Metering Modes Explained

We're going to start with the basics of exposure. Your camera is pre-programmed to assume that every photo that you take should be of an "average tone". The word "tone" confuses some people, but it just means a shade of color. So, light blue and light purple would be the same tone as would dark blue and dark purple. Get it?

The reason your camera makes that "average tone" assumption is pretty simple -it isn't smart enough to know what's in front of it. How can a camera tell if it's pointed at a white wall with dim light hitting it or a gray wall with really bright light hitting it? The answer is -it doesn't. It will assume that the wall is an "average tone" and your photo will come out an average gray tone either way.

Once you understand the camera's assumption you can use it to your advantage by anticipating and correcting for the camera's mistakes in judgement about a scene.

Let's pretend that this is the scene in front of you:


This is a pretty typical photo, so the camera's default metering should get it right. But, we're going to walk through exactly how the camera makes the decision of what the level of brightness should be for this scene to get a feel for how it works in more challenging photography situations.

"Evaluative" or "matrix" metering:
When you have your metering set to "scene", "matrix", or "evaluative" mode (they all mean the same thing, but different camera makers use different terms) what the camera does is it takes a look at the entire scene, averages it out, and decides on the correct brightness for the entire photo. For typical photos like the one above this default mode works very well since the majority of the photo is made up of colors of an "average" tone. But if the scene contains a lot of lighter than average or darker than average tones it won't work nearly as well.

Let's take a look at a scene where the camera's assumption about the scene being of "average tone" is wrong:



The background of this photo is white. Not only that, but the background makes up more than 50% of the photo, so that's a lot of white! If the camera assumes that the scene as a whole should be of an "average tone" what you're likely to end up with if you take this shot with the default settings is something like this:

















Hopefully that makes sense. ...the camera doesn't know the background is white. All it knows is that the scene should be of an "average tone". So, to compensate for all that bright white, it tones the whole photo down and makes the white look gray.

That's why, when your scene is not of "average tone", you need to choose one of the other metering modes that your camera offers. Your choices of metering modes usually include "spot" and "center weighted".

"Spot Metering":
"Spot metering" is usually my preference since it gives you the most control. The idea is rather simple, you just point your center autofocus point at something in your scene of "average tone" and your camera will only use that exact point to determine your exposure.

So, if in the apple photo above you pointed your center AF point at the apple, the scene would likely come out correctly with the white background appearing white instead of gray as it would if you used "evaluative" or "matrix" metering. If you pointed your center AF point at the white background, you could expect the photo to turn out the same or darker than what you'd get using "evaluative" or "matrix" metering.

Let's try one more. Here's a new scene:


What would you expect to get if you use "evaluative" or "matrix" metering for this scene?
What would you meter off of if using "spot" metering when taking this photo?
...the answers are at the bottom of this article.

"Center-weighted" metering:
"Center-weighted" metering uses a fairly large circle in the middle of your scene to determine exposure while ignoring the tones at the edges of the photo. Since it's not clear what is and is not included in this circle where your exposure is evaluated, this mode doesn't give you the same level of control as "spot" metering does. So, I tend to use "evaluative" when I want to let the camera do the work, or "spot" when I feel I need to take control over the exposure for the shot. "Center-weighted" is kindof an in-between mode that I just don't find all that useful.

Answers:
So, if you took the photo of the purple flower on the black background in "evaluative" or "matrix" metering mode, you'd expect the camera to try to make all that black more of an "average tone". That means, it'd brighten it up to make it gray instead of black; so, you'd get a washed out version of the photo. If, however, you used "spot" metering and metered off of the open purple flower you'd likely get the black background to come out black as it did in the photo above.

Questions? Leave a comment or ask about it on my "photography_beginners" mailing list!

When Auto Mode Fails

I've posted about this experiment you can do before, but this time I'm posting about it in video form! :-)

This lesson will teach you why pictures of snow scenes tend to come out with the snow looking gray as well as why other pictures that are taken of overly light or dark scenes often don't come out the way we'd expect. I also go over how to compensate for it.

Calculating for long exposures (or how Shutter Speed and Aperture relate Part II)

This article is kindof an extension of this one here. You may want to read the previous one before continuing.

