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Old Oct 20, 2004, 3:30 AM   #1
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I need to be educated.

I see in the EXIF data 'X resolution' and 'Y resolution'...

I've tested a few cameras, and, as far as I can see, two of the cameras I've tested (Olympus C-740, Minolta Z2) have 72 for both 'X' and 'Y' resolution at the highest, largest, finest settings, as well as at the lowest, smallest,most 'unfine'settings.The Canon S1 IS has 180 instead of 72 at the highest, largest, finest settings, as well as at the lowest, smallest, most 'unfine' settings.I have downloaded sample photos of the Nikon 5700, and they are at 300. I've downloaded photos from the Panasonic FZ-20, and some photos are 72, while others are 200.

And so I am confused.

Now, I assume this number (72, 180, 200, 300, etc.) has something to do with DPI (dots per inch).

I suppose my questions are... Can this 'X'/'Y' resolution number be set by the user, or is it fixed within the camera? If it is fixed within the camera, why do photos from the FZ-20 show two different numbers for two different photos? (72 and 200)

I know that 300 DPI is considered 'proper' for printing. So, if I have photos from a 4 MP camera taken at highest resolution (2272x1704), and want to print a 6x4 inch photo, I'm at around the 400 DPI range, right? What does the 'X resolution 72', 'Y resolution 72' mean, then?

I apologize for not explaining this as efficiently as it should be explained... but my deficient understanding of the circumstance prevents me from offering a better explanation of that which I wish to resolve.

Many thanks to anyone who can aid my understanding of the issue here.
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Old Oct 20, 2004, 5:16 AM   #2
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Old Oct 20, 2004, 5:20 AM   #3
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Until you get to printing, this number is really meaningless. 72dpi is a left over from the original Mac days, but an image will be taken and displayed the same way on a monitor whether it has a dpi of 10, 100, or 1000, becuase the image would still have the same number of pixels across and horizontally (say 1600x1200).

But when I go to print, that 1600x1200 prints different sizes depending on the dpi assigned to it, or if it's changed through the resizing option in photo editing software. For example, using that 1600x1200 dpi the way the camera took it at 72dpi:
At 72dpi it prints a 22.2x16.6"
At 180dpi it prints an 8.8x6.6"
At 300dpi it prints a 5.3x4"

That's the relationship. In my case with my 2mp camera that's what I get (which is enough for me for now). With changing it that way you aren't adding or subtracting information from the image itself, merely telling it how to print with the information already in the picture.
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Old Oct 21, 2004, 2:38 AM   #4
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Thanks to both of you.

I believe I am beginning to comprehend the matter. Sure is more complicated than photography used to be.

I figure, with any luck, I should understandthis resolution stuffcompletely byApril or so.

Thanks again.
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