jando_garcia
New member
When shooting with the dvx and you are lighting a scene, what ASA would you set your meter to in order to properly calculate light readings? Any info or links would be greatly appreciated.
ASA setting meter readings???
- Thread starter jando_garcia
- Start date
10s
Veteran
Re: ASA setting meter readings???
320 ASA, is the typical chip sensitivity for many video cams. I'm told it's twice this, 640, for this DVX camera.
On the other hand American Cinematography Magazine tested the camera, April 2002 issue up against ARRI 35mm & 16mm using Kodaks new Vision2 5218 & 7218 stock. They consider the DVX camera to have an effective ASA of around 320, but they suggested to underexpose by a 1/2 stop. They loved the DVX, couldn't believe how sharp the Lecia lens was.
Set your meter to 320 or 640? ASA, 24 or 30 fps, and shutter is twice your frame rate, for 24 fps it should be 48 or it can default to 50 that's acceptable, & 60 shutter for 30 fps.
I meter with my Spectra IV Pro incident meter here & there & also use the on-board DVX auto exposure setting, zebras for quazi-spot metering. They end up being different ???. it does give me good ratios!
I trust the Spectra, it's a standard for film...or it use to be...many cinematographers eye ball it after a while....could be dangerous!
Many like to stop down a few notches...I'm still out on that one.
Meters will give consistent exposure. That's nice when post rolls around and you need to match cuts.
Don't trust that LCD. What ever you do use one zebra at 98 or 100, (there's some room for slightly going over 100, but not much so don't push it or it's scrap) & setup on the camera, I think it should be 7.5 for monitoring how NTSC looks.
320 ASA, is the typical chip sensitivity for many video cams. I'm told it's twice this, 640, for this DVX camera.
On the other hand American Cinematography Magazine tested the camera, April 2002 issue up against ARRI 35mm & 16mm using Kodaks new Vision2 5218 & 7218 stock. They consider the DVX camera to have an effective ASA of around 320, but they suggested to underexpose by a 1/2 stop. They loved the DVX, couldn't believe how sharp the Lecia lens was.
Set your meter to 320 or 640? ASA, 24 or 30 fps, and shutter is twice your frame rate, for 24 fps it should be 48 or it can default to 50 that's acceptable, & 60 shutter for 30 fps.
I meter with my Spectra IV Pro incident meter here & there & also use the on-board DVX auto exposure setting, zebras for quazi-spot metering. They end up being different ???. it does give me good ratios!
I trust the Spectra, it's a standard for film...or it use to be...many cinematographers eye ball it after a while....could be dangerous!
Many like to stop down a few notches...I'm still out on that one. Meters will give consistent exposure. That's nice when post rolls around and you need to match cuts.
Don't trust that LCD. What ever you do use one zebra at 98 or 100, (there's some room for slightly going over 100, but not much so don't push it or it's scrap) & setup on the camera, I think it should be 7.5 for monitoring how NTSC looks.
Barry_Green
Moderator
Re: ASA setting meter readings???
There's a long thread here, search in the archives. Basically a meter will not give you an overall accurate reading; the camera responds at different sensitivities depending on the overall light level. For most of the exposure curve it responds at 640 ISO, but in lower light levels it responds at 400 and at brighter levels it will respond at 800 to 1000 ISO, depending on the gamma curve selected.
There's a long thread here, search in the archives. Basically a meter will not give you an overall accurate reading; the camera responds at different sensitivities depending on the overall light level. For most of the exposure curve it responds at 640 ISO, but in lower light levels it responds at 400 and at brighter levels it will respond at 800 to 1000 ISO, depending on the gamma curve selected.
blazingoat
Carbonite Member
Re: ASA setting meter readings???
why does the setup need to be a 7.5? Isn't 0 better? It seems to give you more crushed blacks and better contrast. (A more pleasing image to my eye). Please explain.
why does the setup need to be a 7.5? Isn't 0 better? It seems to give you more crushed blacks and better contrast. (A more pleasing image to my eye). Please explain.
Re: ASA setting meter readings???