When you want to take photos at night that require shutter speeds of over 30 seconds, you're left to calculate the settings on your own. If you grab your camera and put it on Manual Mode, set the shutter speed to 30sec, and then go one more setting down, you'll see "Bulb" or "B". When you put the camera on "Bulb", you'll should notice that it won't calculate aperture or give you a meter to read to see what your exposure will be. This is because with "bulb", the shutter speed depends on you to open and close the shutter manually. You do this with a bulb cable that will allow you to push a button down to open the shutter, and then lock it down to keep the shutter open until you release the button to close the shutter.

So, how do you know how long to keep the shutter open? Well, this is where the ability to add and subtract stops of light comes in. If you understood the previous article, then it should be easy:
* set your camera to aperture priority and dial in the aperture priority mode
* dial in the aperture you want to use
* set the ISO to 800 or 1600 -whatever will give you a shutter speed of 30sec or close to it
* take a test shot -does it look close to what you were hoping for? If not, use exposure compensation to tweak it now instead of tweaking it when you're waiting 5min between shots (I never remember to do this, but often kick myself for not doing it after the first shot :-P)
* when you get a good shot, write down or remember the settings you now have for shutter speed, aperture, and ISO
* switch to manual mode and choose "bulb" for your shutter speed
* do the math to dial the ISO down to reduce noise while using longer shutter speeds to keep the exposure the same

The following will all give you the same exposure:
30sec f/16 ISO 1600
1min f/16 ISO 800 <-- subtract 1stop of light w/ ISO, add 1stop w/ shutter speed 2min f/16 ISO 400 <-- ditto, on down the list 4min f/16 ISO 200 8min f/16 ISO 100 If it's really dark or you're trying for longer shutter speeds, to get star trails for example, then you may need to use a smaller aperture for your first 30sec exposure as well, then calculate a smaller aperture for more depth of field as well as for reducing ISO. It makes it a bit more complicated, but not by much: And here's an example for even darker photos (like star trails): 30sec f/4 ISO 1600 <-- subtract 2 stops of light w/ aperture, add 2 stops w/ shutter speed 2min f/16 ISO 1600 <-- ditto 4min f/16 ISO 800 <-- subtract 1stop of light w/ ISO, add 1stop w/ shutter speed 8min f/16 ISO 400 16min f/16 ISO 200 32min f/16 ISO 100 I literally write this out if I can't do it in my head while doing long exposure shots. There may be an easier way (tables?), but a quick google search of this question on Flickr and several forums reveals that most people just calculate it out this way. After you get the idea of adding a stop and subtracting a stop, than it's just a matter of remembering how the settings effect light. If you aren't 100% sure about it, it's easy enough to write/print out the following on a small slip of paper, "DIY laminate" it with packing tape, and keep it in your camera bag: * Shutter speed: more time = more light * Aperture: lower number = more light * ISO: higher number = more light

* For shutter speed: 1 stop = half or double the number

* For aperture: 2 stops = half or double the number

* For ISO: 1 stop = half or double the number

Using HDR to overcome harsh mid-day sun and shadows

I was on a tour in St Thomas that let us off at Megan's Bay for 2 hours before continuing on to other destinations when I came across a boat chained to a tree near the beach that I really wanted to capture on film. The problem was that the bright caribbean sun was in full force and it was the middle of the afternoon. As a result, there were harsh shadows from the tree all over the boat.

I knew from experience that while the scene was pleasing to my eye it wouldn't be captured in a photo as nicely. This is because the "dynamic range" (or the range of light vs dark) that the eye can see is a lot bigger than the range that the camera can record. The result would be either the areas in full sun being exposed properly or the areas in shadow being exposed properly, but having both areas look right would be impossible. So, I made sure my camera was set to take photos in RAW and I took a kindof middle-of-the-road photo making sure the histogram showed no data loss on the light or dark ends and here's the result without any editing:



Then, when I got home, I opened the photo in my RAW editor of choice (Canon's Digital Photo Pro or "DPP") and I used the brightness tool to make a copy of the photo that was 2 stops brighter than the original, then another that was 1 stop brighter, then another that was exposed normally, then 1 stop darker, and the final one at 2 stops darker.

The above is the "fake" part of "fake HDR" photos. For real HDR photos, you'd take separate shots at each exposure (+2, +1, 0, -1, and -2 or whatever will cover the dynamic range of the scene you are shooting). But, by shooting in RAW, you can record almost all of that data in one shot so you don't have to worry about the camera moving in-between the shots. I take the time to do 3 to 5 shots when the photo is important and I have a tripod handy, but I find that the "fake HDR" technique works just fine most times. (But I'm a relative HDR newbie, so take my advice there for what it's worth.)

