I am considering buying a digital camera. One I am considering has 4.0 digital zoom and ,also, 6.0 optical zoom. How do the two features interact? 6.0x4.0= 24.0 zoom???? Optical zoom is a true zoom, bring you closer to your subject. The quality stays constant as you zoom in and out.
Digital zoom (shudder) enlarges the image. After a while, every pixel becomes large and obvious in your photos.
I'd recommend avoiding a purely digital zoom camera and looking at optical zoom first, second, and third. If your camera has both, try to stay in the optical zoom range.
The reality is, that you can digitally zoom any image in your computer after downloading.
I hope you find this helpful. You are excatly right in how the two features interact, but "don't count on it" as you won't like digital 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.
See: http://www.flickr.com/photos/samfeinstei... for one example. The difference is clear. Take note of the digital noise in the so-called digital zoomed image. This is typical. The optical zoomed image is not great, but this is taken with the same point and shoot camera as the other example.
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...
4xDigitalFull: http://www.flickr.com/photos/7189769@N04...
3xOpticalCrop: http://www.flickr.com/photos/7189769@N04...
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.
See also, about half-way down this page: http://photo.net/equipment/digital/basic... digital is the bad
optical is the good Optical zoom uses nothing but the elements in the lens. The image quality reaching the sensor stays the same through out the zoom cycle.
Digital zoom is done by the camera's electronics. Basically it takes the image the sensor receives and further zooms in on it. There is a noticeable loss of quality in a pictue taken with a digital zoom.
In short, optical zoom is done in the lens; digital zoom is done by the camera.
If you can't zoom in enough with your optical zoom lens, you will be better off manipulating the image on your computer. You will have much more control over the quality of the image because you computer has much more computing power than your camera. |
