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Old Dec 5, 2002, 4:04 AM   #11
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The difference in linear size between a 4 and 5 MP print at the same resultion will be 11% instead of 20 because the size varies with the square root of the number of pixels. (The pixels are measured in two dimensions combined, whereas the size is expressed with each dimension separate, as in 8x10.)

The highest quality prints are often printed at 300 dpi or more, but some processes do very well at lower resolutions, down closer to 225 dpi in some cases (lower if you're not too picky). You can calculate the size print you can get at a given resolution by dividing the pixel dimensions (e.g. 2272 x 1704 for a Canon G3, a "4" MP camera) by the dpi you want.

As Bill points out, your comparison in the shop really doesn't show much. The way the flash is set, as well as other settings you can control for each camera, will cause the differences you noticed.
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Old Dec 5, 2002, 7:44 AM   #12
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I have a 4 MP Canon G2 and have enlarged my 2272 x 1704 image in the best quality / least compression setting to a 16 x 20. This was a family group pix of 27 people and the results were acceptable to them and they ended up having it professionally framed. The printing was done by Pictopia outside of Oakland, CA on a Gretag Lightjet 430. Here is a quote from their website "Pictopia's LightJet 430 renders output at 300 pixels per inch (PPI) at 36 bits/pixel onto archival silver halide glossy or matte photo papers or Fujitrans transparencies. Output from a continuous tone printer such as the LightJet is about equal in resolution to 4000 dots per inch (DPI) on an inkjet, laser, or other halftone printer."

After reviewing my file, they recommended not going above a 16 x 20.

Hope this helps...Harvey 8)
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Old Dec 5, 2002, 9:21 AM   #13
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My 2c

How much difference will there be on a projected image from a 4MP vs. 5MP camera in an auditorium where the images are typically 30 feet or even larger. Certainly the resolution of the projector ...
Unless it's a slide projector or some souped-up Faroudja setup. Everyone here will be hard press to tell the difference between a 2-3Mpixels camera let alone 4-5M when it's projected! It's like listening CD through an AM station or watching a progressive scan DVD through a 3/4 RF modulator input. Most affordable projectors are specs much less:

Although the technology can yield impressive printers:
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Old Dec 5, 2002, 9:29 PM   #14
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8) Since the really knowlegeable posters here tend to be very technically inclined and savvy, I take their advice very seriously. They have helped me more than they know.

Still, sometimes I think we tend to over-analyze. Assuming a particular camera has very favorable reviews (key for me), I'll go with the extra MP's every time. I know that people actually make pretty good, big pictures out of 3MP cameras, but I need all the advantage I can get. For me that means lots of MP's. There is a reason they go to the trouble of putting those extra MP's in.

You know, I could do minor surgery, and there is a good chance the patient would survive, but I don't think it's a good idea.
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Old Dec 6, 2002, 4:33 AM   #15
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I think what we're saying is differentiation based on current Mpix offerings, gives small gains only noticeable at the higher print sizes.

But given a large jump from say 3 to affordable 6 or 8 Mpix, we would then be discussing other features important to getting good pics.

In the old days we moaned about film grain. Now standards are higher, more consistent and films can be made faster and still retain good grain we could be arguing about lenses and features in slr's - but film is less talked about, except amongst specialists.

Seems the same with digital. Once 10Mpix plus becomes the norm, other things might take on higher importance.
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