Another reason to NEVER judge exposure off the LCD

B

Barry_Green

Moderator
Hey HMC150 shooters, I may have just figured out a reason why new shooters are having trouble getting quality footage out of this great camera. Simply put, you cannot try to judge exposure off of just using the LCD display. You HAVE to use the zebras and the waveform.

We've had cases of people thinking that their footage looks too dark, or too bright, or there's too much noise because they've been underexposing, etc. Lots of this can be traced to folks using the LCD to judge exposure, instead of using the proper tools (the zebras at a bare minimum, and the waveform preferably).

Here's how you can totally, totally screw yourself over if you just use the LCD: look inside the LCD door at the button in the lower left -- the one called LCD. That button comes factory pre-programmed to control the LCD's backlight level. Try pressing it and watch what happens. The LCD will get darker, and then darker, and then way brighter.

To the uninformed, it looks like you just stopped the camera down a stop or two, and then all of a sudden it jumps back up in brightness. But in reality your exposure hasn't changed at all! It's just the brightness of the camera's LCD panel that has changed. But if you're not paying attention, and that button gets pressed, you could certainly think that now your footage is being underexposed, and open up the iris to compensate -- and that right there could ruin your footage.

Or, if you are used to judging based off one of the lower levels, and you accidentally pressed that button to trigger it into the brightest level, then you might think you're overexposing your footage. Which would cause you to stop down, which would actually cause you to be UNDERexposing, which will make your footage look ugly, grainy, and noisy.

So -- for your own good and the good of your footage, please dedicate yourself to learning how to use the WFM or, at the very least, the zebras. If you're trying to judge exposure off the LCD, you're playing Russian Roulette.

:thumbsup:
 
Barry- great point. I have two questions for you:

1. What is a good resource for learning how to use the waveform monitor?

2. Are you writing a book on the HMC150? I think I saw somewhere that it was in the works. If so, when do you anticpate it being available?

Thanks,

Mike
 
definitely great points Barry. I have been playing with the waveform the past couple days to try and figure it out as well. Im doing my usual setting exposure with the zebras and then checking the WFM to see whats happening on it. Also been using the Auto Iris button to see what the cam does in auto mode then checking that on the WFM too.

Barry to you have any suggestion on setting up the LCD's color and contrast/brightness?
 
I wish they had a realtime histogram.. something in the size + location of the focus assist graph would have been perfect.. I can then use the LCD for composition and focus while a quick glance at the histogram will indicate my scene exposure. A bigass waveform screen that covers up the entire LCD is of less use to me...
 
1. What is a good resource for learning how to use the waveform monitor
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I put about 8 pages on it in the new book, but I don't know of any beginner's guide to waveform monitoring other than that. Hopefully if someone comes across one they'll link to it here in this thread?

2. Are you writing a book on the HMC150? I think I saw somewhere that it was in the works. If so, when do you anticpate it being available?
Click to expand...
Yes, I'm adapting the HPX Book for the HMC150, stripping out the irrelevant parts and adding whole new swaths for the HMC150. It'll probably go to the graphic designer at the end of this month, maybe go to press mid-Apr, maybe on the store shelves Mid-May? Although I feel like I should paraphrase from Red and say "delivery estimates subject to change, count on it." :)

Barry to you have any suggestion on setting up the LCD's color and contrast/brightness?
Click to expand...
For brightness in terms of the BL setting? I always run with it at full bore. Are you talking about the LCD SET menu? I don't bother; I mean, you can try to set it up, but frankly changing the angle of the LCD panel will have a far more serious effect on how the image looks, than changing those menu items! The off-angle viewing has a major impact. Because of that, I usually use the PLUGE trick. Leave the setting at their default settings, then pop on the color bars, and look in the lower right corner, there's a chunk under the red bar that has super-black, black, and gray. Rotate the LCD until the super-black and black bars look the same, and you can just barely discern the gray bar. When you've done that, you're getting pretty much the best/most representative image that the LCD can give you.

I wish they had a realtime histogram..
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There's no histogram, but the zebras give you most of what you'd be looking for. The zebras tell you when your image is starting to cross the threshhold into the overexposed territory, and they do so without cluttering up the image.
 
but the zebra only warns you of clipping highlights.. if you're shooting a scene with extremely high contrast, to bring out shadow details, you are expected to clip highlights, a histogram would help in telling you where the majority of your exposure is at and whether you are under exposing.... I guess the waveform can also be used to indicate this, but it is not as apparent and clear as a histogram.
 