What next? Well, you get some HDR software. I use FDRtools Basic (the free version of FDRtools). There are a lot of different programs available for HDR, so you can google for them to find one that you like. But basically, you feed it your images and the software will spit out a more even-toned version of the photo. You can tweak it if it doesn't automatically come up with what you were looking for. Some prefer a more cartoon-like appearance, others like it to be more subtle, the effect is up to you. But here's my result:



Better, don't you think? This looks a bit more like what we see with our eyes in mid-day conditions. So, while you should listen to the rule of thumb that says you'll get bad results in mid-day sun, now you know there's a work-around for it! Ahh... technology. :-)

How aperture relates to shutter speed and vice versa

Learning how aperture and shutter speed (and ISO) relate to one another is an important thing to know when you're learning to use manual mode as well as the priority modes. But, this too is easy!

If you find a combination of settings that gives you the magic "0" reading on your meter (which means the photo should be exposed properly), and then you want to change the aperture value to get more depth of field, it's fine -all you have to do is some elementary math:

You may have heard of a "stop" of light? That's what those numbers on your exposure meter are -"stops" of light.

(Your exposure meter looks like this: [-2...-1...0..+1..+2] although Nikon flips the numbers around.)

The handy thing about measuring light in "stops" is the fact that when you half or double the number you use for ISO, aperture, or shutter speed -that's a "stop". So, in this example, if you remove a "stop" of light by using f/8 instead of f/4 your photo will come out too dark (at -1 on your exposure meter). But, by doubling the shutter speed to ADD a stop, you'll be back at "0" (correct exposure)! But if we want f/16, then you're doubling the number twice, so we have to half the shutter speed twice, which gives us 1/250 at f/16.

All you have to remember is how the settings effect the light that hits your film or sensor:
* Shutter speed: you gain a stop of light by halving the shutter speed.
* Aperture: you gain TWO stops of light by halving the number.
* ISO: you gain a stop of light by doubling your ISO.

So, as an example assuming your ISO is set to 100 and doesn't change, 1/1000th at f/4 would be the same as all of the following:
* 1/500 at f/5.6
* 1/250 at f/8
* 1/125 at f/11
* 1/60 at f/16
* 1/30 at f/22
...if you wanted a shutter speed of 1/15 you can't double your aperture to 1/32 -that setting isn't available on most lenses. So, you'd have to get that extra stop of light by doubling your ISO instead.

So, assuming your aperture was set to f/4 and doesn't change, 1/1000 at ISO 800 would be the same as all of the following:
* 1/500 at ISO 400
* 1/250 at ISO 200
* 1/125 at ISO 100

If you're not one for math you could even just count the clicks up from f/4 to f/16, then change the shutter speed down by the same number of clicks to get back to correct exposure. ...the math really isn't hard though.

This may be hard to read and understand, but it's really easy once you do it a few times. A great way to see this for yourself is with this camera simulator:
http://www.photonhead.com/simcam/shutteraperture.php


One reason that you may want to know how to do this is night shots. For exposures longer than 30 seconds, you need to calculate the settings yourself. More info on this can be read in Part II of this article here.

Exposure Experiment

I have a couple of ways of explaining how a camera determines exposure and why it sometimes gets it wrong, but despite my best efforts it seems to be a concept that continues to elude many people. Well, I've come up with a new way. A way that requires few words and should demonstrate the concept in a matter of minutes. Curious? Do the following:

• Grab your camera
• Put it on "Auto"
  
• Take a picture of something black that will fill the frame. It must be 100% black. Perhaps you could do a close-up of a blank black T-shirt so that the material fills the entire frame.
• Take a picture of something completely white that will fill the frame completely. A close-up of a white sheet of paper or a white wall should do.
  
• Compare the two photos

Questions? Comments? Leave them here or on my "Photography_Beginners" yahoogroup.

Getting sharp photos in low light

(Click on the photo for a larger version, the EXIF data, etc)

On Saturday I met Mike (ndisgr8) from my yahoogroup at Brookfield Zoo and we spent the whole day taking pictures. It was overcast in the morning, which made many of the indoor exhibits, which are largely lit up via skylights, very dark. As a result, it was extremely difficult to get high enough shutter speeds to get a decent photo in there. I figured this was a great example of low-light photography which everyone seems to run into as a problem from time to time, so here's a write-up about how I dealt with the situation and managed at least a couple decent pics from the ape house...

