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Old Jan 15, 2005, 9:48 AM   #1
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Sorry if it's a silly question:

If I take a zoom shot with the 4 mp, 10x optical Olympus C-765, how would it compare to the 7 mp, 4x optical Sony DSC-V3 equivalent photo, if I were to use software to blow the Sonyimage up on my PC?

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Old Jan 20, 2005, 10:26 AM   #2
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I must be misunderstanding something in your question....

The Olympus is 4MP, the Sony is 7MP.

What you're talking about here is cropping, not "blowing up" the picture, and that's a very important distinction.

"Blowing up" an image requires -interpolation-, using software that "guesses" what the needed additional pixels might be. Now, some interpolation algorithms are pretty good (Photoshop, for example), but nothing compares to viewing or printing the original pixels.

Now, I generally opt for more pixels... in fact, I opt for more pixels in virtually every case. Why? Because if I have more pixels, I can crop, which gives you the same effect as a zoom. However, with a crop, you're still working with the original pixels, just fewer of them. In my experience, an image that is not interpolated is almost always cleaner and more accurate than one that has interpolation. And having more pixels gives you the ability to "zoom" after-the-fact without losing quality.

The downside is that, depending on how much you crop the picture, you may not have sufficient pixels to "blow up" into a large image (say, 16X20) if that's what you intend to do. On the other hand, not every photo wants or needs to be a wall mural!

There's an even more important factor - the quality of a zoomed image depends, more than anything else, on the quality of the lens. There are many variables at work here. However (and it's just my personal experience), having the ability to crop effectively (meaning you have pixels you can afford to lose) seems to be a better option than getting closer to your subject with many fewer pixels.

Just my opinion, of course :-)


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Old Jan 22, 2005, 11:15 AM   #3
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Years ago, the old Sony Mavica FD-91 had a 14x zoom which was the equivalent of about 518mm in 35mm. (The FD-91 was alsothe first digital still camera to have image stabilization.) but it was only around .8Mp...UNDER 1 Mp.

In those days (when cameras were just beginning to appear with 3Mp sensors but only 3x zoom), people were asking the same question. Does the huge optical zoom of the FD-91 compensate for the low resolution or does the extra resolution of the newer (3Mp) cameras make up for their limited zoom?

To answer the question definitively, two Mavica users developed the "Figure of Merit" calculation.


It provides a (huge) number that can provide an objective comparison between cameras with different size and resolution sensors AND different zooms.

The FoM figure for the standard Sony V3 is about 131 Billion (130,912,616,448

The FoM for the old FD-91 was 211 Billion (211,018,579,968 which beats the 7Mp V3!!!

If ypu add the 1.7x telephoto lens to the V3, the FoM jumps to 378 Billion (378,337,461,535) which passes the FD-91's 14x zoom!


The FoM for the standard C-765 is 566 Billion (565,622,886,400) which beats them all!

So, for maximum zoom shots, the Olympus will be able to put more pixels onto the scene than you are going to be able to get by zooming with the V3 and cropping!

However, that is ONLY for maximum zoomed shots. AS you back off the zoom, the V3 rapidly overtakes the C-765 just due to resolving power.

I know this has been a really technical discussion but it does serve to finally resolve the issue of pixels versus optical zoom.

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Old Jan 22, 2005, 6:13 PM   #4
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Meryl Arbing wrote: I know this has been a really technical discussion but it does serve to finally resolve the issue of pixels versus optical zoom.

Very good explanation!
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