megapixels and larger prints

[Ballpointpenner]

As some of you know, I am currently on the hunt for a new DSLR. One thing that I would want from this camera is the ability to produce beautiful large prints from time to time. Naturally, this has a fair bit to do with megapixels. The cameras that I am looking for are 10, 12 and 15 megapixel machines. I would like to know what the differences between these three resolutions really are when it comes to printing.

DPreview offers "absolute resolution" and "extinction resolution" parameters in their camera reviews. Looking at those, I can see that, between 10 and 15 megapixels, the absolute resolution difference is rather small - perhaps 20% each way. The extinction resolution difference, however, is significantly larger. What precisely does this mean? Also, are they taking into account photoshop's photo-enlargement algorithms?

The above questions are quasi-theoretical, but I am at least just as interested in people's real-world, first-hand experience of megapixels and printing. I am curious if there are some among you who have found their camera's megapixel count to be a wall, such that you wanted to produce a picture of a certain size but could not due to your lack of megapixels? Also, for those of you who do print large - how many megapixels do your cameras have? How large do you feel comfortable printing?

Thank you for your time,

- Bpp

[TCav]

10MP: 3888 x 2592
12MP: 4272 x 2848
15MP: 4752 x 3168

At 300 dpi, that's

10MP: 13" x 8½"
12MP: 14¼" x 9½"
15MP: 15¾" x 10½"

And that's without the upsampling that's part of printing on every printer from every application.

[TCav]

It's also without cropping.

[Ballpointpenner]

Thanks for the quick reply, TCav. So, what would the consequence of this "upsampling" be? Also, your statistics suggest that even a 15mp camera is not suitable for printing nice quality 12 by 18 inch prints. Is this correct?

- Bpp

[TCav]

Originally Posted by Ballpointpenner

... your statistics suggest that even a 15mp camera is not suitable for printing nice quality 12 by 18 inch prints.

That's at 300 dpi. A 15MP image at 18" x 12" would still be at 264 dpi, whch is still quite respectable.

And taking a large image and upsampling it yourself, multiple times, each time in small amounts, can produce excellent results. Of course, the more you have to work with, the better the results will be.

[VTphotog]

I can make very nice prints of that size from my 6 MP camera.

brian

[Chato]

Originally Posted by VTphotog

I can make very nice prints of that size from my 6 MP camera.

brian

Quite right. For a 16x20 interpolating up should be considered part of the routine. And the printouts, viewed from a proper viewing distance are indistinguishable from a photographic print.

Dave

[TCav]

6MP: 3000 x 2008

At 18" x 12", that's still 167 dpi. That isn't bad.

It's important to remember that while the difference in megapixes may seem large, the difference in the linear dimensions isn't very much.

[Chato]

Originally Posted by TCav

6MP: 3000 x 2008

At 18" x 12", that's still 167 dpi. That isn't bad.

It's important to remember that while the difference in megapixes may seem large, the difference in the linear dimensions isn't very much.

A 12 meg sensor is only 50 percent larger than a 6 meg sensor...

Dave

[TCav]

Originally Posted by Chato

A 12 meg sensor is only 50 percent larger than a 6 meg sensor...

Yes, in much the same way that a kilometer is longer than an hectare.