# Overexposing



## Jethro (Nov 13, 2011)

Hey guys. So I have this little problem and I hoped you may give me some advices on how to improve and stop making this mistake 

My problem is that I tend to overexpose pictures. When I shoot I always take a shot of the scene several times with different setting (f.e. different times - 1/800, 1/1000, 1/1600) so luckily there is always one that is exposed okay and if not, I can correct it in the Photoshop since I shoot in RAW. Though I would like to stop overexposing so much. The problem is, pictures always look darker on the camera than they are on the PC, so when I look at a picture on the camera it looks okay. I tried to keep in mind that camera screen makes things darker and adjust the settings to this, but then the tendence flipped to underexposing..

Do you have any tips, tricks and other stuff that helps you expose correctly? I know it is not THAT much of a deal since most of the times it can be corrected in the post-proccesing, but I would like to learn to expose correctly without Photoshop.

Oh, and I shoot with Canon 7D, 50mm/1.8 II and Sigma 17-7-/2.8-4


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## dxqcanada (Nov 13, 2011)

Question is ... is the Camera LCD too dark ... is your computer screen too bright ... is the camera exposure meter faulty ... are you metering the scene incorrectly ?


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## dxqcanada (Nov 13, 2011)

I will have to add that my camera tends to over expose (the meter is reading scenes darker than what it actually is) ... so I have set my exposure compensation to offset it.


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## SGorman (Nov 13, 2011)

Have you tried spot metering? Also, SLRs have histograms that you can turn on and see the hot spots on the LCD, so you can correct the problem rather than fill up your card with extra shots. 

*edit duh, read fail on my part. Your camera (7d) can do both.  Also you have Highlight alert in your menu.  If you enable that you can see the problems.

If you shoot in RAW you can fix some of it in Digital Photo Professional.


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## unpopular (Nov 13, 2011)

There is a difference between "over exposure" and "too light". Too light is an aesthetic issue, over exposure is a technical issue resulting in lost data.

Many photographer, myself included, believe that the roll of exposure is to gather as much detail from the scene as possible but increasing exposure to the absolute limit without "clipping". Provided you don't have blown hilights, what you see as over exposure is a good thing in order to prevent noisey artifacts - cameras measure light, not the lack of light, so more light means more signal and less noise.

However, if you are clipping over exposure is always going to be a bad thing.

As Gorman points out using warnings like this "hilight alert" is a good idea. I would go a step further and use any built-in histogram options you'd have. You simply cannot ever rely on what the on-camera screen is telling you, this isn't meant to be a calibrated monitor. Instead, you want to go by the numbers of the file itself.

One way to always avoid these surprises is to learn and use your spot meter in manual mode. Spot metering permits you to actively decide what tonal region is exposed how and how other tonal regions will be affected by choices you make.


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## SGorman (Nov 13, 2011)

To add, when you spot meter you are looking at what you want exposed correctly.  Just as an example, here's a snapshot of my daughter, not meant to be anything special, but it illustrates what spot metering does.  This was taken in harsh sunlight source over and behind her, so I spot metered only her face, which would normally end up underexposed if you leave the metering up to the camera, because the camera will see that mound in front of her and your meter for that, when it isn't what you want.  Telling the camera what you want to meter solves a lot of these problems.  Obviously there are some hot spots from the direct sunlight in her hair, mound is a bit hot, but sometimes you have to let that stuff go to get the exposure where you want it.   





MiaBallfield by gormanimagery, on Flickr


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## unpopular (Nov 13, 2011)

Nice shot Gorman! This is a particularly tricky situation - though I think there is something you've missed re. spot metering.

Your daughter has a darker skin tone, which permits the proper exposure without compensation. If she were very fair-skinned, her face would have been under exposed. My bet is also if you were closer she would have under exposed and her hair also influenced the meter.

You may already know this, so I am more writing to the OP here. It's not quite as simple as pointing at "what you want to be properly exposed". The camera only knows about how much light is being reflected into the lens, and does not know anything about what light is available, and the meter is calibrated only to a specific value - that which reflects as much as it absorbs - the so called "Middle Grey".

So when you dial in "0" with a spot meter, everything within the spot will be equal in luminance to this "middle grey" - in a perfectly calibrated world, anyway.

