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Old Sep 23, 2006, 5:05 PM   #31
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A bit more on the question of print size:

Printing is generally done at 300dpi. That's 300 dots per linear inch; a sqaure inch therfore has 300*300=90,000 dots. An 8" by 10" print is 80 square inches. So at the optimal resolution (1pixel for each "dot"), an 8x10 print is using 7.2 MP (80*90,000).

Therefore a 10MP image would have no advantage at all over an 8MP image for the purpose of an 8x10. Both will be reduced to 7.2MP of actual data in the printing process anyway. And a 6MP image, at 83% resolution, would be still quite sharp. Things will start to get a bit flat by the time you're down to 50%, but still look quite good up above 75%.

For an 11"x14" print, on the other hand, the optimal size would be 13.86 MP. In this case, the 6MP image is only about 43%, the 8MP is still good at 58%, and the 10MP probably quite sharp at 72%. For a 16x24 poster, you would want to shoot at 30MP if that were possible, just to get to 75% (since it's not, you might explore large format film). Bottom line--if you are regularly doing very large prints, you want as many MP as you can afford. But if you're not going over 8x10, you might not even notice the difference.

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Old Sep 23, 2006, 6:18 PM   #32
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Thanks for the info. I knew there was a way to figure that, but wasn't sure.

I took a look at a Pentax K100D and a Canon EOS Rebel XTI earlier this afternoon. The Canon is impressive, the lenses for it (roughly a 70-300) was around $160 or so, $200 for the Pentax one.

Took several at ISO 1600 (inside the store, with & without flash), both seemed to work just fine. I was impressed with both.

The Canon was a 10 megapixel - very nice, and would be around $1100 with the lens I want. The Pentax was $699 + $200 for a similar setup.

Been reading the reviews for both.......

Anyone here have one/both or have looked at each of them?

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