How to set Zebras

Allan Black · September 14th, 2008, 04:54 PM

Thanks Tom, very interesting, I'd like to know more too.

Cheers.

Tom Hardwick · September 15th, 2008, 01:26 AM

I have no links Allan and Jo - it's just what I've taught myself. And it's so easy to experimentally verify. Camera on tripod, pointing out into the garden. Connect to a big, well set up TV and use this in combination with the camera's v'finders. Set zebras on.

I use 100% for no good reason other than I've grown up with them at this setting and know what they mean and what they're telling me. I take it that zebras starting to appear will mean burn-out to pure white on the final DVD (not necessarily the TV monitor of your timeline, note).

Record footage as you open the iris blades, talking to those mics all the time - describe accurately when the zebras appear, where they occur and when they leave the scene. Replay this tape and take note.

Once you've done this you'll know how you camera behaves. And it's this that makes me wary of people who hire a camera for an event, because all cameras have their foibles.

tom.

Allan Black · September 15th, 2008, 02:00 AM

Tom 'open the blades' you say there. Post 14 was intriguing in that you mentioned 'most cameras have a hysteresis loop' I assume this applies to vid cams.

And you'd select one or the other, either open or close the iris for a particular cam to run your test and stay with it?

Cheers.

Tom Hardwick · September 15th, 2008, 02:15 AM

Yes, I've only ever seen this zebra this hysteresis loop on video cameras I've known. Your mileage may vary. And yes again - always approach your zebras from the same way and you'll always be told the same info.

Jo Potts · September 15th, 2008, 04:23 AM

I understand your method of testing - it makes sense to know at which point you want your zebras to appear. I personally use 75, but that's just what i've always been used to.

I was more interested about what you were saying about the hysteresis loop - and how zebras can appear and then dissappear again. I've never seen this, but would be interested to hear more.

Tom Hardwick · September 15th, 2008, 04:47 AM

As I say Jo - so easy to test for yourself. What camera do you have? If it's a Canon it may not be so - I haven't checked, but my Sonys have always shown this loop. Even at the 100% setting I can see the zebras come in at f/8 on a highlight and leave by f/4. But you say you've not had problems so fine - carry on shooting.

Jo Potts · September 15th, 2008, 04:12 PM

I've got an XH-A1 and before that used and XL2. I'll have to have a play see if I can find anything!

September 15th, 2008, 04:23 AM	#20
Jo Potts Regular Crew Join Date: Apr 2008 Location: Cambridge, UK Posts: 40	I understand your method of testing - it makes sense to know at which point you want your zebras to appear. I personally use 75, but that's just what i've always been used to. I was more interested about what you were saying about the hysteresis loop - and how zebras can appear and then dissappear again. I've never seen this, but would be interested to hear more. __________________ MBP 15" 2.6Ghz, 4GB RAM. 2TB storage. FCS2. Canon XH-A1. www.jpcreativemedia.com vimeo.com/user449069

September 15th, 2008, 04:12 PM	#22
Jo Potts Regular Crew Join Date: Apr 2008 Location: Cambridge, UK Posts: 40	I've got an XH-A1 and before that used and XL2. I'll have to have a play see if I can find anything! __________________ MBP 15" 2.6Ghz, 4GB RAM. 2TB storage. FCS2. Canon XH-A1. www.jpcreativemedia.com vimeo.com/user449069

September 14th, 2008, 04:54 PM	#16
Allan Black Inner Circle Join Date: Sep 2006 Location: Sydney. Posts: 2,887	Thanks Tom, very interesting, I'd like to know more too. Cheers.

September 15th, 2008, 01:26 AM	#17
Tom Hardwick Inner Circle Join Date: Mar 2003 Location: Billericay, England UK Posts: 4,711	I have no links Allan and Jo - it's just what I've taught myself. And it's so easy to experimentally verify. Camera on tripod, pointing out into the garden. Connect to a big, well set up TV and use this in combination with the camera's v'finders. Set zebras on. I use 100% for no good reason other than I've grown up with them at this setting and know what they mean and what they're telling me. I take it that zebras starting to appear will mean burn-out to pure white on the final DVD (not necessarily the TV monitor of your timeline, note). Record footage as you open the iris blades, talking to those mics all the time - describe accurately when the zebras appear, where they occur and when they leave the scene. Replay this tape and take note. Once you've done this you'll know how you camera behaves. And it's this that makes me wary of people who hire a camera for an event, because all cameras have their foibles. tom.

September 15th, 2008, 02:00 AM	#18
Allan Black Inner Circle Join Date: Sep 2006 Location: Sydney. Posts: 2,887	Tom 'open the blades' you say there. Post 14 was intriguing in that you mentioned 'most cameras have a hysteresis loop' I assume this applies to vid cams. And you'd select one or the other, either open or close the iris for a particular cam to run your test and stay with it? Cheers.

September 15th, 2008, 02:15 AM	#19
Tom Hardwick Inner Circle Join Date: Mar 2003 Location: Billericay, England UK Posts: 4,711	Yes, I've only ever seen this zebra this hysteresis loop on video cameras I've known. Your mileage may vary. And yes again - always approach your zebras from the same way and you'll always be told the same info.

September 15th, 2008, 04:47 AM	#21
Tom Hardwick Inner Circle Join Date: Mar 2003 Location: Billericay, England UK Posts: 4,711	As I say Jo - so easy to test for yourself. What camera do you have? If it's a Canon it may not be so - I haven't checked, but my Sonys have always shown this loop. Even at the 100% setting I can see the zebras come in at f/8 on a highlight and leave by f/4. But you say you've not had problems so fine - carry on shooting.