[muglo] Re: Camera Zoom

I hope this hasn't been pointed out later on in this thread.

There *are* SOME situations on SOME cameras where digital zoom actually 
_does_ capture real info to a pic. If you are using a pic resolution that's 
lower than the max resolution of your camera's CCD (the "film") some cameras 
will actually allow you to zoom in (crop) on the middle of the image above 
and beyond the magnification allowed by the actual lens.

So, let's say you have a 3 mega pixel, 10 x zoom camera. With a 3 MP camera, 
the CCD captures images at 2048x1536. You have set your camera to save 
1024x768 pictures. If this camera has said snazzy digital magnification 
feature, digital zoom will allow you to capture a _real_ 20x magnified 
image. However, you could get the same effect by shooting at 2048x1536 and 
cropping the resultant image to 1024x768 in your editing software (e.g. 
iPhoto).

There's a second situation where SOME cameras can use "digital" zoom without 
doing any actual fake zooming (interpolation) and that's during filming. My 
Olypus C730 does this and it's kind of cool (a replacement for a dearly 
missed Canon A70... not as good as the A70 in nearly all respects 
(especially manual features and video <grumble>) except for its 10 x zoom). 
Olympus (and others) disables zooming of the lens whilst recording audio 
because zooming a lens in and out usually generates a lot of noise. 
Fortunately, you can still make significant use of digital zoom on the 
Olympus b/c the camera crops the image coming from the CCD. Normally video 
is downsampled (right term?) from 2048x1536 to 320x160 (IIRC) to make a 
320x160 movie. Instead of downsampling, the camera crops the center of the 
image (~6x zoom) in the "real" digital zoom way of zooming to fit the movie 
being made.

It's not a major feature, but it is nice when you've got it.

I should add that some manufacturers (Fuji IIRC) do have an additional 
"super sized" mode where they save pictures that are larger than you'd 
expect their CCDs to allow them to capture. Most of these are simply 
interpolated images (digital zoom) but some cameras do capture additional 
detail. e.g. Fuji advertises one of its cameras as 6 megapixels when in fact 
it's simply a 3 megapixel that can save 4096 x 3072 interpolated pics (kind 
of pointless except if you want to fill up your camera even faster).

In one case (can't remember brand) a 3 megapixel camera was taking pictures 
on which it was possible to resolve between finely spaced lines that normal 
3 MP cameras end up blurring into one or a few. The layout of the sensors on 
the CCD allowed for add'l info to be captured.

PS Hope this makes sense...

Eric.

>Paul,
>
>Optical zoom is critical, and provides real magnification so you can frame
>your shot properly.  Digital zoom is next to useless, and pixillates very
>quickly.
>
>-Jim
>
>on 4/7/04 10:42 PM, Paul Thomas at paul_thomas@xxxxxxxxxxxxx wrote:
>
> > I am considering the purchase of a digital camera and wondering about
> > the importance of Zooming and notice that there is both Digital Zoom
> > and Optical Zoom - what is the difference and which is the more
> > important?  Maybe this is a dumb question - but I would like to know!!
> >
> > Paul

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