Waveform monitor and Vectorscope

K

Ken Neumann

New member
I am looking for a link or book to explain how to understand the functionality of the waveform and vectorscope readouts on the HMC 150. In Barry Green's handbook, I read that using these tools can tweak the clarity of the video better than relying on LCD screen as a monitor. What is the camera operator supposed to look for when looking at the waveform monitor, and what do you do to make the video as clear as possible? Also what does one do to optimize the use of the vectorscope? Any thoughts? Thank you in advance!!
 
I don't know how well this answers your question, but I'll give it a go.
I don't think using the word "clarity" is best when talking about the WFM and scope. When I think of clarity I think of focus.
From what I understand, the WFM is for precise exposure control monitoring and the vectorscope is for color balance monitoring. Tweaking these two characteristics would immediately affect the intensity, temperature and color of your image.
 
Vectorscope/ waveform is really going to be useful if you plan on using footage for TV broadcast. It will let you know when you video signal goes past IRE100. NTSC model camera's have IRE setup which will also help the video signal blowing out.

As far as clarity and sharpness goes,,, this is governed by the scenefile setings and how well you use you focus assist button. You only need be a tiny bit off focus with HD and it kills the shot. The focus assist is a must, Barry's book will give you a wealth of knowledge for all this stuff.
 
waveform/vectorscope & focus control

waveform/vectorscope & focus control

Hi,

I was basically asking someone the same question at the reason DVExpo meeting in LA. We had a bunch of folks gathering at the Panasonic booth, and querying existing users about critical focus on the HMC-150. The unanimous opinion of the group gathered seemed to suggest that, if you're shooting narrative films and taking the time to light your scene, and going for max production value, they would use an external HDMI monitor, which is what I have been shopping for since I bought my 150 a few months ago.

Randy
 
I can also recommend Barry`s HMC150 book. It covers the essentials for the Waveform monitor and Vectorscope in plain English.
 
Ken Neumann said:
In Barry Green's handbook, I read that using these tools can tweak the clarity of the video better than relying on LCD screen as a monitor.
...
Also what does one do to optimize the use of the vectorscope? Any thoughts? Thank you in advance!!
Click to expand...

I have the book too, and am asking the same questions. The book does not help here (either) so the vectorscope is so far a mystery to me. A few "good", "bad" etc screenshots from the HMC's own vectorscope would have helped us a lot. I am as eager as you to learn how to use my HMC 151, and any knowledge on how to judge the camera's vectorscope screen is very much welcome.
 
It is very simple if you imagine the vectorscope as a ColorWheel - R, G, B and C, M, Y; with grayscale in a Center to the color at the outerside.

I will try to illustrate this in next post. Working on it...
 
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Okay, you can use the waveform to help determine your focus as well. You will have to pull out your camera to see the impact. Watch the squiggly line and see how it changes as the camera comes into focus. You should see more detail in the squiggles. As you watch this enough and check your work, you can get to the point that you trust it, but it takes a bit of practice and knowing what to look for.


Hope that helps,

Jan
 
Sorry for Late...

As I see now, many people here are still getting confused with Waveform and Vectorscope, since there is no detailed explanations in HMC Manual.
So, as I said, I made some Graphical illustrations for easy understading of Waveform & Vectorscope.

Trying to explain in very simple language, I hope it will help you.

Lets Start...

Waveform Monitor:
Basically used for monitoring exposure, it tells you White Levels and Black Level in your scene, from Left to Right.
If it's showing something at 90-100% in left, it is pointing at over-exposed(or White) section at the left side of the scene.

Same with 0% which shows you Black section of the scene.

You can use Zebra all the time to avoid over-exposure. Just set the correct percentage you want to see in the Zebra.
waveform.jpg

Vectorscope:
Vectorscope is a tool for monitoring the Color Levels in the Scene. It shows you the balance of the colors in the scene.

If you are wondering what exactly the Points(one in center and six around it) do show, don't be afraid.
The six points just represent six colors - Red, Green, Blue(RGB) and Cyan, Magenta, Yellow (CMY).
And the center point represent Desaturation (Black-White).

If the look of your scene is Redish Hot, you can see the particles of the Vectorscope are Moved towards Red-Yellow points.
This is very useful for seeing which colors, in what level are present in the scene.

Vectorscope get affected by SceneFile settings too.
vectorscope.jpg

Made only for DVXuser Forum.
 
Basically the waveform monitor is a great way for telling exposure. It can help with many things, for example when lighting a green screen evenly you can look at your waveform and see if there are any uneven spots on your screen ( the greenscreen in the waveform will look like a thick line since the exposure should be the same)

You can use it to set your Pedestal as well. Put the lenscap on the HMC and look at the waveform, notice the noise? (the line which is near 0 is not even) start lowering the master ped and you will see that line quiet. This is a great way to get less noisy blacks without crushing them too much.

Waveforms as you learn to read them are a great way to know where your exposure is on your camera. You can't always trust your monitors or LCD to tell you when things are over exposed or underexposed, settings can be changed especially if the monitor is not calibrated properly and thus can appear dark/light. Waveforms don't lie.

