How do I get the right exposure ?

Rick Spilman · April 28th, 2003, 06:37 PM

"I found it hard to eliminate the zebra pattern without under exposing the part in shadow."

I think the one clear problem you have is getting use to the zebra pattern. In a nutshell, it is fine to slightly overexpose the parts of the shot that do not matter to you as long as you get the portion of the shot that you need.

As Mike pointed out at a 70% zebra there should be some striping on faces. A light colored shirt, flowers or a sunlit wall will show zebra stripes. Zebra stripes aren't bad.

You may want to turn off the zebra stripes for a while. Shoot what looks right then turn the stripes back on and see what is striping and what isn't. Then play back the footage preferably through a monitor but even the LCD will work if you aren't in the sun. Video gives you instant feed back. See what looks good then shoot some more until you get a clear idea of how to make the zebra stripes work for you.

Dennis Hull · April 28th, 2003, 06:58 PM

Wayne, I agree with you based on most of what I have read about ND filters and what they are supposed to do (I have mostly reading at this stage with little practical experience) , but page 33 of March 2003 "Camcorder and Computer Video" magazine article on use of filters says "The ND filter adds more intensity and deeper colors to images that are washed out from excessive light present in the scene." I thought this might help account for why I saw much better results from VX2000 in high contrast (sun/shadow) scene vs competitive camera ( the VX2000 had ND filter switched in and I don't think the competitive camera had its one ND filter switched in). On the other hand, might be semantics of magazine article.

Jeff Donald · April 28th, 2003, 07:11 PM

A good neutral density filter is just that, neutral. It neither adds or subtracts color to any scene (more the job of a polarizer). The washed out look would be more the result of over exposure. By using a ND filter, the scene is prevented from over exposing. This results in improved color and better contrast.

Dennis Hull · April 28th, 2003, 07:32 PM

Wayne and Jeff, Right you are and it all now begins to make sense--neutral but helps with exposure resulting in better colors and contrast without washouts. Thanks for patience in explaining this.

Wayne Orr · April 28th, 2003, 08:45 PM

You people are so lucky that my series has wrapped and I have the time to "pig out" on the web and pass along these pearls of wisdom. Here are the latest.

I second Bryan's endorsement of the linear polarizer. The circular will work fine, but you will pay extra for it. BTW, remember when using a polarizer, if you pan 45 degrees you may totally eliminate the effect of the polarizer, which will result in overexposure if you do not compensate by changing the iris. The best thing to do is preview your planned shot just by eyeballing through the filter. You will be able to see the change, and know that you will have to compensate.

Rick's response to the original post from Robb is on the mark, but there is a caveat here about using lcd's to check exposure. My experience is that the little screens tend to make everything look good, and that coupled with the different results from a slightly different viewing angle make them unreliable for real critical judgment, IMHO. Another thing that is buggy about the zebras, is they will show up in areas beyond 70%, and this can be decieving. In betacams and other professional Sony cameras, the 70% bars appear only in the area of 70 to 80%. Anything higher, and they go away. But on my PD150 they first appear at 70% and stay on ad infinitum. Let's say there is a face we are shooting, and a 70% highlight should appear on the cheek bones, nose and forehead at f/4. That would be proper exposure. However, when we first set the exposure, if we start from wide open, and begin to iris down, we see the zebra first appear at f/2/4, possibly leading us to believe that is the correct exposure. What you may be seeing coming from wide open, is the high end of the range. So, what I suggest is, look for the zebras coming from a closed iris setting, such as f/11 or f/8. Then you will be increasing the exposure, coming from 10% to 20% etc, till you come to 70%, where you first see the zebras. I hope this makes sense, because it is pretty important, and you won't find this in any of the literature.

Please read my response to Robb about learning to "squint." I promise one day you will thank me for this advice, along with the DP who passed it on to me. Do I sound like your father?

"The ND filter adds more intensity and deeper colors to images that are washed out from excessive light present in the scene." This is about what I would expect from something called "Camcorder and Computer Video," Dennis. OK, everybody, what's the purpose of a magazine? Altogether now: "To sell advertising!!!" Thank you. The best way to compare two cameras is to look at their output on the same scene through a professional monitor, or at least a quality television. Certainly do not depend on the lcd's.

Excuse me now. I have to return to the "help wanted" section of the Times.

Jeff Donald · April 29th, 2003, 11:33 AM

The Saran Wrap question was off topic and moved to here.

April 28th, 2003, 06:58 PM	#17
Dennis Hull Regular Crew Join Date: Sep 2002 Location: St. Paul, MN USA Posts: 151	Neutral on Neutral Density Wayne, I agree with you based on most of what I have read about ND filters and what they are supposed to do (I have mostly reading at this stage with little practical experience) , but page 33 of March 2003 "Camcorder and Computer Video" magazine article on use of filters says "The ND filter adds more intensity and deeper colors to images that are washed out from excessive light present in the scene." I thought this might help account for why I saw much better results from VX2000 in high contrast (sun/shadow) scene vs competitive camera ( the VX2000 had ND filter switched in and I don't think the competitive camera had its one ND filter switched in). On the other hand, might be semantics of magazine article.