The setup should aleays be set at 0, NOT 7.5 IRE. For DVD or Web distribution, setup is irrelevant. DVD players will automatically add a 7.5 IRE setup for NTSC analog output. In some case you can change this to 0 IRE for component output in a more sophisticated setup. For broadcast, any setup would be added later as necessary, using a proc amp. A setup of 7.5 IRE is an *analog NTSC* output standard. It should have never been made an option in the DVX100, because it was not implemented correctly, and serves no purpose--other than potentially mucking up your DV material and confusing the hell out of anyone that has to deal with your footage.
The setup should aleays be set at 0, NOT 7.5 IRE. For DVD or Web distribution, setup is irrelevant. DVD players will automatically add a 7.5 IRE setup for NTSC analog output. In some case you can change this to 0 IRE for component output in a more sophisticated setup. For broadcast, any setup would be added later as necessary, using a proc amp. A setup of 7.5 IRE is an *analog NTSC* output standard. It should have never been made an option in the DVX100, because it was not implemented correctly, and serves no purpose--other than potentially mucking up your DV material and confusing the hell out of anyone that has to deal with your footage.
Barry_Green
Moderator
Re: ASA setting meter readings???
Barry_S speaks the truth for the vast majority of circumstances. However there is one place that I can think of where using 7.5 might be appropriate, and that would be if you were using your DVX as a "live feed" for an analog recording deck. If you were using a DVX and had it connected by s-video to an analog mixer or analog deck, then using the 7.5 might make sense.
For digital recording (onto DV tape, through firewire, onto a FireStore, etc) you *always* want the setup option set to 0.
Barry_S speaks the truth for the vast majority of circumstances. However there is one place that I can think of where using 7.5 might be appropriate, and that would be if you were using your DVX as a "live feed" for an analog recording deck. If you were using a DVX and had it connected by s-video to an analog mixer or analog deck, then using the 7.5 might make sense.
For digital recording (onto DV tape, through firewire, onto a FireStore, etc) you *always* want the setup option set to 0.
blazingoat
Carbonite Member
Re: ASA setting meter readings???
That's what i thought. Thanks guys!
That's what i thought. Thanks guys!
10s
Veteran
Re: ASA setting meter readings???
So play back out of the camera with 0 setup to a TV or any NTSC unit needs a proc amp here in America to bring the signal up to 7.5 so one can see what it would look like if it were being boadcast. Makes sense. since our cameras use Japanese NTSC and American NTSC is different.
DVX ASA (ISO, EI) I understand here is 640 for the straight line gamma, 400 for the toe & 800 to 100 for knee & shoulder?
Help me find where this subject located I want to read it.
Meters let you know where 18% zone 5 is, the average reflectance in nature. What other ways can consistent shots be taken?
So play back out of the camera with 0 setup to a TV or any NTSC unit needs a proc amp here in America to bring the signal up to 7.5 so one can see what it would look like if it were being boadcast. Makes sense. since our cameras use Japanese NTSC and American NTSC is different.
DVX ASA (ISO, EI) I understand here is 640 for the straight line gamma, 400 for the toe & 800 to 100 for knee & shoulder?
Help me find where this subject located I want to read it.
Meters let you know where 18% zone 5 is, the average reflectance in nature. What other ways can consistent shots be taken?
Barry_Green
Moderator
Re: ASA setting meter readings???
Search here on this forum about a year ago for a big thread on using a lightmeter with the DVX. In progressive-scan mode, 640 is accurate for much of the exposure range, but yes, 400 for f/2.8 light levels, and 800 to 1000 for f/16 light levels (i.e., brightness such that the camera delivers 55 IRE at f/16 corresponds to a spotmeter reading of 800 ISO, when using Normal gamma. When using High gamma, it corresponds to 1000 ISO at that brightness level).
Light metering is absolutely appropriate for film, but is of less value in video, where the exposure curve is not linear. In video a properly-calibrated production monitor is far more valuable (and accurate) than using a light meter. A waveform is even more useful, if used properly. DV Rack is a very affordable way to get a monitor and waveform in the field, but it involves being tethered to a laptop. The DVX also offers a spotmeter which can give you an approximate IRE reading so you know exactly what reflectance/output you're getting... turn on the Marker function, and it reads out the % brightness of whatever you're pointing it at. There's probably a simple mental conversion one could do for Marker readings vs. zones...
