Digital cameras 101

[Andy]

Question about digital zoom. For example if you have a 5mp camera with a 5x digital zoom. Can you tell someone that when your shooting at 5mp that each X you  zoom in  basically takes away one megapixel? So when they are using a 5mp camera zoomed to 5x your end result is basically 1mp.

   Thanks...

   Andy.

[ShutterbugGail]

Hi Andy,

Welcome to the Digicamhelp Q&A Board.

I'm not quite sure I fully understand what you're asking, and I apologize. Let me try to give it a shot. I think you're talking about the way an image will look (ie. it may look like it was taken with a lower resolution digital camera), not the actual file size of an image taking with a digital zoom.

The actual length of the lens does not change as when using an optical zoom, which is a true zoom.  A digital zoom simply pre-crops and enlarges the central portion of an image and reduces its resolution giving an appearance of zooming in. This is similar to when an image is cropped using  photo editing software.

To put it another way, digital zooms decrease the number of pixels in an image by enlarging and showing less of them.  Digital zoom lenses produce images with reduced resolution and less visual quality than an optical zoom. If it can be avoided, it's better not to use a digital zoom.

I hope this helps answer your question.

[Andy]

Thanks for the welcome.

Hmm.. let me rephrase my question. Is there a formula you could use, when using a digital camera that has no optical zoom, where you can plug in the MP of the camera... then how much digital zoom you are using. Then get an estimate of the end  results 'resalution' in  MP.  So... for instance if you use a 5mp camera at 5x digital zoom... you could know what MP end result you will have to work with like for printing purposes.


      Thanks again,

      Andy.

[ShutterbugGail]

Hi Andy,

I'm personally unaware of any formula, though that doesn't mean it doesn't exist.  You can get a lot of information...after you take a photo..such as image size and resolution by using a software program that reads exif data from jpeg images. Take a look at the link below and let us know if this is what you are looking for.

Related reading:

What is EXIF?
http://www.digicamhelp.com/what-is-exif/