Histrogram

[u8myufo]

Ok I am trying to get into the habit of using this more, now whilst I have a grasp of what it shows and what I should be aiming for, am I right in thinking it is not just a simple matter of over or under exposing by however many stops to achieve the desired graph? If for example it is showing far to the left or right, is there a method for adjusting? I assume and I only assume cos I dont read much, that f/stop, shutter, iso, wb, and even which metering method used will all have some impact on how the graph will look. So is it down to the individual to decide what he needs to adjust for that particular shot and adjust accordingly? Or have I got it all wrong? I have found many links to explain about the histrogram but nothing on compensating for it, any help would be great.

 

[SealBeard]

Although I feel I understand in general what the Histogram shows/means and how to work with it, I would love to hear someone with lots more experience in the field answer this question, for my own understanding also

Bump.

 

[The Matt]

How do the pictures look? Histograms vary vastly depending on what you're photographing. You might want a scene with a histogram leaning way to one side. Depends very much on what you're photographing and how you want it exposed

 

[ChrisMClark]

I don't use histogram at all much anymore and just you my eyes on the image

 

[david1701]

the thing with looking at the hstogram is to make sure nothing falls off the edge

its to stop you blowing highlights and clipping blacks, you also get individual histograms for the colours so you can do the same for red blue and greens

you cann expose to the right and other clever things but I mainly use it to check that my well exposed shot has no blown or clipped shades

(you can also check that the distrobution of light looks good but that takes more getting used to)

 

[Terrywoodenpic]

Histograms count Pixels
It does this for each tone value it finds and shows them in the form of a graph.
The ones on the left shows the dark tones the ones on the right the bright tones.

There is no "correct Histogram"
If you photographed a small white bird against a black background. There would be a huge number of Dark pixels to count and display, virtually no middle tones and a few highlight tones.

The histogram would show a Huge spike on the left almost nothing across the middle and a small spike on the right. This would be the correct exposure and histogram for that particular subject.
When looking at a histogram you should think about what it is telling you in tone (pixel) terms.
If it agrees with the subject in front of you the exposure is correct.

What you will not normally want is for areas at each end that are cut off in their prime. These are areas that have exceeded the dynamic range of the sensor.

 

[u8myufo]

How do the pictures look? Histograms vary vastly depending on what you're photographing. You might want a scene with a histogram leaning way to one side. Depends very much on what you're photographing and how you want it exposed

Well most of my pics look ok but I am just trying to improve on them

I don't use histogram at all much anymore and just you my eyes on the image

Thats what I was doing, and although each to their own doing exactly that is the first mistake :rules:

the thing with looking at the hstogram is to make sure nothing falls off the edge

its to stop you blowing highlights and clipping blacks, you also get individual histograms for the colours so you can do the same for red blue and greens

you cann expose to the right and other clever things but I mainly use it to check that my well exposed shot has no blown or clipped shades

(you can also check that the distrobution of light looks good but that takes more getting used to)

Yeh I understand most of that, so I assume then that if shutter speed or f/stop was your main priority, you would compensate in other ways.

 

[Lewis101]

Ok I am trying to get into the habit of using this more, now whilst I have a grasp of what it shows and what I should be aiming for, am I right in thinking it is not just a simple matter of over or under exposing by however many stops to achieve the desired graph? If for example it is showing far to the left or right, is there a method for adjusting? I assume and I only assume cos I dont read much, that f/stop, shutter, iso, wb, and even which metering method used will all have some impact on how the graph will look. So is it down to the individual to decide what he needs to adjust for that particular shot and adjust accordingly? Or have I got it all wrong? I have found many links to explain about the histrogram but nothing on compensating for it, any help would be great.

Basically, when you view the histogram and find the image is being over or under exposed you then consider what adjustments to make with regards to the aperture, shutter speed or ISO. Which of these you adjust depends entirely on the circumstances and what you're trying to shoot.

