05-21-2018 12:33 PM
Full auto mode (the green box) locks out many changes that would be permitted in other modes... one of which is exposure compensation. If you had dialed in exposure compensation in another mode, it would be ignored when you switch to auto mode.
I do not own an 80D but I have compared the reflected meter readings with my various Canon bodies against what my dedicated Sekonic meter reads and have found them to all be very accurate.
1 photographic stop represents a doubling or halving of the amount of light. If you have to dial the exposusre down by 3 stops, then that means you have to dial it down to 1/2 of 1/2 of 1/2 (or 1/8th) of the exposure that the camera wants to use. That's a huge difference.
You can test the camera on a bright sunny day.
In mid-day sunshine, the sun pumps out a very reliable amount of light. A correct exposure for the Sun based on the "Sunny 16" rule says that that IF (and only if) you use f/16, then the shutter speed should be the INVERSE of the ISO setting.
In other words if you use manual exposure, set your aperture to f/16, set your ISO to 100, then the shutter speed should be 1/100th sec. And in doing that... if you "meter" the scene with those settings dialed in, the built-in meter should show the digital needle near the center point.
CAVEAT: Keep in mind this is a "reflected" light meter. If you point the camera at a scene which is dominated by darks, the meter will read less light being reflected (because darks don't reflect as much) and the camera may indicate an under-exposure to encourage you to boost the exposure a bit. Conversely if you point the camera at a scene dominated by light colors, the opposite can happen. In other words, if the camera metering differs by a small amount (maybe a 1/3 of a stop) then I wouldn't worry too much. But if it differs by 3 stops (which is what you are saying seems to be happening) then that's a defect and needs to be addressed.
There are a few other issues you could check but I think are unlikely... I had wondered if the aperutre blades on your lens were stopping down as they should. You can dial in a high f-stop value then look at the front of your lens and press your depth-of-field preview button and make sure you see the aperture blades constrict.
You aren't using any filters on the front of the lens? I can only imagine that would result in the camera under-exposing but you are saying it is over-exposing so I doubt it's that.
Are you using "Evaluative" metering or some other mode such as "Spot" or "Center weighted", etc.?
I was using "Evaluative" metering. The "Sunny 16 Rule" turned out to be correct on the camera. I guess my biggest problem is that this camera is nothing like my Pentax that I used for years. I will keep experimenting with the metering. Thanks for your insight.
10-30-2019 08:18 PM
If experiencing overexposure in auto mode (greenbox dial mode), it is likely an issue of metering sensor, which located near the view finder. I have had such issue and resolved it:
Hope this helps.
08-14-2020 04:40 PM
Did you ever get this issue resolved? I bought a Canon EOS800D last year and have the exact same issue. As a total amateur, I used an 1100D for several years on the various auto settings and got lovely shots. With this one the auto settings are awful: over exposed and sometimes just blurry, with no apparent focus on anything. The plus side is that I have since learnt how to use the manual settings and made an effort to learn about photography. If I work really hard, I can get some decent shots using AV and TV, but like you, I almost always have to dial down the exposure. It would be great to be able to use auto sometimes, as when photographing the kids in particular, by the time I have set the camera up I have missed the shot!
08-14-2020 09:55 PM
The issue has not been resolved. Like you, I have an old camera, a Pentax K200D which takes much better images than my 80D. That being said the 80D has a whole host of other disappointing features connected to "exposure". The aperture priority setting in the time lapse feature does not work. It apparently is not designed to. I also have a heck of a time getting "tack sharp" images or even decently sharp images. I have about given up on that camera. For the price my phone does a better job. Just as something to try..... If you ever mount your 80D on a tripod try "masking", covering the eye piece with a piece of black tape and compare shots. It's very interesting and slightly scarry. I also do not understand the difference in manual mode when you switch between eye piece and "live veiw" the exposure setting is compleatly different, same scene different settings. Go figure?