what does the numbers in the zoom of a digital camera means?

Question

can you explain somtimes it says 3xoptical zoom and then another 4x something else zoom and which is higher what about 7x

Answer 1

The number refers to the focal length at the long end of the zoom divided by the focal length at the short end of the zoom. A lens that zooms from an equivalent of 35 mm to 105 mm (very common) is said to be a 3X 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.

Answer 2

Optical zoom is determined by how much the camera can refocus. A 3x optical zoom means that the camera lens can adjust so that an object appears 3 times closer. The other kind of zoom in digital zoom, which is done by adjusting the picture and zooming in on it. It's the difference between being three times closer (optical zoom) and cropping an image (like with Photoshop) so that it LOOKS bigger(digital zoom). More optical zoom is better, because you get a clearer picture, but digital zoom can be good also. For the best detail look for a camera with high optical zoom.

Answer 3

Optical zoom is the ability of the camera to zoom in with the lens. Digital zoom is the ability of the camera to zoom in with it's computer chip. Optical zoom is far better than Digital zoom. 1X zoom means you can zoom the cameras lens 1 time. Anything multiplied by 1 equals the original number, so 1X means there isn't any zoom feature. What you see is what you get (it's a phone, so what do you expect).

Answer 4

Actually what you should keep in mind is the optical zoom, the higher optical the more practical it is. Since Optical Zoom is the one that really amplifies the image before it hits the sensor in the camera. This translates to that image amplification done through lenses (optical) would be amplified “fiscally” and less distortion would be present. Different from Digital Zoom, What this does is grab the image already received and mathematically amplifies it. It does amplify the image but to do this it applies and fills the (needed) pixels by sampling the one next to it. In short, picture it like a balloon, the image is originally printed on the empty balloon, now think what happens to the image when you inflate it.

Answer 5

I'm just chiming in to agree with the above. When you're shopping for cameras, only consider the optical zoom.

Digital zoom is a gimmick. You can do digital zoom on your computer. In fact, Dr. Sam's links demonstrate that you can do a BETTER job on your computer (and for that, he'd get my vote for Best Answer.)

Most people only need a camera with 3x optical zoom. That's enough for most situations, and those cameras are nice and compact.
On the other hand, if you like to zoom in a lot for sports, to shoots candids from 50 feet away, or for whatever reason, get a bulkier camera with 8x to 12x optical zoom.

Answer 6

On point-and-shoot cameras, zoom is described in relative terms from the widest angle to to closest zoom.
Let's say you have a camera that has 5X zoom, and you're taking a picture of 5 elephants standing side-by-side. You set the camera to the widest angle and step in close enough so that the 5 elephants fill the frame from one side to the other. If you now zoom in as much as the camera will go, you will only fit one elephant in the frame, but of course, that elephant will appear to be 5 times as big.

Answer 7

How many mm's it is at the widest compared to its telephoto end. So lets say the lens is 10-100mm, thats 10X Optical Zoom. 20-60mm, thats 3X optical zoom. Basically divide the largest number by the smallest number to get your optical zoom.

Answer 8

The numbers mean how far you zoomed in

Answer 9

it means how much closer the objects appear compared to 1 times zoom, which isnt any zoom at all.

Answer 10

That's wrong