April 28th, 2003, 07:11 PM	#18
Jeff Donald Warden Join Date: Mar 2002 Location: Clearwater, FL Posts: 8,287	A good neutral density filter is just that, neutral. It neither adds or subtracts color to any scene (more the job of a polarizer). The washed out look would be more the result of over exposure. By using a ND filter, the scene is prevented from over exposing. This results in improved color and better contrast. __________________ Jeff Donald Carpe Diem Search DVinfo.net for quick answers \| Where to Buy? From the best in the business: DVinfo.net sponsors

April 28th, 2003, 07:32 PM	#19
Dennis Hull Regular Crew Join Date: Sep 2002 Location: St. Paul, MN USA Posts: 151	Convinced Wayne and Jeff, Right you are and it all now begins to make sense--neutral but helps with exposure resulting in better colors and contrast without washouts. Thanks for patience in explaining this.

April 28th, 2003, 08:45 PM	#20
Wayne Orr Major Player Join Date: Dec 2002 Location: Northridge Ca Posts: 734	More pearls You people are so lucky that my series has wrapped and I have the time to "pig out" on the web and pass along these pearls of wisdom. Here are the latest. I second Bryan's endorsement of the linear polarizer. The circular will work fine, but you will pay extra for it. BTW, remember when using a polarizer, if you pan 45 degrees you may totally eliminate the effect of the polarizer, which will result in overexposure if you do not compensate by changing the iris. The best thing to do is preview your planned shot just by eyeballing through the filter. You will be able to see the change, and know that you will have to compensate. Rick's response to the original post from Robb is on the mark, but there is a caveat here about using lcd's to check exposure. My experience is that the little screens tend to make everything look good, and that coupled with the different results from a slightly different viewing angle make them unreliable for real critical judgment, IMHO. Another thing that is buggy about the zebras, is they will show up in areas beyond 70%, and this can be decieving. In betacams and other professional Sony cameras, the 70% bars appear only in the area of 70 to 80%. Anything higher, and they go away. But on my PD150 they first appear at 70% and stay on ad infinitum. Let's say there is a face we are shooting, and a 70% highlight should appear on the cheek bones, nose and forehead at f/4. That would be proper exposure. However, when we first set the exposure, if we start from wide open, and begin to iris down, we see the zebra first appear at f/2/4, possibly leading us to believe that is the correct exposure. What you may be seeing coming from wide open, is the high end of the range. So, what I suggest is, look for the zebras coming from a closed iris setting, such as f/11 or f/8. Then you will be increasing the exposure, coming from 10% to 20% etc, till you come to 70%, where you first see the zebras. I hope this makes sense, because it is pretty important, and you won't find this in any of the literature. Please read my response to Robb about learning to "squint." I promise one day you will thank me for this advice, along with the DP who passed it on to me. Do I sound like your father? "The ND filter adds more intensity and deeper colors to images that are washed out from excessive light present in the scene." This is about what I would expect from something called "Camcorder and Computer Video," Dennis. OK, everybody, what's the purpose of a magazine? Altogether now: "To sell advertising!!!" Thank you. The best way to compare two cameras is to look at their output on the same scene through a professional monitor, or at least a quality television. Certainly do not depend on the lcd's. Excuse me now. I have to return to the "help wanted" section of the Times. __________________ Wayne If it was easy, they'd get a relative to do it.

April 29th, 2003, 11:33 AM	#21
Jeff Donald Warden Join Date: Mar 2002 Location: Clearwater, FL Posts: 8,287	The Saran Wrap question was off topic and moved to here. __________________ Jeff Donald Carpe Diem Search DVinfo.net for quick answers \| Where to Buy? From the best in the business: DVinfo.net sponsors

April 28th, 2003, 06:37 PM	#16
Rick Spilman Major Player Join Date: Dec 2002 Location: Jersey City, NJ Posts: 366	"I found it hard to eliminate the zebra pattern without under exposing the part in shadow." I think the one clear problem you have is getting use to the zebra pattern. In a nutshell, it is fine to slightly overexpose the parts of the shot that do not matter to you as long as you get the portion of the shot that you need. As Mike pointed out at a 70% zebra there should be some striping on faces. A light colored shirt, flowers or a sunlit wall will show zebra stripes. Zebra stripes aren't bad. You may want to turn off the zebra stripes for a while. Shoot what looks right then turn the stripes back on and see what is striping and what isn't. Then play back the footage preferably through a monitor but even the LCD will work if you aren't in the sun. Video gives you instant feed back. See what looks good then shoot some more until you get a clear idea of how to make the zebra stripes work for you.