Better Color/Film Looks by Under-Exposing
 

After spending a lot of time working the Zebras and histogram to where I can get maximum exposure without clipping I am finding that I get better results - better color and a more realistic look - by a fair amount of under-exposure. I'm talking about outside in very bright natural light conditions.

Does anyone else under-expose? Have an opinion on this?

The bottom line for me is that I am now getting better footage by judging exposure or the picture I want from the LCD screen and ignoring the zebras and histograms a lot of the time.

No! In fact I overexpose by 1/2 stop. While it may look better to you, you're probably losing data by doing this. You're not recording at the full dynamic range the camera is capable of. But, since you seem to be convinced that the quality of your data is accurately represented by what you see before you color grade, you may as well continue with your process.

Because of the nature of the way the camera sensor works, more data is captured at the high end(hi-lites) of the latitude range than at the low end(shadows). It's a log scale. By biasing your camera into the shadows, you're essentially reducing the data available to record. When you color grade this in your NLE, you'll stretch the histogram and end up with more banding than if you had overexposed.

Thanks Bill. My purpose in doing the underexposing was to not need to color correct at all, but you are saying it seems, record at full dynamic range and then I will need use the old "S" curve to bring the shadows out and the contrast up.

Setting exposure is one of those things that is as much an art as a science, and is further hobbled by the occasional realities of our business.

In the old days of film DP's and camera crews had a saying: "Expose for Dailies." They intentionally lit and shot for the uncorrected prints you would end up watching in dailies. As opposed to shooting for maximum technical dynamic range and post coloring processes.

The reason was simple: The director or producers would see dailies and not understanding, trusting, or wanting to pay for what can be done in post might fire a DP for making "cr@p images." Often it was the producer/director who was mistaken - but them's the shakes.

Sometimes, if you are handing footage to a client right after a shoot for example, you still have to shoot for dailies.

The rest of the time when you can shepherd your images through post, through DI and to delivery its your JOB to preserve dynamic range, to shoot to make the post guys lives easier. As you often hear on sets today, "Get the data!"

I tend to expose the image as much to the right of a histogram as practical without allowing any clipping. i.e like you were learning to. I don't "overexpose" as Bill says- but that may be because we define over exposure differently.

(I say overexposure is the technical condition when image highlights have exceeded the ability of your camera to record detail. i.e. When highlights clip.)

Then I lower effective exposure in post or DI. That's the beauty of this workflow. This gets me right about where you are exposing by eye with the LCD- but it also tends to save me more data in post, like Bill is talking about.

Sometimes that is not the smart way to get the look I want, but only experience teaches me (and I am still learning of course) when that is.

The point I am trying to make is that you have to think of your total workflow. If you expose like we have all been talking about you have way more post options, and the look can be very malleable. If instead you shoot for dailies, then you may be stuck with what you shot.

You need to be able to shoot both ways.

So, how much tweaking can one do to the data before deterioration is visible? By deterioration, I mean banding in smooth tones (e.g., skies) or noise in the shadows.

My assumption is that once the EX1 has been set (gamma curves, black point, etc.) any adjustment away from those settings can contribute to image degradation.

We often get to talking about edge cases as if they are ordinary situations.

Even for a fairly non-optimal image you can do quite a bit with EX1 footage.

So, while you are right that any adjustment contributes to image degradation- you have to understand there is quite a bit of adjustment you can do before that degradation becomes visible.

In other words- a lot of the words traded here only concern people with deep post pipelines.

Interesting.

In digital stills using CMOS and raw images underexposing is better than overexposing. Once its over exposed the data is lost whereas with underexposing the data is recoverable.

Hi Brendan,

The opposite is actually more accurate. This is a great read:

http://www.adobe.com/digitalimag/pdfs/linear_gamma.pdf

You do want to avoid clipping, but overexposing without clipping is a great practice.

You can tweak downwards (moving lights towards black) without much degradation. Trying to pull darks to light, noise shows up very quickly.

Thanks for the responses. I'm not a full-time video producer, so these answers help me. I do make my living with still photography, and when shooting in RAW mode (as the Red One does) it is better to expose for a lighter image (i.e., "shoot to the right" of the histogram). Post processing a well-exposed RAW file can include radical moves in curves, saturation, color temp, and histogram adjustment without any degradation to the image. It's wonderfully flexible. If the image has been slightly over-exposed, without clipping, then the results in post can be noticeably better than the same scene that's been "correctly" exposed/captured.

However, the EX1 captures data and processes it for output. So my assumption is that the exposure, color temp, gamma points, etc. must be nailed for the best footage. How can one tell when the image has deteriorated due to excessive post-production alterations? Are there tools in FCP or even Photoshop that can be used to show image degradation?

Hi Chris,
In terms of exposure, you are still going to be way better off pushing right so long as you don't clip. Not doing so is "wasting bits". Just like with an in camera jpg in still photography, you will still be able to move things left after the fact with excellent results.

Alexander....

you're absolutely correct. thanx for correcting my sloppy terminology. Of course, I never meant to advocate "overexposure". What I meant to say is that I expose to the right side of the histogram. Any real "overexposure" is lost data.

One other point to note...Histograms that show just luminance, no chroma channels, are inherently incomplete. It's possible to have the luma properly exposed and still blow one of the color channels, usually blue.

Good point.. which started Piotr's concerns.

This is true. When the EX1 is at max histogram and the Vegas luminance is at max the blue is often blown. I always have my Vegas histogram show RGB.

[QUOTE=Bill Ravens;830215]Alexander....

you're absolutely correct. thanx for correcting my sloppy terminology. Of course, I never meant to advocate "overexposure". What I meant to say is that I expose to the right side of the histogram. Any real "overexposure" is lost data. QUOTE]

I think you had it right initially. Overexposure can be a photographic choice that involves no clipping (blown highlights). Often pushing right will be overexposed, but will preserve all image data.