Can you please check that URL, I get an error message.

Absolute resolution is a measurable quality and can make a noticeable
difference that may not be difficult to detect in direct examination of a
film negative or transparency.
Not so much with digital capture media and processing, particularly when the
evalution is made from a processed image viewed through an unselected
monitor under unknown conditions.
It would take drastic differences in lens sharpness to see distinct
differences in complex digital images that are otherwise created and
processed under identical circumstances.
The truth is that those drastic differences in sharpness between very
expensive lenses and more moderate priced lenses do not exist for practical
purposes. The differences in quality between expensive and moderate priced
glass is even less visible in a well crafted print than it is in an enlarged
subsection of an image on a computer monitor.
Rather than opine on these subjects readers of this newsgroup should perform
these comparison tests themselves using their best glass and more moderately
priced glass using digital capture media and optimally processed prints as
the final object. Comparisons between a Lensbaby and a Leica are not the
point, but lenses of the quality that ukbrown has compared are the type that
should be compared.
If you convince yourself you can consistently see a difference award
yourself a hot steaming boquet of bokeh.

If you zoom in on the UPC code label, you can see the number of pixels that
the black bars fade to white over.  This is virtually identical between your
18-55 and 24-105mm lenses.

What your pictures show is just how good optically the 18-55mm lens is.  It
feels cheap, looks cheap, is light and small, but optically it is
considerably better than people give it credit for.  You have to spend a lot
to get better image quality.  It's not like the old 28-80 and 28-90 kit
lenses that Canon shipped with most of the film SLRs.  It is a lot better.

If you work around its limitations, rotate your polarizer or ND grad filter
after focussing, stop down a little, fix the CA with Adobe Camera Raw etc,
you can get very good pictures from the 18-55.  Unfortunately Canon charges
you extra for the hood for this lens.  Canon does put some good design into
the 18-55mm lens though.  It has a circular aperture and one aspheric
element. It also has a fairly large image circle compared to the other EF-S
lenses (except for the 60mm macro).  With a 12mm extension tube, I have
mounted it on a Canon Elan II film camera.  There is enough coverage above
20mm for the full frame.  Of course the coverage would be less without the
extension tube.  At 18mm the corners have visibly darkened on a film camera.
This may explain the fairly low light fall-off for this lens compared to
others.  I also like how it sort of self centers at 28mm (normal focal
length for the XT).  The 18-55 can suffer from bad ghosting flare if a UV
filter is fitted and there are point light sources within the frame or very
close to it.  It is important to remove the filter for these situations.

What you are paying for with your 24-105 mostly is a larger image circle,
better build materials and quality, weather sealing, much more glass (F/4 at
105mm needs a 26.25mm clear aperture compared to 9.82mm for f/5.6 at 55mm),
the image stabilizer ($$), internal focussing silent USM focussing motor,
metal lens mount, distance scale, larger range, included hood, 3 aspheric
elements, super UD glass, non-rotating front element etc.  These are all
good things and worth the money, but as you have seen, you didn't buy much
more sharpness.

The primary benefits of the 24-105 are in the convenience of use, larger
aperture from 31mm and above (the 18-55 is f/4 or better from 30 and below),
the image stabilizer which is fantastic and longer telephoto range.

The drawbacks to the 24-105mm are of course cost, weight, and size.

Don't get rid of your 18-55 yet.  It fits easily in a jacket pocket for when
you need a quick wide angle.

On 22-Oct-2006, "ukbrown@newsgroups.nospam" <ukbrown@newsgroups.nospam>
wrote:

Did a comparison test with another 24-105 lens, no better than mine and he
is very happy with his as it compares well with his other L lenses.  Thanks
for all the info and good advice here, much happier with my purchase now I
realise what I am paying the money for,  better quality at the extremes IS
and much better construction.

Regards

Tough to tell at this resolution and magnification,.   First, you have
shot a close up with a very shallow depth of field.  So the eye gets
fooled.  There is a very small plan of sharpness with much out of focus
becauese ot he aperature and distance to subject.

If you want to do a sharpness test, use a copy stand and shoot a flat
subject with fine lines at close range. Light it well to remove all
effects of noise etc.  Keep the camera film (or sensor) absolutely
parellel to the subject. Hold the subject as flat as possible.  Use a
remote release and mirror lockup if available..   Only then do you
remove enough of the other variables to really see what the lens is
doing.

Don't shoot pictures like that all the time?  Then, I believe, your
conclusions are correct.  Many great photos were taken with lenses of
much less quality than even some of today's mediocre lenses.

Jim     <jen....not....home..remvdots...@....yahoo