Zebra Bars ? How Do They Work at DVinfo.net

Go Back   DV Info Net > Canon EOS / MXF / AVCHD / HDV / DV Camera Systems > Canon HDV and DV Camera Systems > Canon XL and GL Series DV Camcorders > Canon GL Series DV Camcorders

Canon GL Series DV Camcorders
Canon GL2, GL1 and PAL versions XM2, XM1.


Reply
 
Thread Tools Search this Thread
Old February 4th, 2003, 11:23 PM   #1
New Boot
 
Join Date: Feb 2002
Location: Chicago, Illinois, 3 blocks from Wrigley Field
Posts: 14
Zebra Bars ? How Do They Work

I just bought a GL2 and set the Zebra Bars. It looks like the default setting was 90. The Bars or stripes did appear in certain places as I started taping, probably in the areas where there was white. What did the Bars or stripes tell me? I am ignorant. Can someone enlighten me?
Barrie M. Yacher is offline   Reply With Quote
Old February 4th, 2003, 11:43 PM   #2
Obstreperous Rex
 
Join Date: Jan 2001
Location: San Marcos, TX
Posts: 26,900
Images: 513
Hi Barrie,

I think the best short explanation is the one found on page 85 of the GL2 manual: "The zebra pattern is a series of diagonal stripes that appear in the viewfinder to highlight areas of overexposure. Use it as a guide to set the aperture (iris) and shutter speed. You can also select the pattern appearance level from 80, 85, 90, 95, and 100%."

Basically, when the zebra pattern appears, you know you're a bit overexposed, and you can take a number of steps to correct this overexposure: a). make the aperture smaller by increasing the f/stop number on the iris control wheel; b.) increase the shutter speed; c.) decrease the electronic gain, if any. Hope this helps,
__________________
CH

Search DV Info Net | DV Info Net Sponsors | A Decade (+5) of DVi | ...Tuesday is Soylent Green Day!
Chris Hurd is offline   Reply With Quote
Old February 5th, 2003, 05:35 AM   #3
Wrangler
 
Join Date: Sep 2001
Location: Northern VA
Posts: 4,298
The max legal video singal is 100 IRE, anythign above 100 is likely to cause problems in a broadcast signal (e.g., spatter into the sound space). Also, as you get close to 100 (maximum brightness) you start to lose highlight detail - it all washed out. Go a bit above 100 and the camcorder starts to clip the signal. In film terms - that portion of the image is overexposed. Bit haveing part of the image overexposed may not be all bad - if it is a part you are not especially interested in - such as a bright light source refection from a metal surface or the view from a window in an interior shot.

The zebra provides a visual indication/warning of this in the viewfinder, and the operator can adjust exposure accordingly to obtain the desire effect. Allowing diffent settings for the zebra threshold allows the shooter to match the camcorde to his/her preference.

One way to use zebra is set it to 95 and then shoot with the brightest highlight in which you want image detail on the verge of showing zebra.
Don Palomaki is offline   Reply With Quote
Old February 5th, 2003, 11:03 PM   #4
Retired DV Info Net Almunus
 
Join Date: Dec 2001
Location: Chicago, IL
Posts: 6,943
Hey Barrie,

Good to see another fellow Chicagoan on DVInfo! I grew up in your neighborhood.

Welcome to the DVInfo community!
__________________
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
Ken Tanaka is offline   Reply With Quote
Old February 5th, 2003, 11:06 PM   #5
New Boot
 
Join Date: Feb 2002
Location: Chicago, Illinois, 3 blocks from Wrigley Field
Posts: 14
I want to thank Chris Hurd and Don Palomaki for responding to my question about zebra bars. I will reread your answers 100 times.
Barrie M. Yacher is offline   Reply With Quote
Old February 5th, 2003, 11:10 PM   #6
Wrangler
 
Join Date: Feb 2002
Location: Cleveland, Ohio
Posts: 1,929
Does anyone know what the spatial resolution of the zebra patterns are? How many adjacent pixels have to be supraliminal (above the exposure threshold) for them to be zebra'd?

(And is the zebra resolution different for the XL1S?)
__________________
All the best,
Robert K S

Search DVinfo.net for quick answers | The best in the business: DVinfo.net sponsors
Robert Knecht Schmidt is offline   Reply With Quote
Old February 5th, 2003, 11:22 PM   #7
Warden
 
Join Date: Mar 2002
Location: Clearwater, FL
Posts: 8,267
The last figure I seem to recall was a 90+% accuracy. This was for a pro B & W view finder, maybe 8 to 10 years ago. Not really extremely accurate. Thats why waveform monitors are used when you have to know about your exposure. I try to see if I have any more information on it or how it is measured.

I would think a LCD screen would have much less accuracy than a CRT also. I think that's why we are all erring on the side of caution. You can always bump your levels a little in post. but once your highlights are gone, it's all over.
__________________
Jeff Donald
Carpe Diem




Search DVinfo.net for quick answers | Where to Buy? From the best in the business: DVinfo.net sponsors
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 > Canon EOS / MXF / AVCHD / HDV / DV Camera Systems > Canon HDV and DV Camera Systems > Canon XL and GL Series DV Camcorders > Canon GL Series DV Camcorders

Thread Tools Search this Thread
Search this Thread:

Advanced Search

 



Google
 

All times are GMT -6. The time now is 08:22 PM.


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