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frogut Mar 21, 2003 6:27 AM

digital zoom
Does any digital SLR camera - with Focal Lenght Multiplier 1,5x or 1,6x - have an digital zoom possibility?
If so, one can use a wide angle zoom (16-35mm for example) and have a whole standard zoom range covered.
What do you think?


BillDrew Mar 21, 2003 7:41 AM

Remember TANSTAAFL*!

There are some subtle issues, but digital zoom is just cropping the center out of an image, then upsizing it, i.e., to get a 2x digital zoom, you throw away three quarters of your pixels. You don't have to do much of that to reduce your expensive digital SLR to the resolution of a BarbieCam.
*There Aint No Such Thing As A Free Lunch

Mike_PEAT Mar 21, 2003 8:18 AM

If you want to do a digital zoom with more control you can do it in a photoediting program after you download the picture to the least with that method you can have your original picture nice and sharp.

I turned off the digital zoom in my camera (but then again my camera has 10x optical and 2.7x digital).

sjms Mar 21, 2003 8:33 AM

mr dill drew said it with his usual style and grace.

my version is simple: digital zoom is the biggest waste of code/control in any digicam.

Dano Mar 21, 2003 11:16 AM

I just compared shots from the Nikon 5700 at maximum optical zoom (8x or 280mm equiv.) with the Canon G3 at maximum optical zoom (4x or 140mm equiv.). Same settings. I was testing the theory that I could crop the Canon shots to get the same effective zoom as with the higher priced Nikon.

In fact, when I cropped Canon shots to the same size print as the Nikon pics, the Canon shots came out sharper and brighter. I'm assuming this is because of the Canon's 2.0 lens vs. the Nikon's 2.8.

Any thoughts :?:

frogut Mar 21, 2003 11:20 AM

Thank you for your comments.
Generally I agree with all of you.

I look at it in a more specific way however.
Consider 6M pixel SLR camera with 1,6 multiplier and 16-35mm lens (26-56mm equivalent). To cover a standard zoom range we need to extend those 56mm to 80mm - by using a digital zoom for example. This reduces the number of effective pixels approximately twice at 80mm, to 3M pixels. OK, but having 3M pixels, sharp lens and good camera - we still can obtain a high quality image.
And this is the idea: to have only one standard zoom to the camera like Canon D60 or Nikon D100, with a little help of a digital zoom.

But so far nobody has told me whether such camera (SLR with digital zoom) exists.

normc Mar 21, 2003 12:05 PM

I respect the ideas on digital zooms but I have found it effective "at times". In photographing a small object like a bird with a spot focus, I can frame the picture and put that spot exactly where I want it. My C-2100 with the 1.7 telephoto and digital zoom will go out to over 47 times which is way more than can be used for effective picture taking but I have fun with it anyway.

sjms Mar 21, 2003 2:25 PM

yes, but will it give a sharp 8x10?

BillDrew Mar 21, 2003 4:34 PM


Originally Posted by frogut
... To cover a standard zoom range we need to extend those 56mm to 80mm - by using a digital zoom for example. This reduces the number of effective pixels approximately twice at 80mm, to 3M pixels.

Nope - getting a factor of two in zoom reduces the number of pixels by a factor of four. You are halving the field of view, or "doubling" the linear dimensions. Since the number of pixels used is the square of the linear dimensions, the number of pixels left after using a digital zoom is reduced by a factor of the square of the zoom.

If you used a digital zoom factor of three with a 6Mpixel camera, in effect you would be using 0.666Mpixel camera.

I very much doubt that a digital zoom will ever be found in any expensive digicam - the company that did it would be laughed out of business.

frogut Mar 21, 2003 5:18 PM

Therefore I am not talking seriously about 2x, 3x or 4x digital zoom, but only 1,43x (from 56mm to 80mm). Square of it is approx. two, so instead of 6M we get 3Mpixel image. Still enough.

Such "restricted" digital zoom could be very helpful in SLR digicams, but probably you are right and no one makes it.

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