"Ghost" vignetting at DVinfo.net

Go Back   DV Info Net > The Tools of DV and HD Production > Open DV Discussion

Open DV Discussion
For topics which don't fit into any of the other categories.


Reply
 
Thread Tools Search this Thread
Old July 11th, 2002, 09:08 AM   #1
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?
elusive_kudo is offline   Reply With Quote
Old July 11th, 2002, 11:06 AM   #2
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.
Chet Hardin is offline   Reply With Quote
Old July 11th, 2002, 02:02 PM   #3
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?
elusive_kudo is offline   Reply With Quote
Old July 11th, 2002, 02:54 PM   #4
Regular Crew
 
Join Date: Feb 2002
Location: Troy Ny
Posts: 60
filters?

Do you have any filters attached to this lens?
Chet Hardin is offline   Reply With Quote
Old July 11th, 2002, 04:01 PM   #5
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.
elusive_kudo is offline   Reply With Quote
Old July 11th, 2002, 06:43 PM   #6
Wrangler
 
Join Date: Jan 2002
Location: Los Angeles, CA
Posts: 6,781
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
Charles Papert is offline   Reply With Quote
Old July 11th, 2002, 09:56 PM   #7
Warden
 
Join Date: Mar 2002
Location: Clearwater, FL
Posts: 8,267
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
Jeff Donald is offline   Reply
Reply

DV Info Net refers all where-to-buy and where-to-rent questions exclusively to these trusted full line dealers and rental houses...

Professional Video
(800) 833-4801
Portland, OR

B&H Photo Video
(866) 521-7381
New York, NY

Z.G.C.
(973) 335-4460
Mountain Lakes, NJ

Abel Cine Tech
(888) 700-4416
N.Y. NY & L.A. CA

Precision Camera
(800) 677-1023
Austin, TX

DV Info Net also encourages you to support local businesses and buy from an authorized dealer in your neighborhood.
  You are here: DV Info Net > The Tools of DV and HD Production > Open DV Discussion

Thread Tools Search this Thread
Search this Thread:

Advanced Search

 



Google
 

All times are GMT -6. The time now is 07:09 AM.


DV Info Net -- Real Names, Real People, Real Info!
1998-2017 The Digital Video Information Network