Equipment:
I was using my Sigma 50-500mm f/4-6.3 lens because this zoo gives the apes a lot of space to roam around and play, so I needed all the "zoom" I could get. For those who aren't familiar with the "f numbers" on lenses, it's included in the description of the lens for just this purpose (low light photography). The lower the "f numbers", the better the lens performs in low light. When you have a range of f-numbers like for this lens, it means that at the wide end (50mm) , 4 is as low of a number as you'll be able to choose for your aperture. At the long end (500mm), it's 6.3.

The reason this matters is as follows: The lower the aperture number, the faster your shutter speed can be. This is because as the aperture numbers get lower, you're letting more light into the camera, with more light via aperture, you can get faster shutter speeds (which allow less light to get in because the shutter doesn't stay open very long). -It's all a matter of balance.

Step 1: Aperture
This lens (the "Bigma") is not very "fast" (meaning it has relatively high f-numbers), so it really limits me when there's not much light. Because of this, I immediately put my camera on aperture priority mode and set it for it's lowest aperture number so I could get the most light possible via aperture (which would, therefore, allow the fastest shutter speeds possible).

Step 2: ISO
Before even bothering to begin looking for photo opportunities, I also set my ISO to 800. The higher your ISO number, the faster your camera will record the light when you take a picture. So, in low light you want to choose a high numbered ISO.

The cost for using high ISO numbers, however, is noise. Most noise can be removed in software later, but there's always an effect on picture quality. You should, therefore, always shoot in the lowest possible ISO setting for the lighting conditions you are in. In other words, remember to set it back down to 100 when you're shooting in daylight again.

Each camera is different as far as how much noise it produces at different ISO's, so it's a good idea to experiment and know how your camera behaves and how well you can remove the noise it produces at each different setting. This way, you'll know not to go above (in my case ISO 800) or you're risking not being able to remove the noise from the photo effectively. -I did end up moving to ISO 1600 later on in the ape house as a last resort because I wasn't getting any clear shots at ISO 800.

Step 3: Check your shutter speeds
Next, I lined up a shot and checked my shutter speed. With most SLR's you can see the shutter speed in your viewfinder. In this case, I was seeing shutter speeds ranging from 1/10 to 1/60 most of the time.

Remember, the rule of thumb is that you need a tripod if your shutter speeds are faster then the reciprocal of your focal length. That's just a fancy way of saying that if you're shooting with a 500mm lens like I was, your shutter speeds should be faster than 1/500th of a second. If you're shooting at 300mm, they should be faster than 1/300th of a second, etc. (Although 1/60th of a second is as slow as you should go with any lens because it's hard to hold the camera steady enough when your shutter speeds are slower than that regardless of how wide the lens is.)

So, I needed shutter speeds that were up to 50 times what I was getting!

Step 4: Put your camera on a tripod
I had a monopod with me just because my lens is so heavy, but I didn't have a tripod. So, I leaned the monopod against the railing and steadied it further by bracing it against side-to-side movement with my foot. A tripod would have made it more steady.

Of course, the monkeys and apes were rarely perfectly still, so even with a tripod, you'd still get blur unless they happened to stay still during the shot.

Step 5: Use burst mode
If you've done all you can with settings and steadying the camera, but your shots are still coming out blurry, your best bet is to take as many shots as possible. Many people aren't aware of it, but they jerk the camera a bit when pushing the shutter button to take a photo. That may be contributing to the blur, so if you put your camera in burst mode you can hold the shutter button down and it'll take several shots one after the other. Even if you're sure you don't jerk the camera, just by shear volume, this will increase your chances at a clear shot.

Step 6: Get creative!
I was doing all of that as well as trying to concentrate only on the apes that were in the best light and I was still having trouble getting clear shots. So, for a few shots I decided to try something different. I was shooting in RAW, so I knew that I'd have a good chance of getting most of the data out of a photo even if it was severely under-exposed (dark), so I intentionally under-exposed several photos as a last resort.

Your camera should have an exposure meter that looks like this: [-2...-1...0..+1..+2] and there's a small indicator that shows you your current exposure setting. "Zero" is normal exposure, but if you use exposure compensation to move the indicator towards the positive numbers, you're telling the camera to over-expose the photo by that amount. When you move the indicator towards the negative numbers, you're telling it to make the photo darker (under-exposed).