Search here on this forum about a year ago for a big thread on using a lightmeter with the DVX. In progressive-scan mode, 640 is accurate for much of the exposure range, but yes, 400 for f/2.8 light levels, and 800 to 1000 for f/16 light levels (i.e., brightness such that the camera delivers 55 IRE at f/16 corresponds to a spotmeter reading of 800 ISO, when using Normal gamma. When using High gamma, it corresponds to 1000 ISO at that brightness level).
Light metering is absolutely appropriate for film, but is of less value in video, where the exposure curve is not linear. In video a properly-calibrated production monitor is far more valuable (and accurate) than using a light meter. A waveform is even more useful, if used properly. DV Rack is a very affordable way to get a monitor and waveform in the field, but it involves being tethered to a laptop. The DVX also offers a spotmeter which can give you an approximate IRE reading so you know exactly what reflectance/output you're getting... turn on the Marker function, and it reads out the % brightness of whatever you're pointing it at. There's probably a simple mental conversion one could do for Marker readings vs. zones...
Z
Zoomforce
Guest
Re: ASA setting meter readings???
Very good info here... one good thing however that a light meter still is good for is for pinpoint accurate contrast ratios using a spot meter to match 2 scenes.. you just cant do that with a camera unless your very lucky
some meteres you need to adjust the ISO for shutter.. but most for a 24fps setting will do a 180 1/48 shutter as default.
Very good info here... one good thing however that a light meter still is good for is for pinpoint accurate contrast ratios using a spot meter to match 2 scenes.. you just cant do that with a camera unless your very lucky
some meteres you need to adjust the ISO for shutter.. but most for a 24fps setting will do a 180 1/48 shutter as default.
10s
Veteran
Re: ASA setting meter readings???
I try use my Spectra incident meter for key to fill ratios. It has a nice feature that remembers two readings and calculates the difference for std. 3 to 1 ratios and such. Sometimes I'm happy with the results & other times I think I need to just wing it.
I try use my Spectra incident meter for key to fill ratios. It has a nice feature that remembers two readings and calculates the difference for std. 3 to 1 ratios and such. Sometimes I'm happy with the results & other times I think I need to just wing it.
blazingoat
Carbonite Member
Re: ASA setting meter readings???
Barry, you mention that a waveform monitor would be even more useful and than a professional NTSC monitor for judging exposure on set. Can you explain what a properly exposed shot would look like on the waveform monitor? Would you just want to make sure that nothing much is going below 0 or above 100-110 ?
Any articles or websites with explanations of how to interpert and use waveform monitors?
thanks. sorry, this is OT from the thread
Barry, you mention that a waveform monitor would be even more useful and than a professional NTSC monitor for judging exposure on set. Can you explain what a properly exposed shot would look like on the waveform monitor? Would you just want to make sure that nothing much is going below 0 or above 100-110 ?
Any articles or websites with explanations of how to interpert and use waveform monitors?
thanks. sorry, this is OT from the thread
Barry_Green
Moderator
Re: ASA setting meter readings???
A waveform monitor lets you see exactly how the video signal is responding. You can tell when something's clipping, when something's crushing, and where your overall signal level is at. Trusting your eyes to a monitor is a good way, but using a waveform lets you know EXACTLY what's happening. Just like in audio recording -- trusting your ears is one thing, but using level meters gives you a lot more information than just your ears alone.
There are scads of documents on the web about waveform monitors. I'd suggest as a start, download DV Rack's trial version and start playing with it, and after you have a basic handle on it, then look at stuff like http://www.videouniversity.com/engineer.htm
A waveform monitor lets you see exactly how the video signal is responding. You can tell when something's clipping, when something's crushing, and where your overall signal level is at. Trusting your eyes to a monitor is a good way, but using a waveform lets you know EXACTLY what's happening. Just like in audio recording -- trusting your ears is one thing, but using level meters gives you a lot more information than just your ears alone.
There are scads of documents on the web about waveform monitors. I'd suggest as a start, download DV Rack's trial version and start playing with it, and after you have a basic handle on it, then look at stuff like http://www.videouniversity.com/engineer.htm