Why does my Canon 70D mis-expose high-contrast scenes in P mode?
Asked 5/26/2019
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2 answers
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I often get photos that look overexposed or underexposed with my Canon 70D, especially in scenes with bright highlights and deep shadows. These examples were shot in P mode, RAW, evaluative metering, Auto ISO, and minimum shutter speed 1/125. I converted the RAW files in Canon Digital Photo Professional, and the JPEGs look very similar in exposure to the originals. I'm using a Tamron 24-70mm f/2.8 G2 with the hood attached. Is this likely a camera/settings issue, or just difficult lighting? What can I do to get more consistent exposure?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
7y ago
2 Answers
19
All of these scenes have something in common: they’re high contrast with many, many stops between the shadows and the highlights.
If you were to meter for the shadows, then you’d blow the highlights (image 3). Meter for the highlights, and drown the shadows (images 1 and 2).
Because you set evaluative metering, the whole frame is being taken into account for the metering. I’m sure it’s more technical, but it appears the camera is simply favoring the side (highlight or shadow) that simply exists more in the frame in order to maximize the amount of decent exposure area.
Obviously, this leaves much to be desired. But, high contrast scenes are where auto modes go to die. This is where you should be the one making the exposure decisions.
Use spot metering on the shadows and highlights to get an idea how far apart they are. Use this knowledge to pick the exposure you want that will sacrifice the detail you’re willing to give up. Want all of the detail? Shoot an HDR shot.
My camera has a partial metering setting, which is something in between of evaluative and spot, I think I might try using it for a bit and see the results
While switching to partial may improve results on a subject - it won’t really help in these scenes. You have such a drastic difference in light and dark that you’ve gone outside of the camera’s dynamic range.
Image 2’s best bet to get the scene in camera would be to use a grad. ND filter. Images 1 and 3 would need multiple exposures combined in post to capture the whole range. (Upon looking at them further, a grad. ND would have been of use in all of the images., though image 2 is the most stereotypical use case)
This is why your camera fails to produce results you like in these scenes: it doesn’t know what you want. YOU need to tell it the exact exposure and KNOW your gear well enough to know that you’re going to sacrifice some shadow detail and/or blow some highlights based on your chosen exposure.
I highly recommend getting very familiar with the histogram and how to use it along with the Zone System. It’s a concept from way back in the day but in a nutshell: shoot the exposure that gets the details that you want. It may not be print worthy straight from the camera, but if it’s got everything you need, you can finish perfecting in post. (Film guys, I know that that is a gross simplification. Not trying to explain it here, simply wet OP’s appetite to learn).
Originally by user67377. Source · Licensed CC BY-SA 4.0
user67377
7y ago
0
Generated from our catalog & community — verify before relying on it.
This is most likely normal behavior in very high-contrast scenes, not a fault with the camera or lens. Evaluative metering tries to balance the whole frame, but when a scene contains both very bright highlights and deep shadows, there may be no single exposure that preserves both.
In these situations, auto modes like P can struggle. The camera will often bias exposure toward whichever tones occupy more of the frame, leaving either shadows too dark or highlights blown.
What to do:
- Use exposure compensation when shooting in automatic modes.
- In high-contrast scenes, it’s usually safer to expose slightly darker to protect highlights, since blown highlights are often unrecoverable while shadows can often be lifted in RAW processing.
- Consider spot metering important areas instead of evaluative metering.
- For extreme contrast, bracket exposures and combine them later (HDR) if needed.
So the issue is mainly the lighting and metering choice, not your 70D itself.
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UniqueBot
AI7y ago
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