Ok, like my subject says.
When it comes to SD video is it better to slightly underexpose footage or slightly overexpose. From what I've seen I've found it better to slightly underexpose and change the levels in post.

My class just went to Nashville today and used a telecine to transfer our 16mm to video. With this it was better to overexpose than underexpose. One group shot at about F2.6 or F2.8 during the day against an almost white background. Using the telecine the operator adjusted it and it looked pretty good, although maybe somewhat grainy. We did a poor job lighting most of our background and the we couldn't get anything out of the background.

So its better to overexpose film, but what about video?

Neither... It's better to expose it properly!

Digital is a little different from film. In digital, it's better to overexpose, slightly, then bring the exposure back in post. Overexposed shots will recover blown highlights easier than underexposed shots. Shadows tend to lose the info that was there, while clipped highlights are mildly recoverable. Unfortunately, in order to see all the data that is there, and whether it's truly clipped or not, one needs a histogram. Some video cameras are now putting histograms in the display. Digital still cameras were enlightened a while back and actually show all three color channels in a histogram for each...which is the right way to expose digital properly.

If you're using a decent form of compression like Cineform - i'd say it's better to underexpose...

I've been back and boosted the levels like CRAZY, and you'd be so surprised at the amount of information in those dark shadows... This is again, using uncompressed, or a good compressor like Cineform..

Just my two cents..

From my experience I have better luck if it is under exposed, because if it is over exposed there in no information there.

Bob Trimmer

Over exsposure and clipped highlights are two different things.

For me and my DVX I find it better to overexpose a bit but not blow my highlights. Then I take it down in post and have less noise in the image.

Blown highlights are just that, blown.

ok , im going to really simplifiy it cause it works for me.

have you zebra bars?
if you have keep them off the faces and out of the overall shot as much as possible or you are in trouble.

You can bracket exposures and do a test. An example of my test:

http://glennchan.info/video/exposure/exposure.htm

When shooting old-fashioned FILM, the rule of thumb is:

-- You can OVER expose negatives, since the film has the latitude to record overexposed highlights (you just have to give more exposure to the print, in order to bring out the highlight details).

-- You should NOT over expose reversal film, since the highlight info will be destroyed. But you can slightly UNDER expose reversal film, and get back the highlight details along with most of the shadow details.

I would have thought video was more like reversal film. I see Bill and Bob have differing opinions on this.
Sounds like it's time for you to do some tests! 8-)

Ken Hull

On a bright sunny day, I'd go slightly over vs. slightly under. But, it's a fine line. Slightly over, and FCP allows for easy safe filtering, just slap the filter on the clips, and all areas of the image that are over the set limit are clipped. This way, I get to keep more detail in the shadows and more easily stay out of the muddy blacks that lead to bad contrast.

On a uniform cloudy day outdoors, I think it might be better to underexpose slightly, since light is so even across all objects in the frame. Then, bringing levels up across the board to get the most dynamic luminance range possible.

Most of the time indoors, there's really no good excuse for missing the exposure.

As far as zebras go I like to see them only on the brightest highlights and maybe spread over some to the next level up...but it depends on your camera .....

...use your eyes and look and see what you see as the brightest surface that you are shooting....then look back through the camera and check the zebras...

example:
white guy with red guitar/white pick guard outside in sun...pick guard will be totally white and the zebras might not even completely show up in it...his face is darker but lighter than his black leather jacket and jeans....find the medium exposure for the shot and work from there with it...

I would end up with a tad of zebras on the brightest highlight on his face and the pick guard would be possibly full of zebras or even losing them ,because whites are usually 2 stops brighter than 18% gray....

I still keep that rule in my head from film school from 15 years ago.....
but this is how I expose for my shots and then add the fidgeting around a half stop ......it really is a fine line of exposure especially in the sun....

*but first you must know your camera well and how it exposes for latitude.... I go outside and shoot video of different things under different lighting conditions and narrate what I am seeing on the zebras....that has really helped me...also do this for tungsten lights too....and your on-camera light too.

as far as you stopping down your zebras to where they just go off...guess that would put you about a stop under....you should be able to bring the exposure back up in post especially in FCP .....


