It's because the limitations of the optical design...
If you have a lens that limits zoom range, it will not have as much
aberration than one which has a more complex formula.
If the mfgr's were to make a zoom that went from 28-200mm at the same
quality as one that goes from either 28-80 or 80-200, it would be heavy &
cost about 3 x's as much...
If you look at element design in optical systems, you'll see that mfgr's use
more elements & use trickery to simulate the wide & long ends of the zoom
range. The lens really doesn't become a 28mm lens (compare the element
design to a 28mm prime), but they shift a reverse element to make the angle
of view wider. This comes at a price.... The price - optical quality &
usually distortion & aberration. The same sort of reverse trickery is used
on the long end too...
Look at: [url]www.photodo.com[/url]
You'll see a rating system based on the lens' resolution & clarity factors
(MT). The MT ratings deduct points for curvature distortions & basic
aberration. Although MT isn't "everything" about lens qualities, it can give
you a better idea of how sharp & accurate a lens can be.
Other characteristics that are important in overall quality are: color,
contrast, booked as well as the MT...
Super zooms usually fall short in all of these areas. Try ing up a print
to 11"x17" using a good lens (like a Canon L series) & compare a prime 28mm
to a 28-70mm ( 28mm) & a 28-200mm zoom (also 28mm) & do some
You will probably see some differences at 4"x6", but the larger you print,
the more difference you'll see...
"Bob or Shelly Young" <bobandshellyev1.net> wrote in message
news:vfvmpjc0u3ga8bcorp.supernews.com...lenses?> I am kind of new at this and I was wondering why no-one likes 28-200> I have seen quite a few posts where they are derided, but I have not seen
> why. (Granted, I have not been reading this group very long.) I am not
> sure why lugging a 28-80 and an 80-200 is better than just using one lens.
> So what gives?
> Bob Young
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