What is a Histogram?
A histogram is a graph that displays how light is distributed in your picture. The left side of the graph represents the shadows, while the highlights are on the right.
That means that if the histogram has a high peak on the left, you can tell that a lot of pixels in the picture are dark, or in shadow. A peak on the right of the graph means that a lot of pixels are bright, or in highlights. Peaks in the middle of the graph represent pixels in the midtones of your exposure.
The Histogram of a Good Photo
Right, now let’s look at some examples of histograms. Refer to the picture below. On both the left side and the right side of the graph, you can see that there are no high peaks. This kind of histogram tells you that no part of the scene is over or underexposed. In other words, this shot should look good.
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The histogram of a good photo
The Histogram of an Underexposed Photo
Ok, now let’s look at the histogram of an underexposed photo. You can see a spike in the shadows that starts with a peak on the left of the graph. That means that the picture has lost data in the shadows. There’s also just a few pixels trailing off the right side of the graph, so a tiny bit of data might have been lost there as well.
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The histogram of a underexposed photo
The Histogram of an Overexposed Photo
You can probably guess how an overexposed photo looks. Here you can see a pronounced spike on the right side of the graph. Do note that the height of the peaks is somewhat low in this picture; that’s not an indication of under or overexposure. All you need to worry about is whether they breach the left or right edges of the histogram.
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The histogram of a overexposed photo
Conclusion
Well, I hope this article has given you some insight into how the histogram function of your camera works. When composing your photo, always try to avoid the histogram from spiking at either extreme end of the graph, where you’ll lose data and have under- or overexposed parts of your picture.
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If you’re out buying a digital camera, then one of the key deciding factors is the number of megapixels supported. The number of megapixels determines the how good your photos turn out. If you have too few megapixels, then your pictures will turn out crappy. Investing in a camera with too many megapixels, on the other hand, is an unnecessary waste of money. Personally, I feel that if you have unlimited funds, then, by all means go for that high end 8 megapixel camera. Otherwise, you certainly don’t want to waste money on extra megapixels you don’t need. A golden rule to bear mind: a camera with more megapixels isn’t always better. If your camera supports more megapixels, then each photo you take will be larger. This means that you’ll use up more space on your memory cards and computer’s hard drive.
If you have trouble deciding how many megapixels you need (I know I did when I bought my first digital camera), then the guide below will help. Essentially, you need to ascertain what size prints you want to get and what your budget is, before deciding on how many megapixels you want. So here we go:
1 megapixel or less: Cameras in this range (e.g. web cameras or cell phone cameras) have very low image resolution. Don’t expect to be able to print high-quality photos using these cameras. You can, however, email the photos or post them on your web site. The good thing about such cameras, of course, is their low price.
1 to 2 megapixels: My first digital camera was a Canon PowerShot S110 which only had a 2 megapixel sensor. Cameras in this range are pretty decent though - you can expect to print out great 4×6 prints at this resolution. Of course, if you want larger, blown-up protraits of your birthday party or holiday in Italy, then I would certainly recommend getting more megapixels. Cameras in this range should sell for around $100 currently.
3 to 4 megapixels: Most new point-and-shoot cameras these days tend to have at least 3 to 4 megapixel image resolution. Bring these images to the lab and they’ll be able to develop great looking 4×6, 5×7 and even 6×9 printouts. Expect to pay slightly more though - we’re looking at around $250 for a good model.
5 megapixels and up: The more advanced cameras tend to have image resolutions of 5 to 8 megapixels. Newer point-and-shoot cameras have 5 megapixels, while the newer digital SLRs come with 8 megapixels. The quality of images shot by these cameras is simply stunning. Of course, their price tags are equally stunning . In this megapixel category, expect to pay around $300 for a 5 megapixel camera and up to $1800 for an 8 megapixel SLR.
Conclusion
Well, now you know roughly the number of megapixels you should be shooting for depending on your intended usage and budget for the camera. My general advice is, if you’re just an amateur photographer, then don’t buy cameras above 5 megapixels. When you are really serious about digital photography and want to go professional, then consider buying a super high megapixel camera.