Because the lightest region where I'd want significant detail would be the sand, I'd be inclined to meter off it and provide 3-4 or more stops greater exposure, and then apply a curve in post. 

If this were posed and I were awesome, I'd meter directly off the specular highlight in her leg and provide 4 2/3 more exposure - placing it on the outer limits of my camera - and compare against her face and the background to visualize the results.

Of course, it's just a snapshot and I'm not awesome, so I don't mean this as any kind of criticism - just more "ideal world" kind of thing. In practice, this is probobly the best case for this scenario, and no matter where you meter from or how you compensate that reading, you'd get similar results so not to block up her face at the expense of highlight detail elsewhere.

I'll post an in depth article on spot metering in a few days. I've also posted a lot here:

http://www.thephotoforum.com/forum/...oto-gallery/262171-spot-metering-how-use.html


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## SGorman (Nov 13, 2011)

That was my point, just not explained as well.  Yes, if I wanted to make sure the highlights weren't blown out, that is where I would have metered.  In my mind it's simple because much of how I've learned so far was trial and error, but I'm not always able to tell you why.


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## unpopular (Nov 13, 2011)

^^ so just curious, did you adjust the exposure when you metered off your daughter, or did ±0EV work out?


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## SGorman (Nov 13, 2011)

Yes, I adjusted the exposure when I metered off of her face, in this case, just shutterspeed. I didn't use exposure compensation.


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## unpopular (Nov 13, 2011)

Then you were using Tv?


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## SGorman (Nov 13, 2011)

No, M.


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## Kimbalina81 (Nov 14, 2011)

I tend to do this, too.  Is there a way to fix blown out images post processing?


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## cgipson1 (Nov 14, 2011)

Kimbalina81 said:


> I tend to do this, too.  Is there a way to fix blown out images post processing?



Blown out.. usually means a total loss of detail in the "blown out" area.. so there is nothing there to "fix". If you shoot Raw..  sometimes you can pull some detail out of a blown out area, it depends on how much detail was recorded. But if there is no detail (solid white).. then you are out of luck. You can try cloning in some detail from nearby regions in the photos that would match the blown out area... takes a little practice to make it look good, but it can be done.


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## MLeeK (Nov 14, 2011)

Reading the histogram will save your ass along with the highlight warnings. The key is to know what your histogram should look like. The image posted should be very much to the dark side of the histogram while the highlight warnings should only be blinking on the white of her shirt and possible some of the crown of her head. 

The cameras highlight warning system will warn you if there is a blow out or complete loss of ONE color channel. You may have a highlight warning on something that is purely one color because the other colors are missing. 

It also helps if you understand your meter and have a good working relationship with it. This may seem silly and like I am talking to a child or it may not... 
MANY of us don't realize that the meter is stupid as hell. It knows NOTHING about the scene you are shooting. The only thing the meter knows is that it is supposed to make the exposure say 0 based on the metering mode you are using and the light coming in the lens. 0 to the meter is roughly somewhere between 12% and 18% gray on the light to dark scale. 
	

	
	
		
		

		
			





If you are using evaluative metering it's trying to make the whole scene that bright on average

If you are using center weighted average metering it's averaging the whole scene to that brighness, but making what is in the center more important in the average. Like a weighted test.

If you are shooting  spot metering it is trying to make whatever is in the spot average out to that brightness. 

I find that when shooting outside grass is often a good thing to meter off of and to set your exposure just slightly brighter than 0 in the case of a portrait.


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## unpopular (Nov 14, 2011)

^^ what exactly do they mean by 12% or 18%? 18% or 12% of what, and what is 100% or 0%?

I'm guessing this is something left over from densitometers and film, right? Or percentage on a logarithmic scale, maybe? If you dial in 18% of black in your favorite imaging app, you'll get a very dark shade. So what's up with this "middle grey" at "18%"?

This is teh one thing that always confused me.


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## MLeeK (Nov 14, 2011)

12 to 18% of LIGHT/Dark. 100% is pure black and 0% is white. Why is that so difficult to understand. 12-18% on the scale from light to dark... Not color, LIGHT.


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## MReid (Nov 14, 2011)

Adjust the brightness on your screen, set up your blinkies to tell you when highlights are blown. Learn to shoot in Aperture priority and use the exposure compension dial.....are you messing with us ???


