What is Digital Zoom, Optical Zoom and MegaPixel in Digital Camera?

Question

What is Digital Zoom, Optical Zoom and MegaPixel in Digital Camera

Answer 1

Digital zoom is taking an existing image, and just magnifying or stretching it. Every time you magnify the image, it get degraded.

Optical zoom (prefered) is actually bringing the object closer to the viewer. It will always give you the best quality.

Using digital zoom is like stretching a sheet from a twin bed onto a larger bed. It might fit, but the material would be stretched until it weakened and might tear. Using optical zoom is like getting a larger sheet.

Megapixel is 1 million pixels of photo information. Digital camera resolution is measured in megapixels.
http://en.wikipedia.org/wiki/Megapixel#Megapixel

3 megapixel cameras are only good for 4x6 prints. 5-10 megapixel cameras will produce 5x7, 8x10, or 11x14 prints.

Answer 2

For megapixels well OK think of it this way, you could make a picture on a piece of paper simply by using colored pencils and drawing dots. The more dots you draw the more detailed your picture would be. No matter how many dots you drew, you could break the picture down into dots. All you need to know about each dot is what color it is and how hard you pressed the pencil.

Computers are as dumb as posts. They cannot draw a line or be in the least bit creative. However they are good at remembering a lot of stuff. So we teach them to remember information about each dot.

Being computer nerds we can't simply call them dots, that's not technical enough. So we call them "Picture Elements". Over time that has been abbreviated to simply "Pixel". Each pixel is one dot.

Now the more dots we have and the smaller the dots are in a given picture, the better the picture quality will appear to be. As cameras and computers got better, they remembered information about first thousands and then even millions of dots. But being nerds again we can't talk about millions, that's too simple, so we use the prefix "Mega" to mean millions. Therefore a one megapixel camera simply has an image made up of one million dots.

Entry level cameras these days tend to record 4 megapixels. Better cameras go up to 8 or even 10 megapixels. The Hasselblad H3D-39 can even record a massive 39 megapixels of data!

Now the more dots the better right? Well up to a point. After a while if we are going to print normal sized photos, we reach a point where the printer can't print that many dots and our eyes can't see that many dots, so going bigger is not necessarily better. Specifics vary but this generally happens around the 5 - 6 megapixel mark.

So why buy an 8 MP camera, it's a waste of time right? Not necessarily. For two main reasons:

1) More megapixels means bigger prints. Let's say you take that one killer photo that you love, wouldn't it be nice to blow it up to A3 or poster size?

2) Cropping. With an 8 MP camera, you can do a fairly savage crop on your image without losing too much quality.

As for zoom. Optical zoom is real, it's where the lens elements move to magnify the image. Digital zoom is where they effectively crop part of the image and expand it to full frame. This results in a poor quality image. This is also nothing you can't do on the computer later yourself, so stay away from digital zoom.

So I hope this clears up a little of the mystery for you! All the best with your photography!

Answer 3

Digital zoom is when the camera zooms in by cropping the image on your screen and making the area left larger so it looks like it zoomed in to a certain spot.

Optical zoom is when a camera uses lenses to close in on something. It basically the original way of zooming in with a camera.

A mega pixel is 1 million pixels. I dont know so much about this but I know that pictures from cameras with more megapixels can be stretched to big sizes without losing quality.

Hope this helps

Answer 4

Okay, you have excellent answers above and I'm just adding a little visual supprort to their answers. Choose someone else as the best answer (and please do choose), because I'm feeling lazy and just stringing together three of my standard answers to help you out a bit.

The capsule summary is to ignore digital zoom, choose optical zoom from 3-to-5 or 6X for best overall performance and getting a camera with 6-to-8 megapixels is going to be just fine.

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Digital Zoom vs. Optical Zoom

Optical zoom is good and digital zoom sucks. Optical zoom is "real" zoom done with the camera lens. Digital zoom is really just a way to enlarge pixels and degrade the image. Ignore it completely when you are comparing cameras.

