I have a 3.2 megapixel camera with a 3x optical zoom. Let’s say I want to get a nice picture of a person, but I’m far away. I zoom all the way in and then take the picture. When looking at the picture on my computer, I crop it so it’s only the person. However, it’s a little pixelated and not all that detailed.
Probably the best approach is to get a camera with more optical zoom that lets me get in closer. However, couldn’t I also just get the same camera with 5.0 megapixels and take the same picture? When I perform the crop, the person will be more detailed because there are more pixels constituting it.
Does this make sense? I know that optical is certainly better, but leaving that aside, is my logic correct? Does this work in real practice?
Your logic is correct in theory…however, the actual increase in resolution from 3 to 5 megapixels is pretty small…you will have more detail of the person, but not so much that you go from a “hey that’s a person” to “I can see his nose hair!”
Not to mention that the very small lenses and very small sensors, plus high sensor noise from the compact digitals does somewhat limit the detail you get from a rise in megapixel count.
You will find that in practice, a 6MP image from a digital SLR camera (which has a large sensor), fitted with a quality lens will have FAR more detail, especially when enlarged to sizes of 13x19" or larger, than a 10MP small sensor compact digital camera.
It works in real practice. While a hypothetical 2-Gigapixel camera probably would not let you take snapshots of the moon’s surface as cleanly as you could photograph it with your current camera attached to a decent telescope, a good 7-megapixel camera will take pix of astonishingly good detail and resolution.
Good info from other posters. In the past, I pretty much ignored the digital zoom figures, and looked for an optical zoom of, at the very least, 4X. There are a few smaller point-and-shoot cameras out there that have greater optical zooms, but sometimes scrimp on other features. Have seen zooms up to 12X in these cameras.
Otherwise you will have to look at the SLR jobs, which are more expensive, bigger and heavier. And, of course, a lot better!
Note that a 2X increase in X and Y resolution results in a 4X (square law) increase in the number of pixels. So figure your “real” resolution increases only as the square root of the pixel count. Camera manufacturers like to use megapixles as a figure of merit because it is a bigger number. 4 Mpix “sounds” twice as good as 2 Mpix, but in reality is only 1.4 times improvement in resolution.
I have a sortof related megapixel question. I have an HP 2.1 megapixel camera. Nothing fancy. I’m not really into fancy anyway. But would I gain anything by getting a camera with higher megapixels? I probably wouldn’t enlarge anything to bigger than 8 X 10. With the camera I have now, when enlarging to 8 X 10, the pictures seem to be a bit grainy, although not terribly so. So should I upgrade or just keep the camera I have? Thanks.
There is an unfortunate flaw in that logic that isn’t very obvious. Given the same sensor size more pixels may not be any better proportional to the greater pixel count and very often worse. Smaller photosites, the individual sensitive areas, each collect a smaller share of photons whichh makes the ratio of signal to inherent electrical noise worse. Also the distribution of photons becomes more irregular further increasing noise and since each photosite has less information there is less dynamic range, the ability to record a wide range of light to dark.
Manufacturers build more sophisticated image processors to reduce noise but this typically comes at the expense of detail. It’s a sad state of affairs but the general public only knows that more pixels must be better.
You can take steps to make the image as good as it can be. If your camera has an ISO setting - the sensitivity to light - use the smallest value. My modest little Canon A75 makes nice images that print at 8x10 when shooting at ISO 50 but it quickly turnes to shite as you raise the sensitivity. If there is variable JPG quality/compression set it to finest quality and highest resolution.
