Photography. how significant is the loss of megapixels while zooming?

Question

is buying an 18x zoom camera useless when you only have 8-10 megapixels?

what is the estimated mp when you are zoomed all the way in at 18x?

Answer 1

Depends. There are two kinds of "zoom" mechanical and digital. mechanical zoom is like moving closer to the subject. It does not change the resolution. digital zoom is like enlarging the picture. Think of it this way. If you were viewing a 4X5 picture from across the room and wanted to see it better, you could either move closer (optical zoom) or enlarge the picture (digital zoom.) moving closer will not affect the resolution, but obviously enlarging it to poster size would. So it depends on the ratio of digital to mechanical zoom. If it is entirely optical zoom, you have effectively   the same resolution (megapixels) throughout the entire range. If it is entirely digital zoom, then it would be like enlarging that 4X5 to 72x90 (4X5 X18) or enlarging it to the size of a wall. So, you can ignore the optical factor as it does not change resolution, but the resolution will decrease by the square of the digital zoom. In other words if it has a 2x digital zoom, the effective megapixels  at zoom would be one fourth of the original.

Answer 2

if it's optical zoom, the sharpness is depends on how good your lens are, not the sensor (it's the same in all zoom range).

if you plug your camera (DSLR) into a telescope with 500x, your image quality wouldn't get degraded by that factor.

Answer 3

It means the picture will not be as clear, or sharp. I dont know the estimated mp at that range, but it will not be as clear of a picture definitely.

Answer 4

You need to check and see what part of that zoom is optical and which part is digital. Optical zoom means it's an actual feature of the lens and you will lose no resolution. Digital zoom, however, is a feature of the camera to make it seem like it has more zoom. This drastically reduces image quality.

18x optical zoom would be fantastic! However, I would seriously worry about distortion with that much zoom. Professionals use mostly prime lenses: they have no zoom, but no distortion and the most accurate colors and sharpness.

Also, don't say "only" 8-10 megapixels. For the average person, that's plenty. If you're making 4x6 prints at 300dpi (the standard for good-looking prints) you only need 3.6 megapixels. Yeah. Plus, if you went with a camera that had much more than that in the same price range, I'm betting that it would be very slow continuously.

Answer 5

zoom does not change the megapixels. it changes the focal length and aperture of the lens. your pic gets grainy because of the limitations of the mechanical parts of the camera not the digital parts.

Answer 6

The only time you should lose resolution during zooming is if your camera is using what they like to call "digital zoom" or what those of us who like the truth like to call "crop and resize".  When a camera uses "digital zoom" all it does is crop a box in the center and resizes it to the camera's resolution.

You can avoid this by only using optical zoom.