Am I losing out using the ND filter

David Koo · July 31st, 2007, 08:57 PM

What I don't understand is this...

Why can't we just adjust the shutter speed instead of using an ND filter?

Does a faster shutter speed degrade the video?

In still photography with a digital SLR, all I have to do to get a shallow DOF is to open up the aperture as wide a possible and then use a faster shutter speed to compensate...

thanks...

Scott Becker · July 31st, 2007, 10:44 PM

Quote:

Originally Posted by Eric Weiss

Yes. In ample light situations, using the ND's will provide very sharp shots with even exposure and a greater depth of focus.

You will not lose quality by adding ND's provided that your exposure is what you intend it to be.

Trust your VF over the LCD and don't rely 100% on the meter. I find over exposing my shots by a notch or two gives cleaner shots.

So is ND best used with a brighter exposure?

Mark Rook · August 1st, 2007, 01:54 AM

So if depth of field isn't an issue, what aperture setting would produce a sharper picture.

Thanks again, its beeen an interesting read.

Mark

Bill Pryor · August 1st, 2007, 10:51 AM

David, the comparison of a video to a still camera doesn't hold up in this area. If you use a slower or faster shutter speed, you are going to get an effect. With a slower speed, it will blur and strobe. Faster shutter speeds can affect objects that turn. For example, if you have a fan available, aim the camera at the fan and start adjusting the shutter speed faster. After a time you will see the blades begin to slow, even stop and appear to move backwards. You can, however, use a little faster speed if you want. Some peole think shooting at, say, a 1/100 or 1/125 is better if you are going to do slow motion in post. I've tried that and with interlaced video it may make just a little difference, but not much. With 24P I'm not sure what it would do.

Bill Busby · August 1st, 2007, 11:18 AM

Quote:

Originally Posted by Eric Weiss

the lcd is fine to monitor and focus, but i find the vf to be more accurate with color temp and exposure.

My A1's VF has a very slight greenish hue, as does a friends A1 as well. Anyone else's have this?

Bill

Mark Rook · August 1st, 2007, 02:50 PM

I went out this evening to shoot some video of the large wind turbines we have around here. Using the 1/32 ND filter gave sharper results and more fluid motion when the blades were turning, I guess this is because of the slower shutter speed. As far as a green tint, I haven't notice this.

Well I'm pleased I asked this question now.

Mark.

Steven Taylor · August 1st, 2007, 04:27 PM

Quote:

Originally Posted by Bill Pryor

David, the comparison of a video to a still camera doesn't hold up in this area. If you use a slower or faster shutter speed, you are going to get an effect. With a slower speed, it will blur and strobe. Faster shutter speeds can affect objects that turn. For example, if you have a fan available, aim the camera at the fan and start adjusting the shutter speed faster. After a time you will see the blades begin to slow, even stop and appear to move backwards. You can, however, use a little faster speed if you want. Some peole think shooting at, say, a 1/100 or 1/125 is better if you are going to do slow motion in post. I've tried that and with interlaced video it may make just a little difference, but not much. With 24P I'm not sure what it would do.

So are there any reasons to change shutter speed based on the motion of what you are filming rather than exposure/light level issues?

Bill Pryor · August 1st, 2007, 05:16 PM

Basically no, if you want normal looking video. The purpose of the shutter in motion picture filming is not to adjust exposure time but to create individual frames, basically. That's not really technically accurate but it's the idea. I'm not an engineer so I don't know how it really works, but the shutter "closes" between every frame (does it close and open between every field in interlaced video? I dunno.) In a film camera you have a real shutter that opens and closed; in video it's electronic and I don't know what really happens.

You can often change shutter speed (if you have a camera without clear scan functions) and cause a monitor roll or projector roll to partially go away if you're trying to shoot an old style TV or a movie screen. Different shutter speeds will give different effects. Using a very slow shutter speed can give you a cool effect--try a 1/8 shutter with the camera locked down and people walking by. They'll blur and strobe, but if there's, say, a building in the background, it will stay normal and sharp. If you pan with the people, they'll stay sharp and the building in the background will blur. It's a nice effect for some things. Try zooming in and out with the same setting; you get some cool weirdness there too. You'll have to stop way down and/or use an additional ND filter, most likely.

