How is this possible? Please comment.

pwm2 wrote in post #16254543
The sky seem to have similar exposure in both shots - it's just the church that is way different.

That would indicate the sun - changes to camera settings (automatic or manual) should have made a huge difference to the clouds too.

It really doesn't take many seconds for the sun to drastically change the conditions on a partly cloudy day.

Exactly, and I saw that on my last senior shoot. Just the wispiest of clouds that covered the sun yielded much better results than when the sun was blasting away with nothing to diffuse it. Too many of the shots were less than stellar that day...

Ive sent the images off to Canon support to get an idea of what could have happened. My camera is my baby,goes where I go,always at the ready. I love my camera and if theres something wrong I want to have it addressed. As soon as I find out what they say I will let everybody know.

I am really sure you are going to get the same answers, the only difference is that the objects in the foreground are very lit in one, and they go dark in the next, but the rest of the frame is pretty similar. I know of nothing that could go wrong in a camera to produce that effect.

Note that the eyes are extremely quick at changing their light sensitivity. Besides changing the pupil size, they can also chemically adjust their sensitivity. And that is a very, very quick reaction.

This means that when the sun changes, you can still look at the building and perceive similar light levels. Then you look back at the clouds and your eyes instantly adapt so you perceive similar light levels there too.

The camera is no where near able to match that performance. So it sees the sky with similar exposure on both photos, but will have an exposure setting for the complete image, which means the building will show a large difference.

It really is very deceptive that our eyes dynamically change their light sensitivity as you change spot to look at. This makes you see in real life a view that is completely different from what the camera catches - all because the camera has the same exposure used for sky and building, while your eye changes "exposure" depending on if you look at sky or building.

In short - you can totally miss several stops of changes in overall light levels unless you have a clear reference to compare with. So we see strong differences between shadow and light when an object casts a shadow. But we do not see the strong differences when everything has changed between shadow and light. And the tricky things with clouds is that they sometimes allows the sun to get hidden smoothly, and sometimes there are a visible edge between light and shadow.

I'm no expert but on the correctly exposed photo there are shadows on the building. That would
be just behind the two toned pickup truck on the right side as viewed. Takes light to make a shadow
camera won't do that.

Assuming as you said, the camera was on manual and the settings were identical, I'm gonna go with the sunlight changing. Just a moment when the cloud layer thinned out and let the sun through was enough to expose the buildings and trees properly. The sky in the background didn't change much. What little change there is I would think would be a change in white balance because of the direct sunlight.

I just downloaded the images and lifted the dark shot. It does not show a shadow under the window that is just above the trees. The original lighter shot has a strong shadow there. Looks like the light changed.

And a crop of the original lighter shot.

Well I actually checked the EXIF on the images as linked at Flicker. Bar the EXIF hijack hypothesis, and the times are different so probably not, although apparently shot at 3:18 AM. Both images were shot in Manual exposure mode, 1/1600s, f=7.1, ISO 100, Evaluative metering using a 60D with 24-105 L set at 35 mm focal length

I have both images open in separate tabs of my browser and switching between them shows that the tone of the blue sky in each is identical as is the apparent brightness of all of the clouds. The ONLY thing that could account for the difference in exposure of the church is a change in the level of illumination of the church. There was after all a difference of 12 seconds between the two shots. From the brighter image a copy and paste from EXIF viewer: Date and Time (Digitized) 2013:08:22 03:18:34 and from the darker: Date and Time (Digitized) 2013:08:22 03:18:46 so in the 12 seconds between them the sun went in behind a cloud. IT IS THE ONLY POSSIBLE ANSWER.

Alan

(So much for those who proclaim "I always shoot in manual" )
With ISO, aperture and shutter set, the only thing left is the scene illumination,. Camera is fine

Checking the Exif, the only other difference between the shots is Color Temperature. Not enough to justify the difference in the photos but probably an indication of the sun hiding behind a cloud.

One effect that I notice looking at these images presented one above the other and looking at the whole images. The blue sky/clouds appeare to be a bit brighter in the image with the under exposed church. However when I had them loaded into different tabs in Chrome and switched between them with just the sky displayed on screen then there is zero perceptual difference between the image brightness. I did not bother downloading them to check in PS but I reckon there will be no statistically significance in RGB values in comparable areas of the sky. I think it is interesting how the significant difference in the brightness of the bottom half of the imagr affects the perception of the brightness of the top half.

Alan

pwm2 wrote in post #16254629
Note that the eyes are extremely quick at changing their light sensitivity. Besides changing the pupil size, they can also chemically adjust their sensitivity. And that is a very, very quick reaction.

This means that when the sun changes, you can still look at the building and perceive similar light levels. Then you look back at the clouds and your eyes instantly adapt so you perceive similar light levels there too.

The camera is no where near able to match that performance. So it sees the sky with similar exposure on both photos, but will have an exposure setting for the complete image, which means the building will show a large difference.

It really is very deceptive that our eyes dynamically change their light sensitivity as you change spot to look at. This makes you see in real life a view that is completely different from what the camera catches - all because the camera has the same exposure used for sky and building, while your eye changes "exposure" depending on if you look at sky or building.

In short - you can totally miss several stops of changes in overall light levels unless you have a clear reference to compare with. So we see strong differences between shadow and light when an object casts a shadow. But we do not see the strong differences when everything has changed between shadow and light. And the tricky things with clouds is that they sometimes allows the sun to get hidden smoothly, and sometimes there are a visible edge between light and shadow.

Off topic a bit but I believe it is the brain that is most responsible for what you are describing. The image quality from our eyes is technically a bit less than what we think we are seeing. Our brains work some amazing magic interpolating, interpreting and heavily manipulating the two image streams coming in.

As frustrating as it seems in tough lighting, a still camera captures a much more accurate representation of a scene. What we 'see' is heavily polluted by what our subconscious thinks we should be seeing

So,I have read through all of the responses,and my first response is a super thanks to all who responded! But a special thanks to the guys who really went the extra mile to understand and interpret my delima.

Having the pics stacked to look at them at the same time makes a big differance. I looked closely at the area around the back of the truck - specifically the shadows cast on the wall. The shadows are clearly defined in the brighter exposed shot. But the other has no shadow in this area. After I saw this in Kim Johnsons and Gobeatys observations above I went and looked at the shots in DPP closer and after studying the shadows,have decided it must be that the sun poked through the clouds at just 'that' moment and in 'that' area and made the differeance in the 2 shots. Almost as if a beam of sun light broke through and hit the church. Kinda odd to me,but very likely/possible.

But having experienced this I will pay super close attention from now on on how these images are captured,my surroundings,lighting and so on. So thanks for the insite fellas and all the help!!

We could have ended all this debate back at reply #15

Your scenario might have been a good use for auto-ISO even though you were in manual mode.