3, 4, 5, 8 MP 8x10 printout comparison - Long

Curious about just how many megapixels you need to get a
good 8x10 print, I did a test. I went to
http://www.steves-digicams.com and downloaded a similar
image from his samples for four different cameras. The
cameras we

3mp Canon S30
4mp Minolta Dimage Z2
5mp Canon S60
8mp Nikon 8700

The images were pictures of a shelf in Steve's house
containing some photography magazines, an M&M candy
statue, a barometer, an orangutan poster, and some other
things. The photos were not identical, but are very
similar.

I loaded up each image in IrfanView and printed each at 8x10
size on a Xerox Phaser 7700. The Xerox is an office printer
that is definitely _not_ photo quality, but it still gives a
useful color print.

I examined the photos on a CRT screen, on the paper
printouts, and on the printouts with magnifying lenses. For
whatever they're worth, here are my impressions:

3 mp.
I own a 3 mp camera and had always been satisfied with
the 8x10's I printed from it. Looking at the printouts
from two feet away, they looked fine. It was only when
I looked at the other printouts that I realized how much
the 3 mp was missing.

Specifically:
The larger object in the image that has little or
no fine detail (the M&M statue) looks very good,
probably about as good as with the other cameras.

However the fine print seen on the Ozium can and the
Digital Camera magazine spines is readable, but not
sharp and clear. Was the Ozium can not in perfect
focus? My guess is that the focus may not have been
perfect, but the low pixel count was contributing to
the lack of sharpness.

The finest print on the barometer is not readable
either on screen or on the printout.

4 mp.
To me, this looked better than than the 3 mp image, but
there was still room for improvement.

The fine print on the Ozium can was definitely
sharper than on the 3 mp image. The spines of the
magazines were slightly sharper, but still not
perfect.

The fine print on the barometer was still not
readable, either on screen or on paper.

Even from 2 feet away, the image looked clearer than
on the 3 mp camera, though only in the fine detail
areas.

5 mp.
To my eye, the 5 mp image printout looked very good.

The can and the magazines were sharp and clear. I
thought the difference was noticeable in comparison
to the 4 mp.

The image of the digital barometer was clearer on
screen than the others. The barometer part of the
printout also looked better, but only slightly
better than for the smaller pixel count cameras.

From two feet away, the image didn't look much
better than the 4 mp. If I looked at the details
closeup and noted the differences between the
images, I could then detect those differences from
two feet away. At a casual glance, I did not notice
the differences.

8 mp.
To me, the 8 mp printout looked only very slightly
better than the 5 mp printout.

The Ozium can and the magazine images were both very
sharp and clear, but I had to look very closely to
see any difference between it and the 5 mp image.

The characters on the barometer looked slightly
contrastier and better defined than on the 5 mp, but
only slightly so.

From 2 feet away, it was hard for me to say that the
8 mp image was better than the 5.

On screen, the 8 mp image was much better than all
the others. This tells me that there is detail in
the 8 mp image that is lost when printed at "only"
8x10. An 11x14 or 16x20 image would probably show a
significant difference as compared to the 5 mp
image.

Conclusions:

3 mp:
To my eye, the 3 mp camera is more than adequate for 4x6
and 5x7 printouts. It is adequate for 8x10s, and
possibly even 11x14s, but only for images in which fine
detail is not crucial for a good view of the subject.
For example, portraits and landscapes, especially when
mounted to be seen from more than two feet away, would
look quite acceptable to me.

If what I want is fine detail, for example to read the
signs in the shop windows of that street scene one
shoots on an Italian vacation, 3 mp is not enough.

4 mp:
4 mp looks better at fine detail. For me, I believe
it's probably worth the extra money to buy.

5 mp:
5 mp looks better still. If I could find a reasonably
priced camera that had 5 mp plus all of the other
features I wanted (like a long zoom), I'd be willing to
pay more for the 5 mp over a 4 mp camera. If I found a
4 mp camera that had all the features I wanted but
couldn't find a 5 mp with comparable features without
paying a much higher price, I'd be tempted to go with
the 4 mp, or maybe to wait for prices on 5 mp cameras to
come down.

8 mp:
For my purposes, looking at images on screen and
printing at up to 8x10, 8 mp seems to be overkill.
Extra money paid for the camera wouldn't return
noticeably better prints at 8x10 or smaller. If I
wanted bigger prints or wanted to be able to crop an
image, 8 mp would be worthwhile. But if I don't need
that, I don't need 8 mp.

Of course if 8 mp didn't cost any more ..., but it does.

Finally, I should note that I am not a professional
photographer, and certainly not a graphics arts person. At
one time I would have called myself an advanced amateur
photographer, but now I'm just a guy who likes taking travel
and family photos. I'm also 58 years old and my eyes may
not be as sharp as those of a 20 year old. So as we always
say, your mileage may vary.

Alan