Darker photos are a result of letting less light into the camera, so when you move the exposure down into the negative numbers you should get higher shutter speeds. When you're shooting in RAW you're often able to lighten up the photo by up to 2 stops (which correlate with the numbers on that exposure graph on your camera).

So, I moved the exposure meter down to -2 and took a shot. I reviewed the photo on my LCD and turned on the option to view the image's histogram. I made sure the data didn't run off either side of the graph (because that indicates that you're missing data, which you can't get back even in RAW). The photo was very dark, but the histogram looked ok, so I tried a few shots like that and hoped I'd be able to "save them in software" later.

Summary:
The photo above is one of the ones I took on ISO 1600 and under-exposed by 2 stops, then "saved" in the RAW software that came with my camera (Digital Professional Pro). The "right" solution to this kind of a problem is a "faster" lens (meaning a lens with lower f-numbers), but everyone eventually finds themselves in a situation where they didn't expect to have a low-light issue and they need to do what they can with what they have. Hopefully, this write up has given you some ideas for the next time you're shooting in low-light.


Extended reading / other resources:

• How to read histograms here: http://blog.muddyboots.org/2009/02/histogram-basics.html

Playing with histograms

First, you have to understand histograms. If you don't, read about them here:
http://photography.muddyboots.org/histogram

Then, check this out 'cause it's quite cool!
http://www.ironicsans.com/2007/09/idea_the_histogram_as_the_imag.html

Photos coming out too light or too dark?

The "problem" is probably your camera's exposure meter.

Cameras are simple devices and one of the assumptions they make is that the overall tone (how light or dark the overall photo is) will average out to a set medium tone (~18% gray, which is about the same tone as the skin on the palm of your hand). If large portions of the photo will be darker than the assumed tone, the camera will think the reason for that darkness is lack of light and it'll brighten it up to make up for it. And the opposite is also true -with extremely light-colored scenes, the camera will think that the lightness is due to too much light, and it'll make them darker so they come out gray.

So, if you have a dark scene that you're shooting and you want to tell your camera that the scene should be darker than that "average tone", you have a few choices: #1. If you want accuracy, you can buy a "gray card" to calibrate your camera to the lighting conditions, set the exposure, and take the photo. #2. To get pretty close, you can meter off your hand. Or, #3, you can use trial and error like I do most of the time -just use exposure compensation in whatever mode you're shooting in:

Exposure compensation uses the exposure graph you see and use in manual mode or the "priority modes", it looks like:

[-2...-1...0..+1..+2]

..(Note that on Nikon's it's reversed and the positive numbers are on the left). There's usually a small marker under the numbers that indicates where your exposure is on the graph using whatever settings the camera is on. The "0" on the graph indicates what the camera thinks is proper exposure (assuming that "average tone"). Setting the exposure towards positive numbers means you're telling the camera to add light or brighten the photo as compared to what the camera would usually choose. And negative numbers, then, darken the photo as compared to what the camera would choose to be correct.

So, if the camera is making your snow scene turn out gray (it's coming out too dark), you need to brighten the photo, or expose more towards positive numbers. Try exposing at +1, then adjust up and down from there until you get the result you desire. On the other hand, if you're taking a photo of your black cat lying on a dark blanket, it'll likely come out too light, so you'll have to expose towards negative numbers to darken the photo. Try -1, then adjust up or down from there.

Experiment:
If you want to see just how wrong your camera's meter can be, find an all white subject (a wall or your ceiling should work), and an all black subject. Take a photo of each. Lighting shouldn't matter, but you can try adjusting the lighting to prove that it has no effect -just make sure the lighting is consistent over the entire area that you'll be taking a photo of. You can add subjects to your photo as long as they too are 100% white or black (you'd want to take a photo of a white subject against a white background, then a black subject against a black background). If you want to take it even further, you can switch subjects and backgrounds and take 2 more photos (white subject on black background and vice versa) -those should come out mostly correct since the two tones (one dark, one light) will average each other out. My photos are here if you wanna cheat ;-)

Your 100% white and 100% black photos should all come out almost the same shade of gray no matter if your subject was all white or all black. -That's what your exposure meter is designed to do! Most of the time it works just fine, but when you have a scene that's made up of extremely light or dark tones, remember this and use exposure compensation to make the photo come out as you see it instead of all gray.

