using the histogram for proper exposure

[Kbarredo]

So I know how to check for proper exposure using histograms on my camera. I was wondering what if the camera is tricked due to the amount of black objects or white objects. For example a photo is predominately black with a certain part filled in with flash. Like my profile picture for example. It says it is underexposed due to all the black around me. Or how about a snow picture where its mostly white and the histogram spikes on the right side of the graph. Do i stop trusting the histogram then and just trust the camera meter and self preference?

 

[analog.universe]

The histogram is generally pretty accurate, except at the very edges of the graph, I find. This probably varies from camera to camera, but I've noticed I can get about a half stop over exposed before the histogram pegs on the right side.

But essentially, the histogram plots brightness on the X axis, and pixel count on the Y. So if you had a shot that was mostly black, with a subject lit by flash, you'd see a lot of pixels on the left side, and then a few spikes on the right where your subject is. If that picture was underexposed, your subject spikes wouldn't be on the right, if it was over exposed, they'd touch the right side of the graph. A picture of snow should pretty much only occupy the right side of the graph, without touching the boundary.

For the type of shots I take, I find the actual meter in the camera is most useful to me when in spot mode. In the simplest scenario, I point it at the brightest part of the scene to make sure I'm not over, and the darkest part to make sure I'm not under, and then check the histogram afterwards. I'm a big fan of "expose to the right" (google it), so if I've got room to push the histogram to the right I will.

 

[KenC]

You can trust the histogram up to a point. It is possible to have small areas that are blown out and thus beyond the right edge, but the rest of the histogram is well within the lines, without being jammed up against the right. I usually rely more on looking for flashing areas on the image, which at least in the Canon system indicate overexposure (other cameras may have a different method). Of course a very small area would be hard to see, but if it's small enough it may not be a problem.

 

[Robin Usagani]

dont use the histogram.. use highlight warning thing. You want to overexpose it as high as possible before it is starting to lose data.

 

[kundalini]

Another vote for using the highlight warning.

I liken it to glancing at an analogue clock (highlights) to know the time as opposed to having to read a digital clock (histogram). In bright conditions I can't always read the LCD (histogram), but the blinkies will still stand out (highlights).

 

[Dao]

I think this article is quite good for explaining how to use histogram wisely.

Juza Nature Photography - Exposure and histogram

 

[Kbarredo]

I was also thinking of using a grey card for proper exposure. What's the down side of this method

 

[pgriz]

Thanks, Dao, for the link - lots of very good information there.

 

[Robin Usagani]

I was also thinking of using a grey card for proper exposure. What's the down side of this method

? I dont understand your question. Your flash still fires after you meter. So your metering is not counting the flash.

EDIT:
I got confused with your other thread. Exposing using a grey card is usually good until you are adding flash into the equation.

 

[Kbarredo]

I was also thinking of using a grey card for proper exposure. What's the down side of this method

? I dont understand your question. Your flash still fires after you meter. So your metering is not counting the flash.EDIT:I got confused with your other thread. Exposing using a grey card is usually good until you are adding flash into the equation.

Lol yeah I do that sometimes too. I'm more worried about ambient light from the sun blowing my photo out and causing hot spots.

 

[kundalini]

I was also thinking of using a grey card for proper exposure. What's the down side of this method

Please be kind to TPF members and make an effort to use the Search function.

 

[Robin Usagani]

I am really confused. I thought you had a lot of experience already? Why are you asking these basic questions?

 

[Kbarredo]

I am really confused. I thought you had a lot of experience already? Why are you asking these basic questions?

because when my camera meter says its properly exposed it says under exposed on the histogram. So I'm not sure what to trust. Then I just found out you can use grey cards for proper exposure. I'm just trying to lessen my pping and get it right on the camera.

 

[subscuck]

because when my camera meter says its properly exposed it says under exposed on the histogram.

Is it really underexposed or is it simply showing the tonal range in your photo? If the image you've captured is predominately shadows and mid tones, your histogram will be mostly to the left and center. This doesn't mean it's underexposed, it simply means that's the tonal range of your shot, and therefore it's properly exposed. The only time your histogram will be uniform from left to right is if you have a uniform distribution of shadows, mids and highlights.

You have to evaluate the scene you're shooting in terms of mids, shadows and highlights, and correlate that with what your histogram is showing you.

 

[Robin Usagani]

You need to learn spot metering and zoning system. Most of the time any metering system will be off. The only one you can trust is spot metering ONLY if you know what you are doing and you point it at the right place. You dont want to always put your light meter at 0 either. For example if I am shooting a bride in the sun, I would point at the brightest spot on her dress with spot meter and set it at +1 2/3. It depends in situation. I never use spot metering with semi auto mode though (aperture or speed priority).