Here are three sample pictures taken with my Canon Powershot SD900, which is a 10.0 megapixel camera. All three pictures are taken with the optical zoom maxed out at 3X or 23.1 mm, which is the equivalent of 111.6 mm after calculating for the lens crop factor. There is no image processing at all done with any of these pictures. All were taken using the self-timer to (hopefully) eliminate camera shake as the camera sat on the top of my car. (Okay, I'll use a tripod next time, but I think they are pretty sharp images.) Please click on "View All Sizes" and then view each image at the largest size available, which should be 3648 x 2736 pixels. The first picture (3xOpticalFull) is the full frame image at 3x optical zoom, or 111 mm. The second picture (4xDigitalFull) is the result of zooming out the additional 4x in digital zoom, for an equivalent of 444 mm. The third picture (3xOpticalCrop) is actually a cropped version of the original image, maintaining the full pixel dimension. In other words, I accomplished the "digital zoom" entirely in the computer and not in the camera. If you compare the full-sized images, I think it is immediately obvious that the third picture is far superior in any aspect that you care to examine. I think it is much sharper (Check the tower and the antenna up near the top of the frame.), has better color, and less digital noise and artifact (Check the plain sky and the shadows on the building.). These images are all tagged "digital zoom."

3xOpticalFull: http://www.flickr.com/photos/7189769@N04/459603923/
4xDigitalFull: http://www.flickr.com/photos/7189769@N04/459603931/
3xOpticalCrop: http://www.flickr.com/photos/7189769@N04/459603939/

In other words, please ignore any claims of superiority based on "digital zoom" when you choose your camera. It is only "in camera cropping" and it is not anywhere near as good as "in computer cropping." Any attempts at cropping a digitally-zoomed picture will be a waste of time.

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Pixels vs. Optical Zoom

Both factors are important, but neither one is the bottom line, decision maker. I'd rather have a digital SLR with 6 MP than a point and shoot with 10 MP if you are only considering image quality. When it came to my pocket-sized point and shoot camera, though, I chose pixels over optical zoom, because I can always crop in the computer. I included these examples in the section above.

Personally, I would think 6 or 7 MP is perfectly adequate for almost any shooting short of pro level photography. Put this behind a camera that zooms to an equivalent of 130-200 mm and there is little that you can't shoot other than some wildebeests half a mile away. You COULD go with a camera that boasts BOTH features, like the Canon S3-IS or S5-IS or the Sony DSC-H2 or DSC-H9. Then we'd have to have the whole discussion about image quality and sensor size, but that's a whole different matter...

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Pixels

If you always plan and compose your pictures perfectly, you don't need a whole lot of pixels. These days, I'd say that 5 MP or even 4 MP is fine for the average snapshooter and this can be obtained without unreasonable expense. If you want to allow for cropping, which means enlarging only a portion of your image, the more pixels the better.

Imagine taking a scenic view and then noticing that the middle 20% of the photo would make an even better picture. Suppose you take a picture of a whole group of people and Aunt Clara really, really looks great in the picture, but everyone else looks lousy. If you have the pixels to work with, you can still make a decent print of Aunt Clara that she would be happy to have. If you buy an 8-to-10 MP camera and don't want to TAKE large photos, you can always set the camera to a lower file size. You can never go the other direction, though. Unless the cost is a major issue, buy the camera with more pixels. You will never be sorry that you did, but you might one day be sorry that you didn't.

I have a few photos on Flickr to include in a discussion on how many pixels are enough. Go to my page at http://www.flickr.com/photos/samfeinstein/tags/pixels/ Some of the pictures are from a 4 MP or even 3 MP camera, showing you what you might expect without any cropping. I think they are quite acceptable. Some of the pictures are from a 10 MP camera (the swan and the pansies), showing the value of having those large images so that you can crop a smaller image out of the original picture and still end up with a satisfactory image. There is one VGA picture, just to show what you could expect from 640 x 480 pixels - not much.

Ken Rockwell has an interesting article on pixels and the pixel wars: http://www.kenrockwell.com/tech/mpmyth.htm

Having said all that, though, pixels are not the only measure of image quality. The sensor size is important as well as the image processing software included in the camera. (See http://www.flickr.com/photos/7189769@N04/476181751/
You need to read reviews if you want a critical understanding of image quality for particular cameras. Try http://www.dpreview.com/reviews/ for more information on the cameras you are considering. Pixels are not the decision maker, but they are the tie breaker, so go for the higher pixel count.

You can go there and click on "Buying Guide" and then "Features Search" to specify how many pixels you want to look at.

You can also go to http://www.steves-digicams.com/default.htm and click on "Our reviews," where you will find catagories of cameras arranged by pixel count.

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Answer 5

this will explain everything

my suggestion
go to yahoo shopping
digital cameras
digital camera GUIDE
be sure to check titles on the left side
the guide should answer your questions