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Old Feb 11, 2005, 4:32 PM   #1
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We all know to avoid using digital zoom because it deteriorates the picture by removing pixels, but just exactly HOW does it work? I've been told that about !/2 of the pixels are eliminated for each doubling of magnification, so, does this mean that the 28-200mm lens of the Pro 1, at telephoto, will take 400mm, 4 megapixel shots by using just 2x of the digital zoom? Of course I'm trying to figure out how to get more bang out of the camera, as it seems the ONLY 2 things missing from it are longer telephoto and image stabilization.

Also, I'm waiting for my Pro 1 to come in, just picked one up for $647.99 from Abe's. I think a lot of people would be interestedto read an updated review (summary)of this camerafrom Steve with the new firmware addition. I certainly would. It's one of the main reasons that pushed me over the top to finally purchase it.

Thanks for the Forum.
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Old Feb 11, 2005, 7:32 PM   #2
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My advice to you is to do tests... because yes digital zoom can be useful... The main reason why people don't like is because you take a picture of something which is already cropped(sort of), so you don't have the option to go back...

But once u get your camera and you do tests, you will be able to see how far you can go... for instance, with my A95, I did such tests and here are the results http://nicolas7894.fotopic.net/c418760.html

The results really isn't that bad... and I actually printed a picture taken at full digital zoom(4x digital) and printed it at 4x6 and it is very acceptable for me, so its really up to you IMHO.
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Old Feb 11, 2005, 8:53 PM   #3
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Nicolas,

Thanks for the reply, and I love the snow behind the fence, something we never see here in Lousyana.

But the same question remains. For instance, did the picture you took with a 5 MP A95 @ 2x digital zoom give you a 2.5 MP picture?

I agree that the bottom line is what's acceptable to the user,but I want toknow what's happening when I go into digital zoom, and how far can you push it.
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Old Feb 11, 2005, 9:13 PM   #4
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No, if you use 2x digital zoom, you do not divide the mp by 2.

First of all, what you need to know is that the number of mp remains the same, but actually its the equivalent of dividing by 4. Because you divide by 2 horizontally and by 2 vertically. So an 8mp picture with 2x digital zoom would become a 2mp picture.

Here is how you calculate everything

x = effective focal length(in mm) / maximal optical focal length

then, mp count / (x^2) = effective number of megapixels.
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Old Feb 11, 2005, 11:38 PM   #5
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What advantage is there (if any) of using the dig zoom, versus post processing cropping of the image? I would think as long as the original is focused well you should be able to crop significantly and still get good printable results with the Pro1 up to 8x10. I have cropped some shots on my S1 @3.2mp - the equivalent of a 2x dig zoom and printed at 8x10 with good results...
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Old Feb 12, 2005, 3:11 AM   #6
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Okay - want facts? Well, these are biased by Scotch, so be forewarned.

Analog zoom. The lens actually changes focal length. So something far away is magnified within the optical system from size 3 to size 21 (7x optical). The CCD still has 640x480 resolution (or 10,000x7500 if you paid for it). The amount of light may or may not be affected (f2.6 vs. f6.3 when zoomed).

The bottom line is that if optics do the mag, you still get 640x480 pixels of useful info.

Now, if we use digital zoom, we take the640 x 480 and zoom in on only those pixels. A 7x zoom means we take that 640x480 and reduce it to 90x60 so it looks 7x bigger (or there abouts).

What we really see with digital zoom is a small part of our original image. Any photo editor can do that - and probably do it better than a camera cam. So ignore digital zoom. It is a fallacy.

After a digital zoom to 7x, you get only 90x60 pixels of data versus 640x480 if the zoom were in the lens to begin with.



Read it another way - pay extra for digital zoom and you are the marketeers lacky and making that company lots of unearned money.




If you ever need digital zoom - use your photo editor and do a good resise based on good interpolation rules.







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Old Feb 12, 2005, 3:16 AM   #7
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From: Nicolas
Date: 2005-02-11 20:13:26
Reply: http://www.stevesforums.com/forums/reply.php?topic_id=47478

...you use 2x digital zoom, you do not divide the mp by 2.

No no no - digital zoom of 2x means if you started with 1000x400 pixels, you end up with 250x100 pixels of data. The resulting image is two times the original size, or 1/4 the original area.


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Old Feb 12, 2005, 8:52 AM   #8
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Agreed, my point exactly - there should be no need or reason for digital zoom - optical zoom is the real deal!
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Old Feb 12, 2005, 5:19 PM   #9
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TDM_Canon_User wrote:
Quote:
From: Nicolas
Date: 2005-02-11 20:13:26
Reply: http://www.stevesforums.com/forums/reply.php?topic_id=47478

...you use 2x digital zoom, you do not divide the mp by 2.

No no no - digital zoom of 2x means if you started with 1000x400 pixels, you end up with 250x100 pixels of data. The resulting image is two times the original size, or 1/4 the original area.

If you read carefully, you will have noticed that I said "you do not divide by 2... And if you continue to read further, you will see that I said that in fact you divide by 4, which is... the same as 1/4 of the original image.

With all that being said, digital zoom and cropping are basicly giving you the same results...
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Old Feb 12, 2005, 6:01 PM   #10
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Nicolas, TDM and Geeeyejo,

Thanks for the education. I most likely would throw a shot into Photoshop and crop accordingly to get what I want, but I just wanted a realistic idea of how far I could push digital zoom, if any, before I got to PS. I'm aware that we should never use it, I wanted to know exactly why.

And yes, I did decide to pay for those extra mp for a number of reasons. I took a shot of my family with my G5 in a living room around Christmas at 35mm. The camera was about 15 feet away, and the subjects stretched out about 16 feet or so wide. Well, the shot came out great.In fact, as I played with it in PS I noticed that it was actually one of the better shots that I had taken of my wife. But when I tried to crop and blow up a portrait of just her, the 5 mp shot fell apart. I'm assumingI didn't have enough resolution to crop that much.

I also like wildlife shots, say, at a zoo. But of course sometimes Mister Lion doesn't want to walk up and pose for your camera. I wanted the extra res so I could zoom as much as possible and still crop to get closer, right into his face. And I really don't want to carry around a bunch of lens, even though I know that there is a 2x teleconverter for the Pro 1, and a 1.7x that I believe Canon makes.

Interestingly enough, I almost made the decision to get the S70 AND the S1 to try to get the best of both worlds, but I thought I'd still be lacking at the telephoto end if I tried to crop a 3mp image.
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