Why doesn't Manual mode match the exposure I saw in Auto mode with the same settings?
Asked 9/20/2017
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2 answers
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In low light, I sometimes switch my camera to Auto to see what settings it chooses, then try to copy those settings in Manual as a starting point. But the photo often looks different even when I use the same aperture, shutter speed, and ISO values.
For example, I took one shot in Manual and one in Auto. Both appeared to be f/4, 1/60s, ISO 400, with flash set to automatic, but the results did not match.
Why can’t I reliably reproduce the same result in Manual mode when the displayed settings look identical? What camera settings should I check?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
8y ago
2 Answers
1
Look in your images EXIF data to make sure the ISO was 400 in both when they were exposed. It doesn't look like it was. EXIF shows the settings actually used.
Auto mode uses Auto ISO, Auto White Balance, and it controls color profile too. Auto mode is Auto everything. But you don't set ISO to anything in Auto, Auto does what it wants to do. Your ISO setting might say 400, but Auto does what it wants. EXIF will show that.
In contrast, A,S,P,M are just exposure modes.
These modes do not use Auto ISO or Auto WB unless you configure them individually to be on. Default is off. You set color profile yourself too. And you turn the flash on if you want flash to be used.
Instead of using Auto mode for these comparisons, use Aperture mode A. A,S,P are auto Exposure, but then Auto ISO and Auto WB will be same as Manual, only on if you have selected them On. Auto ISO and Auto WB can have effect if they are on. But only Exposure should vary in A and M mode, and Manual can duplicate what A mode does.
But Auto mode is a whole different game, fully automatic, no manual control.
Originally by user38978. Source · Licensed CC BY-SA 4.0
user38978
8y ago
0
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Because full Auto usually changes more than just aperture, shutter speed, and ISO. It may also use auto ISO, auto white balance, different picture/color settings, and different flash behavior. So even if the screen seems to show f/4, 1/60s, and ISO 400, the camera may not have actually used the same values or flash output in both shots.
First, check the EXIF data from both images to see the settings actually used. That will confirm whether ISO 400 was really used for both exposures.
Also note that full Auto mode is not the same as P/A/S/M modes. In Auto, the camera may override or adjust settings to get what it thinks is a proper exposure. Flash operation can differ too, especially if flash exposure compensation is set in Manual mode.
A better comparison is to use Aperture Priority, Shutter Priority, or Program mode rather than full Auto. Those modes still automate exposure, but are more predictable, and any Auto ISO or Auto WB behavior can usually be enabled or disabled separately.
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