wfm
- Thread starter MTS
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Spec-Comm
DVXuser Sponsor
Hello MTS,
http://en.wikipedia.org/wiki/Wave_form_monitor
http://www.hamlet.co.uk/support/apps/waveformmonitorbasics.html
The Waveform Monitor is used to set up exposure. Light is converted to units called IRE and they range on a WFM from 0-100. Some of the really nice ones will go from (-50) to 120. 0=Black, 100=White. -40=SYNC and some other things are kept in the sub-black ranges.
If you want to use a WFM to check exposure, you will make sure the brightest object in your frame is at or below 100 IRE. Sometimes this doesn't work though. For example, if you want to shoot a scene outside with landscape and a bright sunny sky, without ND Grad filters, you will have to "blowout" or over expose the clouds to get the proper exposure on the landscape.
The best thing to do is to go in to a dark room and light a single piece of white paper and play around with it. You can see how the white paper and the darkness of the room translates to the WFM.
I hope this helps.
Sincerely,
Andrew Hoffman
Vice President
Specialized Communications Corp.
20940 Twin Springs Dr.
Smithsburg, MD 21783-1510 USA
800-359-1858 (US)
301-790-0103
Fax: 301-790-0173
andrewh@spec-comm.com
www.spec-comm.com
www.twitter.com/speccomm
http://en.wikipedia.org/wiki/Wave_form_monitor
http://www.hamlet.co.uk/support/apps/waveformmonitorbasics.html
The Waveform Monitor is used to set up exposure. Light is converted to units called IRE and they range on a WFM from 0-100. Some of the really nice ones will go from (-50) to 120. 0=Black, 100=White. -40=SYNC and some other things are kept in the sub-black ranges.
If you want to use a WFM to check exposure, you will make sure the brightest object in your frame is at or below 100 IRE. Sometimes this doesn't work though. For example, if you want to shoot a scene outside with landscape and a bright sunny sky, without ND Grad filters, you will have to "blowout" or over expose the clouds to get the proper exposure on the landscape.
The best thing to do is to go in to a dark room and light a single piece of white paper and play around with it. You can see how the white paper and the darkness of the room translates to the WFM.
I hope this helps.
Sincerely,
Andrew Hoffman
Vice President
Specialized Communications Corp.
20940 Twin Springs Dr.
Smithsburg, MD 21783-1510 USA
800-359-1858 (US)
301-790-0103
Fax: 301-790-0173
andrewh@spec-comm.com
www.spec-comm.com
www.twitter.com/speccomm
DaFireMedic
Well-known member
I didn't even take it into consideration when buying the HMC, but after 3 months I've found the WFM to one of the most useful features for getting a quality video image. I couldn't be more pleased that they included this feature.
bgreenstone
Member
Same here. What I do is watch what I'm shooting with my right eye in the viewfinder, and then use my left eye to view the WFM on the external display. I could not shoot anything w/o the WFM.
-Brian
-Brian
Brad_C
Active member
Ok ok ok......
I'm still a noob to a lot of this but I think I'm starting to understand it a little bit.
So this is somewhat comparable to using the scopes I use in MBL to set the proper exposure for a scene, right? So I'm looking for a slightly deeper explanation about something....
I set my scopes in MBL to show up to 2.0 even though anything over 1.0 is overexposed and blown out. (I just want to see more of the graph I guess.) So would the 1.0 I see in MBL's graphs be the equivalent of 100 IRE (top line on the WFM graph) since going over both result in over exposure?
I played around with the WFM after reading this thread and it seems that I'm right, but I'm not afraid to admit that I'm wrong if proven so. haha
Take it easy on the new guy. :crybaby: haha
:thumbup:
I'm still a noob to a lot of this but I think I'm starting to understand it a little bit.
So this is somewhat comparable to using the scopes I use in MBL to set the proper exposure for a scene, right? So I'm looking for a slightly deeper explanation about something....
I set my scopes in MBL to show up to 2.0 even though anything over 1.0 is overexposed and blown out. (I just want to see more of the graph I guess.) So would the 1.0 I see in MBL's graphs be the equivalent of 100 IRE (top line on the WFM graph) since going over both result in over exposure?
I played around with the WFM after reading this thread and it seems that I'm right, but I'm not afraid to admit that I'm wrong if proven so. haha
Take it easy on the new guy. :crybaby: haha
:thumbup:
Ok ok ok......
I'm still a noob to a lot of this but I think I'm starting to understand it a little bit.
So this is somewhat comparable to using the scopes I use in MBL to set the proper exposure for a scene, right? So I'm looking for a slightly deeper explanation about something....
