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Old Jan 29, 2003, 8:39 PM   #1
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Default Digital Zoom - On or Off

I have an option on my digital camera (Canon G-2), that asks if I want the digital zoom on or off. I am embarassed to say that I DON"T KNOW!!! Any thoughts as to when I should use the digital zoom. Thanks for yur help. I've learned a lot reading these message boards.
Respectfully, Paula
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Old Jan 29, 2003, 8:56 PM   #2
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Digital zoom off: normal mode, the pixels on the whole CCD surface are on the final picture
Digital zoom on: from the CCD, the camera software crop out a small area, which make you think it's a bigger picture, but from a smaller number of real captured pixels; you can also do this yourself with a pic editor later.

So, set digital zoom off, you can always blow out and crop your pic later ...
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Old Jan 30, 2003, 8:29 AM   #3
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For your sharpest setting on zoomed pics, leave digital zoom OFF. If you leave it ON and try to manually select the top range of your optical zoom, you may accidentally spill over into the digital zoom range. I'd only use digital zoom for a non-critical subject, such as the license plate of a car.
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Old Jan 30, 2003, 11:42 AM   #4
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KCAN and LG are right; however, if you are definately going to crop the images you take (eg at a sporting event where your zoom is just not enough) the digital zoom will do it for you in camera basically. The difgference is that with it you save disc space, as you only use the smaller image. I have only used it in situations where i am away from any download source, with little memory left and longer zoom requirements. Otherwise turn it off, so it does not get used automatically.
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Old Jan 30, 2003, 11:59 AM   #5
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Digital zoom OFF. Having tried both options I believe that you get better quality post processing in Photoshop than you'll get using a digital zoom.
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Old Jan 30, 2003, 5:53 PM   #6
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Thank you all for your help. I understand now and appreciate your answers.

Paula
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Old Jan 30, 2003, 6:14 PM   #7
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Hi Paula,


I agree with most of what the other photogs here said.

However, I would leave digital zoom on if shooting
action.

Yes, you can post process optical full zoom to mimic
the digital zoom but it gives you an "instant option"
to capture more if you have it available.

It should give you fairly good images given you have
a 4 megapixel camera .
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Old Jan 30, 2003, 6:18 PM   #8
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Just being a bit of a devil :twisted: :twisted: , but if the cam is digital zooming on an uncompressed image before it creates the JPEG file, wouldn't you expect the result to be better than doing zoom in post after compression? Same applies to crop, might not in-cam crop before save, be totally lossless, whereas some editors are cropping lossy on compressed images?
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Old Jan 31, 2003, 8:47 AM   #9
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voxmagna may be right: i know hat the oly5050 shoots raw allways and then saves as jpeg. If the digizoom crops in raw, it should give better results.
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Old Jan 31, 2003, 8:40 PM   #10
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The question seems to be whether the ordering of transform operations is important when there is a lossy process in the mix. i.e., whether;

Original image => crop-interpolate => JPEG compress.

is or is not equal to

Original image => JPEG compress => crop-interpolate.

----------

Wouldn't digital zoom (crop-interpolate) followed by JPEG compression be a double hit in image quality?

First hit would be due to the camera's interpolation (rezing up) of the cropped image to a (larger) pixel map equalling the full image pixel size of the camera...

Followed by the quality loss due to JPEG compression. This time the quality loss is a loss of quality of an input image that has already suffered degradation from the interpolation algorithm.

It seems to me that the lowest total end-to-end quality loss would come from performing the interpolation in post processing. My reasoning is that the lossy JPEG (Discrete Cosine Transform) operates on the original, image (highest quality). There would not be any interpolation artifacts going into the compression process to exacerbate the loss of image quality. (sort of the garbage in => even nastier garbage out concept).

Just a thought.
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