For example, if you were trying to shoot birds in flight you would thus require a fairly fast shutter speed. If you then set your aperture to it's widest value, and then choose a reasonably fast shutter speed but found the shot being underexposed, you'd increase the ISO.

There are an infinite different number of circumstances you can find youself in when shooting. When trying to get a correct exposure, you need to consider the effects aperture, shutter speed and ISO will have on the shot. A wider aperture will provide you with a faster shutter speed, but reduces the depth of field which may be unsuitable for some shots. A fast shutter speed results in sharp shots, but may not be aesthetically pleasing for panning shots. For seascapes, a short shutter speed can be desirable (this is where filters come in). A higher ISO will provide you with a faster shutter speed, making hand-held shots easier, but will result in a noisier image.

For each shot, many different settings will result in the same exposure. You just need to decide which settings are right for the shot.

I hope this post is helpful as from what I wrote I was getting the idea that you understand what the histogram shows, just not what setting to adjust to gain a correct exposure.

 

[HoppyUK]

Ok I am trying to get into the habit of using this more, now whilst I have a grasp of what it shows and what I should be aiming for, am I right in thinking it is not just a simple matter of over or under exposing by however many stops to achieve the desired graph? If for example it is showing far to the left or right, is there a method for adjusting? I assume and I only assume cos I dont read much, that f/stop, shutter, iso, wb, and even which metering method used will all have some impact on how the graph will look. So is it down to the individual to decide what he needs to adjust for that particular shot and adjust accordingly? Or have I got it all wrong? I have found many links to explain about the histrogram but nothing on compensating for it, any help would be great.

I wonder if you are trying to over complicate things. You have almost got it right in your first sentence, because it is"just a simple matter of over or under exposing by however many stops to achieve the desired graph." That is all there is to it.

There are two components to exposure technique - metering for the correct level, and the settings used to achieve that level. There is only ever one level of optimum exposure, and it makes no difference how you arrive at it - clever metering options, experience or guesswork, it makes no difference.

You then have to deliver the optimum exposure level to the sensor with a combination of lens aperture, shutter speed and ISO options. Mix and match them how you like, so long as the level remains the same exposure will always be optimum (even though all sorts of other things may change, eg depth of field).

The histogram is just the best method yet devised to tell you exactly what exposure level you have actually got on the sensor. The main thing is to ensure that all important tones from light to dark are inside the two ends of the graph. The LCD image will give you a good steer on that, then check the histogram to make sure. The danger area is blown highlights and the first thing to do here is to enable 'blinkies' in custom functions - this will make over exposed highlights flash black and white on the LCD as a warning. If you then switch to the histogram, they will show as a spike butting straight up against the right hand edge.

This might be okay, or it might not. It depends whether the blown highlights are important or not as it's almost impossible to get them all in much of the time. If the sun is in shot for example, you'll never get that within the extremes of the histogram together with foregorund and shadow detail, it's impossible. So you have to decide where the cut off is going to be and you do that by adjusting the exposure level, usually with the +/- compensation dial, but by whatever method suits you.

Adding or substracting from the exposure simply slides the histogram graph right or left and it is up to you to decide where you want it. You can do nothing about the shape of the graph with exposure settings - that's decided by the subject and the lighting - only its position.

You will hear people talk about 'expose to the right' which is an advanced technique to get the last drop of quality into the image file, if you are going to post process it. Basically, there is a lot more image information recorded in the right hand end of the graph so the further you can push it that way, even if the LCD image looks too bright, the more data you will have to play with in post where you would just darken it back down again - the result is that you get more detail in the shadows.

However, the obvious danger in doing this is that you will blow the highlights and most people find that pulling up the shadows a bit in post processing is easier than trying to rescue blown highlights because once they're gone, they're gone for good.

