Article: How Many Megapixels Do You Really Need in a Digital

Joined: 16 Apr 2005 Posts: 23 Location: Singapore

Here is an article I published on my website about the number of megapixels needed in a digital camera. I hope it'll be useful to some of you in this forum.

How Many Megapixels Do You Really Need in a Digital Camera?
by Gary Hendricks

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 4x6 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 4x6, 5x7 and even 6x9 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.

Posted: Sat Jun 04, 2005 11:36 pm

Excellent points however there are other matters to look at.

One common mistake is to assume that Megapixel (MP) count alone is a measure of quality. Image quality is a combination of factors. Color accuracy, color saturation, smoothness of tones, control of noise, etc. etc. all play a part. When looking at that, a 6MP Digital SLR can easily (yes easily) produce better images than an 8MP Point and Shoot camera. This is becuase of the physical size of the sensors and, by definition the size of the individual pixels. There are other factors as well, of course, like the lenses and camera software and options.

In short, don't think that image quality, overall, is only a factor of MP count. Many other factors come into play. So do your homework including touching and feeling the camera in your hands. The MP count should be in the latter part of the descision.

Premium Member Joined: 29 Oct 2004 Posts: 5758

I agree with Luis' points.

Firstly, you're not going to find a dSLR of recent vintage with less than 6 megapixels. Even my 300D digital rebel has been supplanted by the 350D (i.e. rebel XT). So Canon's baseline dSLR already has 8 megapixels. Why does a line have to be drawn here between an amateur's and a professional's needs? The number of megapixels in the camera you buy may be completely incidental to your choice of camera.

Additionally, it is a big mistake to categorize megapixel resolutions as if there is a linear, stepwise relationship between them. Megapixels are a square -- they are the pixel length multiplied by the pixel height. So a 1000 x 1000 pixel image has 1 megapixel, but increasing the pixels by twofold on each side -- to 2000 x 2000 -- gives you a fourfold increase in the total number of pixels to 4 megapixels. It's an exponential relationship.

The importance of that point is that there is a MUCH bigger difference between a 4 and a 6 megapixel sensor than between a 6 and 8 megapixel sensor. If we just use square roots to figure out the size of the sides, this is what we get (assuming for the sake of simplicity a square image sensor):

2 megapixels: 1414 pixels per side
4 megapixels: 2000 pixels per side (41% increase)
6 megapixels: 2449 pixels per side (22% increase)
8 megapixels: 2828 pixels per side (15% increase)

This is a logarithmic decline in the increased picture size that you get from increased pixel resolution. So to match the difference between 2 and 4 megapixels in terms of your final pixel size (a 41% increase in the size of each side of your print), you would need to go from 6 to an 11.9 megapixel camera! So the difference between 6 and 8 is essentially trivial. The difference between 2 and 4 is enormous. It's probably after 6 megapixels that the returns start really diminishing. So I'd submit that for the amateur photographer who wants to make mostly 4x6 prints with the occasional 8x10 or so, 6 to 8 megapixels is perfect.