Posted:
Tuesday, November 25, 2008
Beware
the Digital Camera Megapixel Myth!
Why Cameras
With More Megapixels Are Not Always
Better Deals
Advancement
in the digital camera and camcorder
industry has slowed in recent years.
Although manufacturers continue to
refine their product lines, the increase
in the number of megapixels a digital
camera contains does not always
translate to better quality photos.
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Most
professional photographers are aware of
the many factors that go into the
purchase of a quality digital camera.
But to the casual consumer and
especially the budding amateur
photographer who may want to turn pro
someday, the megapixel myth is important
to recognize if one is to get the best
value for his or her dollar.
In recent
years, manufacturers and retailers have
emphasized the importance of the total
number of megapixels a digital camera
contains. But in an ocean of
specifications, one of the most
overlooked is the size, not the number,
of pixels on a camera's sensor. Bigger
sensors usually mean bigger pixels,
which provide some advantages when it
comes to making an image.
A digital
camera sensor can best be compared to a
flat sheet of material upon which
millions of tiny cubby holes rest, sort
of like the cylindrical holes of a
honeycomb. Each of these cubby holes is
known as a “pixel” and the fact that
millions line a digital camera sensor is
where the term “megapixel” originated.
So a camera with 5 megapixels contains
about 5 million of these tiny cubby
holes that are each responsible for
detecting light.
Light
particles, known as photons, pass
through a camera's lens and are captured
by the pixels on the sensor. Each pixel
is capable of detecting either red,
green or blue light. Together, these
three colors combine to make up all the
possible colors on an image. The more
photons a pixel catches, the brighter
that pixel’s color. Pixels that fail to
catch any color record black whereas
totally full pixels record white.
Here’s why
it’s often not worth paying more for a
camera that simply boasts more
megapixels.
Larger
pixels (cubby holes, remember), with
larger surface areas, capture more
photons per second, which means a
stronger signal. This translates to
less noise and cleaner colors in the
resulting image. Bigger pixels can also
capture more photons per exposure
without filling up, so larger pixels
hold on to their color longer and don't
go white as quickly as smaller pixels.
The reality
is that sensor sizes in compact cameras
haven't gotten much bigger. But their
overall megapixel count has. The only
way to accomplish this was to shrink the
size of the individual pixels. This is
why it's often not worth paying extra
for the newest digital camera models,
especially if the only difference is an
increase in pixel count.
In fact, it
becomes more and more difficult beyond 7
and 8 megapixels to notice a difference
in overall picture quality. Again, this
is because the overall size of the lens
is the same.
This trend
is not limited to point-and-shoot
cameras. It is also true for digital
single-lens reflex (dSLR) cameras.
In our tests, we concluded that the new
15-megapixel Canon EOS 50D produces more
noise and slightly less dynamic range,
than the older 10-megapixel Canon EOS
40D. The 50D sells for around $1,400
with an
EF 28-135mm
lens while the 40D commands about $1000.
That’s almost a $400 difference.
Some other
cameras worth looking at are the
Canon Rebel XSi ($600), Nikon D200
($800), Nikon D80 ($640), and Nikon D90
($1,000).
Larger
sensors also allow photographers to
produce images where only a relatively
small portion of the subject is in
focus. Cameras with small sensors tend
to produce images where almost
everything appears to be in focus.
While it may be great at a party to
capture a large group of people in
focus, it is usually less desirable for
a portrait photographer when the images
are of closer proximity to facial
features.
This is
primarily why in normal shooting
situations, images produced by dSLR
cameras look so distinct over small
point-and-shoot cameras. These effects are similar
to digital video footage when comparing
grainy quality from a lower-end
camcorder with superior, crystal-clear
quality from a professional high-end
camcorder.
It’s
probably wise to use a dSLR if you need
to produce a really shallow depth of
field. But you can achieve this with the
cheapest of entry-level dSLRs, which are
also relatively small.
Some good
cameras recommended by professional
photographers on a budget include the
Canon Rebel XS (around $510 with lens),
Nikon D40/D40X (around $450 with lens),
and Olympus E-420 (around $460 with
lens).
So don’t get
caught up in the megapixel myth. The
number of megapixels has become more of
a marketing gimmick aimed at fooling the
less experienced photographer. Rather
than pay top dollar for the current
model simply because it offers more
megapixels, you might go for a little
older model and spend the difference on
accessories.
Of course,
the biggest factor in producing
professional images is the photographer,
not the camera. So if you’re in the market for
a new camera, it makes sense to do your
research and read what others are saying
about what works for them.
About
the Author
Jeff
Duncan has been a photographer since
1991. He specializes in children's
portrait photography and has managed his
own business since 1996. He and his wife
Sheila have three children and work out
of their home in suburban Detroit.