You can get by with using a slower speed to gain exposure in some circumstances. For instance, a friend of mine and I shot a wedding for a client one time (we normally don't do weddings), and I was using a JVC GY500. He had his Canon XL1, which wanted a lot more light than the JVC. His angle was up in the balcony looking down at the procession coming in. Nobody moves very fast in that situation, so in order to get enough light and not use a high gain, he shot at a 1/30 (standard is 1/60 for NTSC interlace). Since nobody was moving very fast, and since the motion generally was away from the camera rather than laterally across the frame, it all looked normal. But if somebody went running across the frame, he would have strobed.

You can also go slightly faster with your shutter for the opposite, but only a little bit. You go too fast and you get very weird effects, as I mentioned in an earlier post.

So, basically you should use the standard shutter speeds almost all the time--1/48 for shooting 24fps and 1/60 for 60i--unless you're after a certain effect, or in certain limited situations where you can get by with it to control exposure to a limited degree. Most camcorders will show a bit of a quality drop at different shutter speeds. I haven't done anything with the Canon yet, but in shooting slow shutter speeds with a DSR250, the image gets soft and grainy, but you can get by with it because it's an effect and nobody will notice.

Richard Zlamany · August 1st, 2007, 05:40 PM

The ND filters make a better picture because they allow the iris to be opened half way or so at the sweet spot. That is where the picture looks the best. Sometimes, because I want the f stop at 4.8 and I have 2 ND filters on, I'll use a shutter of 180 to help reduce the afternoon beach brightness and still have 4.8.

David Koo · August 1st, 2007, 08:42 PM

Thanks Bill for the info...

That was very helpful...

I'll full around with the shutter speed on my camera to see how it effect the picture...

dave

Scott Becker · August 1st, 2007, 09:26 PM

So it's better for the shutter speed to match the frame rate - is that right?

Mark Rook · August 2nd, 2007, 02:16 AM

I mainly use 1080/50i, and have noticed that using a 1/120th shutter speed does give nice results. I film a lot of air shows and have noticed if you run a fast shutter speed you end up having the props on planes look like their standing still. The slower shutter helps keep everything look more natural.

Mark

Joe Rizzo-Naudi · August 2nd, 2007, 05:29 AM

Just for reference, here's a still frame from a bit of experimentation footage. Mid way through a pan, 1080/50i with the shutter speed at about 1/1000. Pretty extreme, but you get a very definate ghosting in the image. In still shots at this shutter speed, the footage looks very jumpy and neurotic. Could be useful if you want this effect :)

http://pic20.picturetrail.com/VOL91/.../250701321.jpg

Scott Becker · August 2nd, 2007, 01:37 PM

I tried using both settings with the ND. On a bright hazy day, like today, it really adds more blue to the sky, and pulls out other colors in general.

July 31st, 2007, 08:57 PM	#16
David Koo Regular Crew Join Date: Oct 2006 Location: Cincinnati, OH Posts: 51	What I don't understand is this... Why can't we just adjust the shutter speed instead of using an ND filter? Does a faster shutter speed degrade the video? In still photography with a digital SLR, all I have to do to get a shallow DOF is to open up the aperture as wide a possible and then use a faster shutter speed to compensate... thanks...

August 1st, 2007, 01:54 AM	#18
Mark Rook Regular Crew Join Date: May 2007 Location: Aberystwyth, Wales, UK Posts: 91	So if depth of field isn't an issue, what aperture setting would produce a sharper picture. Thanks again, its beeen an interesting read. Mark

August 1st, 2007, 10:51 AM	#19
Bill Pryor Contributor Join Date: Jan 2003 Location: Kansas City, MO Posts: 4,449	David, the comparison of a video to a still camera doesn't hold up in this area. If you use a slower or faster shutter speed, you are going to get an effect. With a slower speed, it will blur and strobe. Faster shutter speeds can affect objects that turn. For example, if you have a fan available, aim the camera at the fan and start adjusting the shutter speed faster. After a time you will see the blades begin to slow, even stop and appear to move backwards. You can, however, use a little faster speed if you want. Some peole think shooting at, say, a 1/100 or 1/125 is better if you are going to do slow motion in post. I've tried that and with interlaced video it may make just a little difference, but not much. With 24P I'm not sure what it would do.

August 1st, 2007, 02:50 PM	#21
Mark Rook Regular Crew Join Date: May 2007 Location: Aberystwyth, Wales, UK Posts: 91	I went out this evening to shoot some video of the large wind turbines we have around here. Using the 1/32 ND filter gave sharper results and more fluid motion when the blades were turning, I guess this is because of the slower shutter speed. As far as a green tint, I haven't notice this. Well I'm pleased I asked this question now. Mark.