A waveform is like a 3-D histogram. The histogram tells you what the overall exposure of the entire picture is doing. The waveform tells you that for basically every column of pixels. The histogram might tell you that your blacks are chunking up, or that you're overexposed, the waveform will tell you that but it'll also tell you WHERE the blacks are chunking up, or where the image is overexposed. The waveform is a super-duper histogram times a thousand.

But, as implemented on the 150, it does pretty much take over the whole screen. And, unlike the HPX300, it's not transparent. However, on the 150, it only occupies the LCD, so you could use the viewfinder for framing and the LCD for exposure.

Dig into the waveform monitor; if you don't end up liking it a thousand times more than a histogram, I'd be surprised...
 
While i was out shooting yesterday, a slightly overcast day, and i used the zebra function, and i put it to the very point where the zebras were completely gone and the shot was rather underexposed.
 
Strobe Media said:
While i was out shooting yesterday, a slightly overcast day, and i used the zebra function, and i put it to the very point where the zebras were completely gone and the shot was rather underexposed.
Click to expand...

The zebra only tells you blown highlights. .you have to keep that in mind and apply proper context.. You have to decide whether to expose for the highlight or midtone or shadow.. in your case, you exposed for the highlight and the scene was underexposed.. you prolly should have exposed for midtone.

If say you were shooting time lapse clouds, you probably would want to expose for the highlight and set your exposure accordingly to the zebra.
 
Strobe Media said:
While i was out shooting yesterday, a slightly overcast day, and i used the zebra function, and i put it to the very point where the zebras were completely gone and the shot was rather underexposed.
Click to expand...

By making sure there are no zebras just means that the exposure isn't reaching __ level any point in the picture. That doesn't necessarily mean the picture will be exposed correctly. Depending on the lighting situation it might be necessary to have lots of zebras on the screen. You just have to decide on what is your primary focus in the picture and then expose accordingly.
 
Wow, this is a really helpful thread. I just ordered my 150 last week from Adorama and I'm supposed to get it this week. Tonight I ordered the 16gb Transcend with reader from Newegg, and I wish I could read Barry's book right NOW!

I'm really excited to dig into the waveform -- I've used a zebra before (on another 150, the Sony PD-150:)) but with only moderate success. The 150 appears to offer a lot of customization.

I'm subscribing to this thread for sure so everyone keep posting your thoughts and insights on the waveform!
 
Doesn't the manner in which you use the zebra patterns depend on the level for which you have set them? Since there are a dozen values available, it would seem many options are available. I typically use a 90% setting and allow highlights to just push into the zebras and have found that works for me.
 
after a while you will get an intimate feel of how the zebra works.. when shooting a scene with a bright sky and subject in shade, you would expect the sky to be blown out somewhat if the subject is properly exposed.. if there is no zebra on the bright sky, then obviously, your shaded subject is under exposed.. it's all applying the camera's indicated info in proper context.
 
To me, the correct way to use a zebra is to have a spot zebra that shows a range. The HPX300 has it lets hope the HPX200 does also.

However, the 7" Marshall monitor looks VERY intriguing. I don't know if the one-for-one pixel zoom, the vivid edge detection focus indicator, the color map exposure indicator, or the ability to make a full set of blue screen adjustments is the most attractive feature.


http://vimeo.com/372310
 
David,

That Vimeo link is private so nobody else can see it.

Barry etc.,

Thanks, this thread is very helpful.

I have managed to avoid problems with noise etc. so far. What I have done is set zebras to 100% and then I expose so that the zebras affect only the parts of the image I don't mind being blown out. For example, not a bride's dress, but maybe a window. I also use the WFM when I can but this can be a bit tricky when you are busy.

I agree that the WFM is much better than a histogram though, it allows you to know which part of the image has which level of exposure.

One thing I have noticed on the WFM is that there is a region above 100% which looks like maybe an extra 10%, but in this region of the WFM it appears that the increase in brightness is toned down, to create a kind of 'buffer zone'. Am I right in presuming that the parts of the image above 100% are not actually blown out until they reach the top of the 'buffer zone'?

Many thanks,

Stuart
 
Thank you Barry for how to handle the LCD issues.
You wrote:
"I usually use the PLUGE trick. Leave the setting at their default settings, then pop on the color bars, and look in the lower right corner, there's a chunk under the red bar that has super-black, black, and gray"
On my HMC 151 (PAL) the colorbar have nothing under the red bar just a black frame over under the whole colorbar.
Am I missing something or is this a PAL issue?
Regards
/Aje
 
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