Is it true that when you zoom in with a digital camera you lose quality, but use optical zoom and you won't?

Question

I have heard that if a camera has optical zoom and you zoom in with the optical zoom, you will NOT lose quality. True?

Answer 1

All digital zoom does is basically crop the image you take, this means you get a greatly reduced megapixel count, which equals a loss in quality, instead of using digital zoom, it's better to take the image full size and simply crop the image yourself on a computer when you get home, if you want to do so.

Optical zoom uses the lenses in the camera to increase the focal length, basically this does what it says on the tin, it zooms in, just like binoculars would do (random example), and the resultant picture has the same megapixel count as it would if you had not zoomed in, therefore there is no loss in quality.

Do note though, that when you optically zoom in, camera shake will have a greater effect on the image because you're focusing on a smaller area, and could blur the picture more noticeably (The same with digital zoom, but because of the drop in quality it would be less obvious, though to the same extent). That's why you should go with a camera that has optical image stabilisation (Usually referred to as OIS), it will greatly reduce image blur.

EDIT to Shorty below: If you get a good quality camera (High end compact, bridge camera, or DSLR) then the barrel distortion will be very minimal, if any at all.

Answer 2

I think in your question, you meant "digital zoom." What it does is it's enlarging the image in the middle of the camera sensor, which means that less megapixels are used because everything else is cropped out. It does lead to image degration- it's useful for getting just a wee bit closer to the subject, but I wouldn't overuse it.

Optical Zoom actually moves the lenses to create a longer focal length to "zoom" into the subject. This can also lead to bad image quality however at the wide and telephoto end. Why? High zoom lenses have to compensate for a huge range of aberrations and distortion due to its zoom range when compared to a 3x zoom or a "prime lens." Prime lenses are of fixed focal length, which means it can't zoom, but at the same time, offers superior compensation for all types of distortion. To most people however, the distortion is minimal and usually goes unnoticed unless you print at poster sizes.