I set my scopes in MBL to show up to 2.0 even though anything over 1.0 is overexposed and blown out. (I just want to see more of the graph I guess.) So would the 1.0 I see in MBL's graphs be the equivalent of 100 IRE (top line on the WFM graph) since going over both result in over exposure?
I played around with the WFM after reading this thread and it seems that I'm right, but I'm not afraid to admit that I'm wrong if proven so. haha
Take it easy on the new guy. :crybaby: haha
:thumbup:
I believe that's something of an RGB parade scope and is pertinent to establishing the Red, Green, and Blue levels relative to each other.
Brad_C
Active member
That I understand. I know the two are completely separate from each other. All I was intending to say is how to read the scope itself. They appear to react to light the same way so by understanding the RGB scopes, it's at least helped me understand how the WFM reacts.
....or maybe I don't know what I'm talkin' about. :huh:
Barry_Green
Moderator
The zebras only show you a binary representation: this segment is "hotter" than your predefined threshold. The waveform monitor shows you the exact level of every element on your screen.
So with the zebras you know something is 70 IRE or more, but you don't know if it's 75 or 90 or 105 or whatever. With the waveform monitor you see exactly what it is, across the entire screen.
Zebras are about 3% of a waveform monitor.
So with the zebras you know something is 70 IRE or more, but you don't know if it's 75 or 90 or 105 or whatever. With the waveform monitor you see exactly what it is, across the entire screen.
Zebras are about 3% of a waveform monitor.
Is 100 IRE the top of the monitor? The HMC doesn't show numbers on the WFM monitor.
VideoMaker
Well-known member
I'm still trying to get my mind around wfm. I'm very familiar with histograms in a DSLR. What advantage does wfm offer over histogram? I assume it must be advantageous for video.
Barry_Green
Moderator
The histogram is a graph of how much each level of brightness is present in your picture, but it doesn't tell you *where* in the picture that brightness is. It's like a one-dimensional scale. Technically two dimensions, but as per comparison to a waveform, I'm gonna stick with one. 
The waveform is three dimensional. It tells you on the horizontal axis exactly what is happening with your picture, and on the vertical axis it tells you the brightness for that segment, and in the depth of the image (the brightness or dimness of each pixel) it tells you how much of the image is at that brightness level.
The waveform is three dimensional. It tells you on the horizontal axis exactly what is happening with your picture, and on the vertical axis it tells you the brightness for that segment, and in the depth of the image (the brightness or dimness of each pixel) it tells you how much of the image is at that brightness level.
Thomas Lew
Well-known member
The histogram is a graph of how much each level of brightness is present in your picture, but it doesn't tell you *where* in the picture that brightness is. It's like a one-dimensional scale. Technically two dimensions, but as per comparison to a waveform, I'm gonna stick with one.
The waveform is three dimensional. It tells you on the horizontal axis exactly what is happening with your picture, and on the vertical axis it tells you the brightness for that segment, and in the depth of the image (the brightness or dimness of each pixel) it tells you how much of the image is at that brightness level.
NOW IT MAKES SENSE TO ME Thank you Barry
VideoMaker
Well-known member
Thanks Barry. I also found this series of tutorials on waveform monitors and vector scopes. They fill in additional technical details. I found this statement interesting:
Can you suggest any reading to better understand using these two monitors when shooting with the HMC150? Practical examples would really be useful for me.
It takes some experience to set iris opening using the observed waveform. Typically, spikes resulting from specular highlights (the kind of peak that results from jewelry and polished musical instruments) are ignored. Automatic iris systems work from the Y (luminance or brightness) signal and ignore chroma. They also partially average the signal to ignore small specular highlights and also ignore the top third or quarter of the picture so that accidental inclusion of overhead lighting fixtures will not affect the picture.
Can you suggest any reading to better understand using these two monitors when shooting with the HMC150? Practical examples would really be useful for me.
The histogram is a graph of how much each level of brightness is present in your picture, but it doesn't tell you *where* in the picture that brightness is. It's like a one-dimensional scale. Technically two dimensions, but as per comparison to a waveform, I'm gonna stick with one.
The waveform is three dimensional. It tells you on the horizontal axis exactly what is happening with your picture, and on the vertical axis it tells you the brightness for that segment, and in the depth of the image (the brightness or dimness of each pixel) it tells you how much of the image is at that brightness level.
some1shero
Active member
As many people have said before the WFM will save your footage. Do NOT trust your eyes. The WFM never lies to you and ALWAYS trust it, especially under low light conditions.