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## clanthar (Nov 14, 2011)

unpopular said:


> ^^ what exactly do they mean by 12% or 18%? 18% or 12% of what, and what is 100% or 0%?
> 
> I'm guessing this is something left over from densitometers and film, right? Or percentage on a logarithmic scale, maybe? If you dial in 18% of black in your favorite imaging app, you'll get a very dark shade. So what's up with this "middle grey" at "18%"?
> 
> This is teh one thing that always confused me.



18% reflectance. A grey card reflects back 18% of the light that strikes it.

Joe


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## unpopular (Nov 14, 2011)

Ok. 

But why then does 18% reflectance relate to 50% transmission on film, or level 128 in 8-bit? Why doesn't 18% reflectance = 18% density? Why does it render as "middle grey"? Is it just how our eyes see things, or is this one of those logarithmic scale things that always confuses me so much?


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## Mike_E (Jun 17, 2014)

DIY: Making Your Own Gray Cards - DIY Photography

Instead if 82% substitute 88% brightness.  An 8.5 X 11 inch matte photo sheet works best.


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## coffeefilter (Jun 17, 2014)

MLeeK said:


> Why is that so difficult to understand. 12-18% on the scale from light to dark... Not color, LIGHT.



Chill out. No need to get up in arms over a question about what 18% gray means.


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## WayneF (Jun 17, 2014)

unpopular said:


> Ok.
> 
> But why then does 18% reflectance relate to 50% transmission on film, or level 128 in 8-bit? Why doesn't 18% reflectance = 18% density? Why does it render as "middle grey"? Is it just how our eyes see things, or is this one of those logarithmic scale things that always confuses me so much?




This one is a can of worms, but of course you are right, 18% is obviously 18%.   It is NOT 50%.

However, the quirk of the human eye/brain is that our eyes response is logarithmic, not linear, and our brain does think we perceive 18% as being about middle gray.  That is the only thing "middle" about 18%.

In the past ages, printing press printers calibrated their ink flow so that an 18% half tone test pattern printed to look to be about middle gray to the eye.

Ansel Adams had the notion that his middle Zone V ought to be 18% too. Eyes might see it that way (Ansel did this in the 1930s, with film only, and surely he never saw a digital histogram).  So he called 18% to be 50%, and we were sort of stuck with it.   But reflective light meters today are calibrated to 12.5%.  Ansel's was not a big error, we always tweak things anyway.

Anyway, we humans got confused (can't keep one concept of middle separate from another concept of middle), and when digital came along, and histograms had an apparent middle point.  So we continued to imagine 18% (analog) ought to be about mid point of a (digital) histogram.   18% ought to be 18% of course, and of course it is, in linear data (like Raw data).

But we don't see raw data, we see RGB data.  All of our RGB images are gamma encoded (data in the histogram too), and then when gamma encoded, 18% comes out at 117, which is about 46%.  Which is close enough to middle, so we imagined our dumb 50% midpoint notion was correct, when of course other factors we didn't understand were the only cause that 18% appeared there.   But the actual 50% point is gamma encoded to be up around 183, or about 73% (in a gamma histogram).

As very easy and obvious proof to see this:

If you tweak the exposure of something bright or white, so that the right end of histogram data aligns very near 255...
and then underexpose exactly one stop (which we know is 50%), it will not move anywhere near 128 at histogram middle.
It will be closer to 3/4 scale.  It won't be exactly 73% because the camera is shifting data to do white balance and contrast and stuff, hard to predict, but one stop down will be near 3/4 scale (not 50%), which is of course where 50% ought to be in the gamma histogram.

No one ever wants to know actual details however, so most ignore this, and continue thinking the midpoint of our (gamma) histogram is 50%.   Which is quite wrong, they cannot explain why that could be true, but it really doesn't matter what we think 50% is...  whatever happens happens anyway.


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## SCraig (Jun 17, 2014)

You guys know that you're responding to 2-1/2-year-old questions, right?


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## coffeefilter (Jun 17, 2014)

SCraig said:


> You guys know that you're responding to 2-1/2-year-old questions, right?



:blushing: Now I do.


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## WayneF (Jun 17, 2014)

LOL.   No, but it is still a good question.


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