70D bad images

[etcalvert]

Occasionally I get distorted images when shooting with my 70D.  Below is an example of two shots taken a few minutes apart with same camera settings: Manual mode, 1/60, f5.6, iso800 and manual focus.  Can any one tell me what causes this sort of distortion?  The proble occurrs too often.

[ScottyP · Accepted solution]

Blown highlights. The brightest patch on that white dogwood petal was too bright for the camera to record so there is an area with essentially no information other than white. 

You can set the camera to show you colored pixels where you have blown highlights or their opposite, patches where it is so dark you are capturing nothing but black.   Just be aware when shooting something white with direct sun on it that you may be exceeding the camera's dynamic range. 

The fix is to use negative exposure compensation. You can dial in 1 stop and see if that is enough and adjust from there. Then in post processing you can boost exposure without boosting highlights to bring the rest of the shot up to proper brightness.

Another fix, if you have a larger bright patch, is to use the exposure lock on that bright patch, then recompose the shot. It will expose the shot so the bright patch is not blown, and then you adjust the rest of the shot in post as described above.  

Also, always shoot in RAW.  You have much more leeway to edit a file's exposure in RAW than in JPG. If you edit a JPG more than about a stop in exposure you may start to see weird patches like that where there just was not enough in the JPG file to work with. 

[ScottyP]

Another, perhaps easier way to deal with it is to use spot metering mode, instead of evaluative metering. That makes the camera take exposure readings based only on the very center of the frame. Provided you put the brightest area under the center AF point, centering the picture on that spot, that should do it for you. If you don't want to compose it with that in the very center, use exposure lock and recompose or use negative exposure compensation, both as per above. 

[Waddizzle]

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@ScottyP wrote:

Another, perhaps easier way to deal with it is to use spot metering mode, instead of evaluative metering. That makes the camera take exposure readings based only on the very center of the frame. Provided you put the brightest area under the center AF point, centering the picture on that spot, that should do it for you. If you don't want to compose it with that in the very center, use exposure lock and recompose or use negative exposure compensation, both as per above. 

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I saw your post, so I checked the EXIF data.  It was as I suspected, the photo was taken using spot metering, not evaluative metering.

[ScottyP]

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@Waddizzle wrote:

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@ScottyP wrote:

Another, perhaps easier way to deal with it is to use spot metering mode, instead of evaluative metering. That makes the camera take exposure readings based only on the very center of the frame. Provided you put the brightest area under the center AF point, centering the picture on that spot, that should do it for you. If you don't want to compose it with that in the very center, use exposure lock and recompose or use negative exposure compensation, both as per above. 

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I saw your post, so I checked the EXIF data.  It was as I suspected, the photo was taken using spot metering, not evaluative metering.

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I may have underestimated the evaluative metering setting. It is also possible he spot metered for the yellow center of the flower and that caused the white petals with the reflected sunlight to blow out?  I had specifird spot metering only works if the highlight is cratered in the image. If composition dictates otherwise then use exposure lock on the highlight and then recompose. 

[etcalvert]

thanks for the info. I did shoot in raw and jpg, but sent jpg because of size.

[utavsfan]

I'm having the same issue. But those lines actually print when I print my images. Sometimes I don't care that a portion is overexposed. But I'm going nuts editing the lines out of images 😉 Did your lines print on those images? Or was that just your camera's warning? thx.

[TCampbell]

Do you only see this after importing the images to the computer and, if so, what software are you using?

Both images are over-exposed, but the first image is heavily over-exposed.

Check your histogram.  You'll see the data runs off the right-edge of the histogram -- indicating that the exposure was lighting up pixels brighter than the maximum value that the camera can record.

Some software (and it's a built-in feature of the camera that you can optionally enable but isn't enabled by default) has the ability to show clipped areas of the image (over exposure or underexposure).  The "Highlight Alert" feature is sometimes referred to as the "blinkies" because on the camera image review it will causes any clipped pixels to blink when you are looking at the image.  That calls your attention to the fact that you should adjust exposure or change the lighting.

This *may* be what your software is showing you because the areas that have the shaded "linen" like grey texture happen to be the same areas where the image is blown out (over-exposed.)

If you back off the exposure, you should be fine.

[etcalvert]

Jpg is from camera.

[Waddizzle]

Yeah, the shots are overexposed.  Which metering mode are you using?  This type of exposure should not occur if use "Evalutative Metering".  In fact, I have found very few scearios to switch from "Evaluative Metering" mode.  Use a hood.

I like to photograph landscapes, cityscapes, and lots of flowers and other still life shots.  I am satisfied with the exposures that I get that I am gonig to say that I never change metering modes.  The times that I have, I was using a tripod to shoot a macro shot, which does not mean I always switch modes when shooting macros.