I would rather underexpose slightly than over .....

There is also a tecnical reason to overexpose digital (both video and stills) rather than underexpose if the subject range fits within the exposure latitude: The tonal gradiation is finer in lighter parts of the image. This means it is possible to darken the image without any quality loss, but as the shadow parts of the image have more coarse gradiation in the file, making the image lighter "rips the tones apart" so to say.

Of course you can over/underexpose only when the total tone scale easily fits withing the available range. If not, the only way is to expose correctly, which sometimes means a compromise between loosing the shadows and/or blowing the highlights.

I always overexposed my color negatives by at least a stop..sure worked out well indeed.

Wow, thank you all for the responses so quickly. From the majority of the responses, when I've been faced with this decision I have been exposing wrong(underexposing) I guess I should do what Glenn Chan suggested and bracket my shots then compare and adjust in post.

If you already know where your optimum level is, why would you choose to shoot over or under it, and then have to adjust it in post?

OVEREXPOSE doesn't mean blow the highlights! Blown highlights are gone forever. That's why it's so critical to use a 3 channel histogram. A lightmeter will tell you you're OK when one color channel is blown.

Sometimes the correct answer is not what your were looking for.

You asked if it was better to over expose SD video or under expose SD video and fix in post.
The correct answer is neither. It is better to expose SD video properly when shooting by using industry standard measurement tools, like a light meter, waveform monitor, vector scope, or simply using the built-in zebra bars on your camera.

Nothing was said in your first post about how much time or money you had for a shoot.

It's kind of like rebuilding an engine and asking if it is best to under tighten the bolts, or over tighten the bolts. The correct answer is neither. It's best to tighten the bolts to the recommended torque setting by using industry standard measurement tools, like a torque wrench.

Sorry, David, I beg to differ.
Built in light meters do a fair job of determining proper exposure, however, it's not necessarily optimum exposure. In the context of getting the most image information recorded on your record media, in most cases it is better to expose on the high side of the bandwidth than on the low side. The built in lightmeter won't advise you on the subtleties of how to do this, unless you dial some exposure bias into the reading. This is tricky, however, because the amount of "overexposure" that is truly optimal changes according to the scene characteristics. No averaging meter sees well enough to predict the best, ie optimum exposure for every scene. The meter only shows you what the optimum exposure is for an 18% grey scene. How many perfectly defined 18% gray scenes do you run across on every shoot?

That all being said, one is better off, in digital imaging, to err on the high side, that is to overexpose, as long as the highlights aren't blown. How does one tell if the highlights are blown? A 3 channel histogram is the most accurate way. This is commonly accepted knowledge, not my invention or opinion.

BTW, "standard" torque wrenches can be grossly inaccurate if not used properly. They measure stiction, not true torque as seen by the head of the bolt. There are precision instruments available when the sledgehammer approach isn't close enough.

As far as zebras go I like to see them only on the brightest highlights and maybe spread over some to the next level up... but it depends on your camera.
Where do you set your zebras? 80%? 90%? or 100%?

100% means it's clipping info. Not much clearer decision point than that.

Most cameras usually don't clip at 100%. They will record a little headroom above that. On particular cameras you can set that clipping level.

2- I highly suggest you do your own tests.

If you expose very bright, the detail will first hit the camera's knee circuit and then it will clip. The behaviour of the knee differs between cameras and depends on menu settings.

If you expose too dark, bringing up exposure in post will increase noise.

Color correction/grading also plays a role in this.

3- Learn your camera. Learn how the zebras + what you see in the viewfinder and monitor correspond to your exposure level. Some zebras can be set between 70~100... this makes a difference obviously.

OVEREXPOSE doesn't mean blow the highlights! Blown highlights are gone forever. That's why it's so critical to use a 3 channel histogram. A lightmeter will tell you you're OK when one color channel is blown.