Vectorscopes are for color readings and in my experience is less useful on the field. Some TV eng types have some tips/things they do with a vectorscope on the field to insure good skintones, but I'm not very familiar with it, maybe someone will chime in. For the most part the vectorscope can be useful when using color charts you can switch the different gamma settings on a color chart and see what the camera is actually doing to the image. This can help you understand why that cinelike D or B.Press looks so nice to your eye. One of the easiest ways to see the vectorscope in action is with white balance. Hold a white item in front of the camera when its white balance is off and you will see the image shift towards that color, as you press white balance you see the camera attempt to shift the image towards the center.

Hope that helps,
 
evsdan said:
Vectorscopes are for color readings and in my experience is less useful on the field. Some TV eng types have some tips/things they do with a vectorscope on the field to insure good skintones, but I'm not very familiar with it, maybe someone will chime in. For the most part the vectorscope can be useful when using color charts you can switch the different gamma settings on a color chart and see what the camera is actually doing to the image. This can help you understand why that cinelike D or B.Press looks so nice to your eye. One of the easiest ways to see the vectorscope in action is with white balance. Hold a white item in front of the camera when its white balance is off and you will see the image shift towards that color, as you press white balance you see the camera attempt to shift the image towards the center.
Hope that helps,
Click to expand...

It helps! Thanks for this, it is clear talk. I have wondered how to really use the vectorscope, because - after I have adjusted the white balance - what more can I do? A related question is to what extent I should film in neutral and add cinematic color corrections in post, versus what the advantage is to do this already when recording. What do you think?
 
evsdan said:
You can use it to set your Pedestal as well. Put the lenscap on the HMC and look at the waveform, notice the noise? (the line which is near 0 is not even) start lowering the master ped and you will see that line quiet. This is a great way to get less noisy blacks without crushing them too much.
Click to expand...


I've noticed an odd thing and I have decided to post it here.

I have done this with the waveform monitor (many times). The odd thing is that with the HMC150 I am noticing "noise" on the line at various negative pedestal settings. What I mean is, I turn down the pedestal and see no noise on the line, but go down just one or two steps and I see noise again, turn down pedestal again and noise disappears. Repeat.

Shouldn't it just stay gone once you lower the pedestal enough? At least that is what my brain logic is telling me.
 
evsdan said:
You can use it to set your Pedestal as well. Put the lenscap on the HMC and look at the waveform, notice the noise? (the line which is near 0 is not even) start lowering the master ped and you will see that line quiet. This is a great way to get less noisy blacks without crushing them too much.
Click to expand...

I didn't even know about this trick. Sweet, you learn something new everyday.
 
Some Waveform Noise tests

Some Waveform Noise tests

I did some experimenting with the iris closed and changing the detail, vdetail and master pedestal.

Lowering Detail will lower noise on the "bar", as will lowering pedestal. BUT the noise can change depending on what pedestal you are at.

For example. On Cine D gamma:

With the detail and vdetail at -2 (detail is the main factor), the "noise" will change with pedestal from 0 to -11. Sometimes increasing, sometimes decreasing as we go down (could this have something to do with the way the cine d gamma works?). BUT at -11 there is no noise and the bar is very thin. Going below this number on MY HMC150 does not change that any further.

Now with the Detail and VDetail at -3, I thought that magic pedestal number changed to -6. But what it really effects are the pedestal numbers between 0 and -11.

I also noticed that you really do need to black balance every time you change a battery/ power off, or change recording settings. Especially when you power off. It effected the WFM every time. Changing recording modes did not effect the noise as often but why risk it?

Now when you throw DRS into the mix things get really interesting.

At detail(s) at -3 (tested at 72060P) I can get a clean "bar" at
DRS 0: ped -5
DRS 1: ped -9
DRS 2: ped -6
DRS 3: ped -8

(And no those numbers are not a typo.

Can anyone explain this? What exactly is each DRS setting doing? From what I understand they effect black level and knee somehow but the white paper I read did not go into this much.

I didn't retest at details at -2 but I assume it will also be funky unless the ped is -11 or lower. (similar to -3 details tests).

Of course these tests are all based entirely on the "noise" on the line on the WFM.
 
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The master pedestal is changing how the darkest regions of the image are rendered. The lower you set it, the more "crushed" the black/shadow areas of your image will be. Noise lives down in the dark area, so if you crush all that shadow detail down to black, yes you can eliminate some noise. However, you'll also be giving up detail in the shadow areas.

The higher DETAIL settings will actually accentuate the presence of noise, by adding outlines (edge enhancement) to the noise. So the higher the detail level, the more visible the noise will be. The noise is still there, but higher detail levels accentuate it or draw attention to it. Without changing anything else at all, you'll notice a HUGE difference in noise levels between DETAIL -7 and DETAIL +7.

DRS adds gain to the shadows. So it magnifies the amount of noise that's there. IIRC, DRS 1 adds about 3dB of gain, DRS 2 adds up to 6dB, and DRS 3 adds up to +18dB. Those figures were based on observation, but there is no technical paper that describes exactly what DRS does that I've ever found. The conclusions I came to about DRS is that it lowers the brightest areas and adds gain to the shadow areas, but it doesn't do so globally on the entire frame. It can do so only in spots where it thinks such enhancement are necessary.
 
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