Post by -oo0-GoldTrader-0oo-How important is the lens on a digital Camera?
Depends. Generally speaking, the better the lens the better the picture.
In film photography, where the resolution of some available films far
exceeds the state-of-the-art in lenses, and where most films are good
enough to tax any zoom lens, this is certainly the case. In Digital
cameras, most lenses are slightly better than the resolution of the
sensor or "digital film" Most Digital cameras have lenses that are
certainly good enough for their more-or-less fixed resolution, but there
are exceptions. Philips sells a 2 megapixel keychain or "lipstick"
camera called the KEY10 for about US$150. This tiny, fixed focus camera
looks to be the ideal cary-anywhere camera. Its small, light,
uncomplicated and 2 megapixels should result in a 1600 X 1200 pixel
image. My first Digital camera, a Nikon Coolpix 800 had this size sensor
and it was more than adequate for most purposes. Unfortunately, for
Philips, when they upgraded the 1 megapixel KEY07 to the 2 megapixel
KEY10, they "forgot" to upgrade the lens. The result is a very soft and
mostly useless 1600 X 1200 picture. So it is possible for a digital
camera to have a poor lens.
Post by -oo0-GoldTrader-0oo-Don't you need a SLR lens like a 80 to 200 zoom to get great pictures?
That's like asking "Don't you need a 4000 square foot house to get
proper heating?" In other words one thing has nothing to do with the
other.
First of all, the focal length of a lens only refers to it's field of
view, NOT the lens' quality. All things being equal, 80-200 on a 35mm
film camera is a mild to medium magnification telephoto lens. This same
focal length on a 21/4" X 2 1/4" (also called "medium format") camera
such as a Hassleblad would only be normal (80mm) to mild telephoto (I.E.
a portrait lens).
Secondly the CCD devices that digital cameras use in place of film to
capture the image are almost ALWAYS smaller than a frame of 35mm film.
That means that the lens focal lengths that most of us understand don't
mean very much in a digital camera. For instance, a Minolta Dimage 7Hi,
has a zoom lens with a focal length of from 7.2mm - 50.8 mm. On a 35 mm
camera. this lens would be an impossibly wide angle lens on the low end
and a normal lens on the top. But because the Dimage has a very small 6
megapixel sensor (about 1/4 the size of a 35mm frame of film), this
7.2-50.8 mm lens actually has the same coverage as a 35 mm camera's
28-200 mm lens!
Some of the higher-end digital cameras such as the Nikon D70, look like
35mm cameras and are even the same size as one. This is done mostly so
that photographers don't lose their often substantial investments in
35mm lenses. My D70 will fit and can use any of the autofocus lenses
that I bought for my Nikon F5 film camera. The problem is that the 35mm
form factor of the camera is misleading. The camera might look like a
35, it might fit and use interchangeable lenses for a 35, but, again,
the actual sensor size is smaller than a 35mm film frame. This smaller
frame makes the resultant picture look as if it was taken with a longer
lens than was actually used. For instance, the zoom lens that comes with
the D70 outfit is an 18mm to 70mm. Yet, because of the smaller-than-35mm
CCD chip size, this lens focal length has to be multiplied by 1.5X in
order to get the REAL, or working focal length. In other words, this
lens would be an 18-70mm on my 35mm F5, but on my D70, it's really the
equivalent of a 27-105mm lens. Oh, yes, and while I can fit my Nikon F5
lenses to my D70 (my 28-105 becomes a 42-157.5 and my 80-200 becomes a
120-300), if I put my D70's 18-70 on my F5 film camera, I get a black
circle in the middle of the photo with a picture in it. This lens was
designed for a digital camera so they didn't make the lens with any more
coverage than was necessary to fill the Digital camera's CCD! Since
lenses are always better quality in the center than on the edge, you
will always get a better lens by buying a wide-angle lens for a film
camera to use on your digital camera. A full-frame 18-70 designed for a
35mm FILM camera will have the edge of the lens far outside the coverage
of the sensor, thus throwing the softer edge of the lens away. Had I
known this when I bought my D70, I wouldn't have bought the 18-70mm lens
that came with the camera/lens outfit and purchased just the camera
alone.
So you see, focal length is relative, while lens quality isn't. Good
digital cameras have lenses which are more than adequate for their task.
The actual focal length is irrelevant as different manufactures make
different size CCD chips in any given pixel count. This said, you cannot
go by the actual focal length, but rather the 35mm EQUIVALENT focal
length is all that's important. Like I said, in the 6 megapixel Minolta
Dimage 7Hi, 7.2mm is equal to a 28mm wide angle film camera lens, but on
my 35mm -sized, 6 megapixel Nikon D70, 18mm is equal to a 28mm
wide-angle lens because the Nikon 6 megapixel digital sensor is larger
than the 6 megapixel digital sensor in the Minolta. The Minolta is a
much smaller. lighter camera than the Nikon D70 because of this, but
then the Minolta's lense is permanently attached to the camera and not
interchangeable with the lenses of one's 35mm camera.
Make sense?
--
George Graves
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Knowledge is good.