the camera recorded. You know, my XL-1's viewfinder doesn't show the full ratio and it is frustrating, especially when you film a girl getting her head chopped off and the mustard botttle that is squirting the blood can be seen in the bottom of the screen, unbeknownst to me until watching "dailies". anyway.

July 11th, 2002, 01:54 PM	#4
Chet Hardin Regular Crew Join Date: Feb 2002 Location: Troy Ny Posts: 60	filters? Do you have any filters attached to this lens?

July 11th, 2002, 05:43 PM	#6
Charles Papert Wrangler Join Date: Jan 2002 Location: Los Angeles, CA Posts: 6,810	When you refer to the "wide lens" that came with your camera, do you mean you are using a screw-on wide angle adaptor? If so, it may be a third-party product that was not designed for the camera, and thus does not offer full coverage of the CCD, thus you are experiencing vignetting (seeing the edge of the lens barrel). Other than look for a different wide-angle adaptor, there's not much to be done. You may notice, however, that the vignetting is more or less pronounced depending on your shooting stop (aperture)--meaning it may intrude more into the shooting area and/or have sharper edges when shooting outside in daylight rather than in low light inside. The function of different framing (causing the vignette to show up or not) on different displays is called "overscan" such as on your TV, or "underscan" such as in the LCD or computer monitor. __________________ Charles Papert www.charlespapert.com

July 11th, 2002, 01:02 PM	#3
elusive_kudo Regular Crew Join Date: Apr 2002 Location: Miami Posts: 37	What I meant when I said that it shows also when I snap a still, meaning when I play back the footage or when I press freeze I can grab a snapshot by pressing "photo" button and record that particular freezed frame as a .jpg on my Sony memory stick. Then when I import that .jpg into my Photoshop, sure enough that ugly thing is visible there. Is there any way to correct this problem in post or am I doomed?

July 11th, 2002, 03:01 PM	#5
elusive_kudo Regular Crew Join Date: Apr 2002 Location: Miami Posts: 37	No, I do not. Just a rectangular hood, but I've tried without it and it still has the same effect so it is inside the lens where it is causing it, not outside. So, when I zoom in it goes away, but I found that I have to zoom in a bit more than just a dash, and that cuts on "wide angle" purpose.

July 11th, 2002, 08:56 PM	#7
Jeff Donald Warden Join Date: Mar 2002 Location: Clearwater, FL Posts: 8,287	If you have no filters, or wide angle adapters etc on the front of the lens and you are still vignetting, your lens assembly is out of alignment. I would call Canon and see what they say. Jeff