I will just add that the histogram is derived from a JPEG image tagged to the Raw file. It is not actually the Raw image. Some people will say that therefore it in not an absolute guarantee of exposure level. I say don't listen to them

 

[BeccaF]

my theory is - fix it afterwards as long as its not too bad LO

 

[u8myufo]

Basically, when you view the histogram and find the image is being over or under exposed you then consider what adjustments to make with regards to the aperture, shutter speed or ISO. Which of these you adjust depends entirely on the circumstances and what you're trying to shoot.

For example, if you were trying to shoot birds in flight you would thus require a fairly fast shutter speed. If you then set your aperture to it's widest value, and then choose a reasonably fast shutter speed but found the shot being underexposed, you'd increase the ISO.

There are an infinite different number of circumstances you can find youself in when shooting. When trying to get a correct exposure, you need to consider the effects aperture, shutter speed and ISO will have on the shot. A wider aperture will provide you with a faster shutter speed, but reduces the depth of field which may be unsuitable for some shots. A fast shutter speed results in sharp shots, but may not be aesthetically pleasing for panning shots. For seascapes, a short shutter speed can be desirable (this is where filters come in). A higher ISO will provide you with a faster shutter speed, making hand-held shots easier, but will result in a noisier image.

For each shot, many different settings will result in the same exposure. You just need to decide which settings are right for the shot.

I hope this post is helpful as from what I wrote I was getting the idea that you understand what the histogram shows, just not what setting to adjust to gain a correct exposure.

Thanks Lewis

I wonder if you are trying to over complicate things. You have almost got it right in your first sentence, because it is"just a simple matter of over or under exposing by however many stops to achieve the desired graph." That is all there is to it.

There are two components to exposure technique - metering for the correct level, and the settings used to achieve that level. There is only ever one level of optimum exposure, and it makes no difference how you arrive at it - clever metering options, experience or guesswork, it makes no difference.

You then have to deliver the optimum exposure level to the sensor with a combination of lens aperture, shutter speed and ISO options. Mix and match them how you like, so long as the level remains the same exposure will always be optimum (even though all sorts of other things may change, eg depth of field).

The histogram is just the best method yet devised to tell you exactly what exposure level you have actually got on the sensor. The main thing is to ensure that all important tones from light to dark are inside the two ends of the graph. The LCD image will give you a good steer on that, then check the histogram to make sure. The danger area is blown highlights and the first thing to do here is to enable 'blinkies' in custom functions - this will make over exposed highlights flash black and white on the LCD as a warning. If you then switch to the histogram, they will show as a spike butting straight up against the right hand edge.

This might be okay, or it might not. It depends whether the blown highlights are important or not as it's almost impossible to get them all in much of the time. If the sun is in shot for example, you'll never get that within the extremes of the histogram together with foregorund and shadow detail, it's impossible. So you have to decide where the cut off is going to be and you do that by adjusting the exposure level, usually with the +/- compensation dial, but by whatever method suits you.

Adding or substracting from the exposure simply slides the histogram graph right or left and it is up to you to decide where you want it. You can do nothing about the shape of the graph with exposure settings - that's decided by the subject and the lighting - only its position.

You will hear people talk about 'expose to the right' which is an advanced technique to get the last drop of quality into the image file, if you are going to post process it. Basically, there is a lot more image information recorded in the right hand end of the graph so the further you can push it that way, even if the LCD image looks too bright, the more data you will have to play with in post where you would just darken it back down again - the result is that you get more detail in the shadows.

However, the obvious danger in doing this is that you will blow the highlights and most people find that pulling up the shadows a bit in post processing is easier than trying to rescue blown highlights because once they're gone, they're gone for good.

I will just add that the histogram is derived from a JPEG image tagged to the Raw file. It is not actually the Raw image. Some people will say that therefore it in not an absolute guarantee of exposure level. I say don't listen to them

And thank you Hoppy, you are probably right about me over complicating things and kinda confirm what I was suspecting that it is indeed down to each individual shot most of the time. Well I have had some informative replies which will now let me sleep at night
Cheers Guy`s