ISO -What it is and when to change it.

If you owned a film camera, you may remember going into the camera shop and having a bunch of different film speeds to choose from. Most of the time people stuck with 400, or turned the package over to find out which one was right for the conditions they'd be shooting in. There was 100 speed film for "sunny days", 200 for outdoors/cloudy, 400 indoor with flash, and 800 was for "low light". Digital cameras retained the idea of film speed in a setting called "ISO".

Either way, "film speed" or "ISO" is a measurement of how fast the film (or your digital camera's sensor) will record the light that makes up your photo. The faster it records, the higher the number, and the better it'll perform in low-light situations. -Have you ever tried taking photos inside and they came out blurry? If you would have used a faster speed film or a higher ISO, you'd get less of that blur because the camera would have been able to record the image faster.

Of course, you don't get something for nothing. There's a tradeoff for choosing a higher ISO, and that's image quality. With film, you get graininess. With digital, you get noise (those grainy, multi-colored specks that you sometimes see in digital photos). There are programs out there, like Noise Ninja or Neat Image that can help reduce the noise in your photos, but generally it's best to keep the ISO as low as you can for the conditions you are in.

(Below is an example of a noisy image:)


















So, if you see that your low-light photos are coming out blurry on your camera, try raising the ISO number to the lowest number that gets you clear, unblurred photos. (Then remember to put it back to 100 when you're done so you don't end up taking photos in daylight at ISO 800 and get unnecessarily noisy photos as a result).

This is one of the 3 things you can adjust when using your camera in Manual Mode. So, if you are wanting to learn Manual Mode, this is an important concept to understand. -With ISO, a bigger number means more light can be recorded in a given amount of time.


**NOTE** Film speed and ISO are not exactly the same, but they are close enough that for our purposes and, especially in this intro, you can treat them as if they are 1 to 1.


If you don't understand something or have trouble with any of my tips, feel free to contact me via a comment on this (or any) article, or see my website for my email address and I'll be happy to help you out!

An introduction to histograms...

Does your camera have an option to show a photo's histogram? (If you aren't sure, check your manual.) If so, and you don't know what it is, read on! You're missing out on a very powerful tool!

It's nearly impossible to tell if a photo you've just taken is too light or too dark (or "exposed properly") on your camera's LCD screen. In bright sunlight you have to shade the screen with your hand, then squint and zoom and in the end you really have no idea until you view it full size on a screen. Even under the best lighting conditions it's difficult to evaluate exposure on the LCD screen because the brightness on the screen itself can be adjusted -so is it right? or just right on your tiny LCD screen? This is where your histogram comes in handy!

Before we get to what the histogram is, let me break down the term "tone" for you (sometimes people get confused by what a color's "tone" really is). By tone, I mean how dark or light a color is. Any color. In other words, if you converted the photo to black and white, it's all the shades of gray between black and white.

So, your histogram will show all the tones in your photo in a graph that goes from black (usually on the left) to white (on the right). You can think about it like this: it converts your photo to black and white, then takes all the pixels and lines them up on the graph -all the black ones are on the far right, then 99% black, 98% black, etc all the way down the line to pure white on the right. ...it's an interesting but abstract thing to do, right?

So, here's why it's useful... If your graph shows a lot of data on the far left (black) side of the graph, you have no detail there. That means, no matter how much you lighten it in post-processing you'll never be able to get anything out of those areas -they are pure black.

Of course, a lot of black isn't bad for all photos. -If we're talking about a photo of a person with a pure black background a lot of pure black would be expected. But, if it's a photo of a bird up in a tree, it's probably under-exposed.

Likewise, if the histogram shows a lot of data on the far right side (towards white), then you have very little detail in the highlights of the photo. But, again, if you took a photo with a pure white background that would be expected. If you wanted detail in the white areas of the photo, however, you'd want to re-take the photo so the data doesn't run off the right side of the graph. (It should peak, then go back down before the graph ends on the right-side.)

It's difficult to understand the idea of using these graphs unless you see them, so here are a few examples of some photos and their histograms. The first 3 are kindof extreme examples, the 4th is a more normal photo. Note that on that one the data runs off the right-side of the graph (I overexposed it a bit!).

(Click on the photo for a larger version and an explanation of what the histogram shows.)










If you don't understand something or have trouble with any of my tips, feel free to contact me via a comment on this (or any) article, or see my website for my email address and I'll be happy to help you out!