So where would you get one of these and could it connect to the H1? That would be cool :)

Thanks
Tony

Only place I know of would be to use Adobe Audition(aka Serious Magic's HD Rack). Unfortunately, Adobe wants an arm and a leg for it. And that means you have to lug a laptop around to make it work. Some of the newer cameras, like the EX1, have built in histograms, but, the video camera makers still haven't wigged to the fact that a monochrome histogram is not the whole story, you need a 3 channel histogram, because you can blow one channel and the mono histogram won't show it.

Er- um - I think you meant On Location, now from Adobe, formerly Serious Magic.

Thanx Jim. Hard to care much about the long fingers of adobe.

...guess I'll just keep riding the zebras.....lol

Where do you set your zebras? 80%? 90%? or 100%?

I shot last week on 85%.....

You asked if it was better to over expose SD video or under expose SD video and fix in post.
The correct answer is neither.

I get your point, you sound like someone who has a strict way of working which is fine , each to their own. Personally i never have the time to set up waveform monitors and i think using a light meter with digital is pointleless because unlike film you can see in the viewfinder or monitor the image you are getting.

To answer the origional question.....I went to a lot of seminars at the Edinburgh film festival this year and one of them was a post digital grading company, they had examples of work and had their grading desk at the front of the auditorium. They said it is best IF ANYTHING to underexpose slightly, now of course as David said its better to expose correctly but once highlights have blasted out they are gone. (there, you heard it from the horses mouth)

The botom line is if you are going to do anything other than expose correctly (the correct exposure being the farthest you can go without anything blasting out) then you should underexpose slightly as this can be fixed unlike overexposure.

Having said that I personally dont even use zebras, i judge the image by eye and iv never had any problems.

Andy.

I think using a light meter with digital is pointless because unlike film you can see in the viewfinder or monitor the image you are getting.

I guess I'm just an old school fool. Before I ever pull a camera out of it's case, I use my light meter and color temp meter to instantly check exposure level, lighting ratios, and color temperature.

to rely on what you see in the viewfinder is a fool's errand. the viewfinder has brightness and contrast controls that completely negate any accurate representation of the real image lighting. The only time I would rely on a viewfinder for anything but framing is when it's a reflex image.
time and time again, in this business, I run into people who are so completely stuck in their belief system that they can't accept the latest technological truths. Actually just means more business for me, so have at it.

roy....

there are very valid reasons for shooting at zebra settings other than 100%. For example, skin tends to expose around 70%. Setting the zebra for 70% and exposing to just remove zebra from skin works very well when the subject is primarily a talking head.

to rely on what you see in the viewfinder is a fool's errand. the viewfinder has brightness and contrast controls that completely negate any accurate representation of the real image lighting.

The brightness and contrast levels don't make that much of a difirence, you can still tell when its blasting out, set them to where your happy and leave them there.

Far too many people on this site are so caught up in trying to sound like they know whats best for everyone else like they're better than the rest of us, while your setting up your waveform and reading your light meter i'll be three set ups ahead of you and i guarantee the exposure will look evey bit as good.

i was merely saying how i do things not what everyone else should do but you have to drag this thread through the mud and start name calling....grow up.

Dave i never said your a fool for using a light meter i just said i personally think they're pointless when shooting digital.

Andy.

I have shot digital stills professionally 6 years now (after 20+ years of film), and never have needed a light meter since. Histograms have taken their place. Even when shooting with studio flash I just make an educated quess, shoot a test and adjust once or twice with histograms. Goodbye nasty, dirty polaroids...

Anybody want to buy a Minolta Multimeter MkIV with spot attachement?

Video: electric viewfinder itself is grossly unreliable, as it's adjustement can be way off. Zebra feature is the savior, set the zebra to 100%, let the highest highlights just touch the zebra and you are just about perfect, shadows have to look for themselves. When I shoot heads, fairly evenly lit (classic 3 point lighting), I set zebras to 80% and skin highlights just touching the 80% mark. That's it. Perfecto.