How can I expose to the right with a DSLR if the meter targets 18% gray?
Asked 7/2/2011
1 views
2 answers
0
I understand the idea behind expose to the right (ETTR): digital sensors usually give better signal-to-noise performance when you capture as much light as possible without clipping important highlights, then reduce exposure later in post if needed. But a camera’s built-in meter is generally designed around a midtone/18% gray assumption. So if I want to use ETTR, how do I actually set exposure? Do I ignore the meter and use the histogram after a test shot? Is exposure compensation the practical way to push the exposure brighter without blowing highlights?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
15y ago
2 Answers
9
I think the article is referring to using the histogram to judge exposure, after a test shot has been taken. Using the histogram as a guide you can increase exposure until the top of the histogram hits the right edge, indicating clipping may start happening.
If you have to rely on the in camera metering (which will meter assuming 18% reflectance as you suggest) then you can simply use exposure compensation to correct the camera exposure up a stop or two in order to expose to the right. Using the histogram is much more accurate however!
Whilst we're on the subject the luminous landscape article is a little simplistic and wrong in a few areas. Expose to the right doesn't increase detail it increases signal to noise ratio. The more light you let in, the more signal you get and hence better SNR. This even applies to increasing ISO in order to expose to the right, you increase the analogue signal above the noise floor by amplifying it.
Exposing to the right is not always desirable. Increasing SNR can come at the expense of limiting colour fidelity. The higher you go up the brightness scale the fewer colours can be represented.
Finally on every DSLR I've seen, the histogram you get is based on a jpeg image the camera creates - even if you shoot raw. I know of no camera that gives you a histogram of the raw values. This means you have to be careful of your jpeg settings (saturation and contrast) in particular when setting exposures based on the histogram.
Originally by user1375. Source · Licensed CC BY-SA 4.0
user1375
15y ago
0
Generated from our catalog & community — verify before relying on it.
Yes: for ETTR, the practical tool is usually the histogram after a test shot, not a gray card.
Your camera meter still tries to place what it sees around a midtone, so if you rely on metering alone you can add positive exposure compensation to push the exposure brighter. Then check the histogram and increase exposure until the data is as far right as possible without clipping important highlights.
That said, ETTR is often overstated. It does not create more detail; the main benefit is improved signal-to-noise ratio because you captured more light. In many real scenes the gain can be small, while the risk of blown highlights is significant.
Also, ETTR is most useful when you truly have extra highlight headroom. If you can simply lower ISO instead of overexposing at a higher ISO, that may amount to nearly the same thing.
So the workflow is:
- Meter normally.
- Add some positive exposure compensation if needed.
- Take a test shot.
- Use the histogram to nudge exposure rightward.
- Stop before important highlights clip.
In short: use the meter as a starting point, but use the histogram to finish the exposure.
Recommended products
UniqueBot
AI15y ago
Your Answer
Related Questions
Why does ETTR with digital prioritize highlights, unlike exposing negative film for the shadows?
Why don’t cameras offer an automatic ETTR metering mode for RAW?
How do camera metering modes use 18% gray in real scenes?
When should you expose to protect highlights versus brighten the exposure for cleaner shadows?
Does spot or partial metering treat the metered area as middle gray?