August 1st, 2007, 05:16 PM	#23
Bill Pryor Contributor Join Date: Jan 2003 Location: Kansas City, MO Posts: 4,449	Basically no, if you want normal looking video. The purpose of the shutter in motion picture filming is not to adjust exposure time but to create individual frames, basically. That's not really technically accurate but it's the idea. I'm not an engineer so I don't know how it really works, but the shutter "closes" between every frame (does it close and open between every field in interlaced video? I dunno.) In a film camera you have a real shutter that opens and closed; in video it's electronic and I don't know what really happens. You can often change shutter speed (if you have a camera without clear scan functions) and cause a monitor roll or projector roll to partially go away if you're trying to shoot an old style TV or a movie screen. Different shutter speeds will give different effects. Using a very slow shutter speed can give you a cool effect--try a 1/8 shutter with the camera locked down and people walking by. They'll blur and strobe, but if there's, say, a building in the background, it will stay normal and sharp. If you pan with the people, they'll stay sharp and the building in the background will blur. It's a nice effect for some things. Try zooming in and out with the same setting; you get some cool weirdness there too. You'll have to stop way down and/or use an additional ND filter, most likely. You can get by with using a slower speed to gain exposure in some circumstances. For instance, a friend of mine and I shot a wedding for a client one time (we normally don't do weddings), and I was using a JVC GY500. He had his Canon XL1, which wanted a lot more light than the JVC. His angle was up in the balcony looking down at the procession coming in. Nobody moves very fast in that situation, so in order to get enough light and not use a high gain, he shot at a 1/30 (standard is 1/60 for NTSC interlace). Since nobody was moving very fast, and since the motion generally was away from the camera rather than laterally across the frame, it all looked normal. But if somebody went running across the frame, he would have strobed. You can also go slightly faster with your shutter for the opposite, but only a little bit. You go too fast and you get very weird effects, as I mentioned in an earlier post. So, basically you should use the standard shutter speeds almost all the time--1/48 for shooting 24fps and 1/60 for 60i--unless you're after a certain effect, or in certain limited situations where you can get by with it to control exposure to a limited degree. Most camcorders will show a bit of a quality drop at different shutter speeds. I haven't done anything with the Canon yet, but in shooting slow shutter speeds with a DSR250, the image gets soft and grainy, but you can get by with it because it's an effect and nobody will notice.

August 1st, 2007, 05:40 PM	#24
Richard Zlamany Major Player Join Date: Jun 2005 Location: Hamden CT Posts: 470	The ND filters make a better picture because they allow the iris to be opened half way or so at the sweet spot. That is where the picture looks the best. Sometimes, because I want the f stop at 4.8 and I have 2 ND filters on, I'll use a shutter of 180 to help reduce the afternoon beach brightness and still have 4.8.

August 1st, 2007, 08:42 PM	#25
David Koo Regular Crew Join Date: Oct 2006 Location: Cincinnati, OH Posts: 51	Thanks Bill for the info... That was very helpful... I'll full around with the shutter speed on my camera to see how it effect the picture... dave

August 1st, 2007, 09:26 PM	#26
Scott Becker New Boot Join Date: Jul 2007 Location: Los Angeles Posts: 16	So it's better for the shutter speed to match the frame rate - is that right?

August 2nd, 2007, 02:16 AM	#27
Mark Rook Regular Crew Join Date: May 2007 Location: Aberystwyth, Wales, UK Posts: 91	I mainly use 1080/50i, and have noticed that using a 1/120th shutter speed does give nice results. I film a lot of air shows and have noticed if you run a fast shutter speed you end up having the props on planes look like their standing still. The slower shutter helps keep everything look more natural. Mark

August 2nd, 2007, 05:29 AM	#28
Joe Rizzo-Naudi Regular Crew Join Date: May 2007 Location: London, UK Posts: 32	Just for reference, here's a still frame from a bit of experimentation footage. Mid way through a pan, 1080/50i with the shutter speed at about 1/1000. Pretty extreme, but you get a very definate ghosting in the image. In still shots at this shutter speed, the footage looks very jumpy and neurotic. Could be useful if you want this effect :) http://pic20.picturetrail.com/VOL91/.../250701321.jpg

August 2nd, 2007, 01:37 PM	#29
Scott Becker New Boot Join Date: Jul 2007 Location: Los Angeles Posts: 16	I tried using both settings with the ND. On a bright hazy day, like today, it really adds more blue to the sky, and pulls out other colors in general.