RichA wrote:
On Oct 24, 1:37 pm, "David J Taylor"
-this- bit.nor-this-bit.co.uk wrote:
RichA wrote:
On Oct 24, 11:33 am, "David J Taylor" -
this-bit.nor-this-bit.co.uk wrote:
RichA wrote:
http://www.dpreview.com/reviews/canoneos40d/page26.asp

.. as would be expected simply due to its weaker anti-aliasing
filter.

David

That's what the site speculated caused it. Good thing is, of the
shots someone will take, it is likely few will be effected by a
slight increase in moire, but all will benefit from an increase in
resolution and sharpness.

No, it's false sharpness. Once the higher spatial frequencies have
been aliased down to lower, more visible frequencies, no amount of
post-processing will remove the damage done without causing serious
degradation of the image. It can also be one of those subtle effects
where you look at an image, and know something is wrong with it, but
can't quite put your finger on it.

Just say "no" to poor anti-alias filters!

David

How do you know the sharpness is "false?" If more real detail is
visible, it isn't just a ragged contrast effect, it is higher
resolution.

If the sharpness is achieved through having too weak an anti-alias
filter - it's false. The effect will be that the higher spatial
frequencies are aliased down to the lower ones, and this is most easily
visible on patterned objects, as you know, creating rather nasty artefacts
in the image. Sharp edges (perhaps what you are describing as detail)
will be aliased in exactly the same way, creating an artificial, rather
unpleasant sharpness to the image. Something your eyes and brain may tell
you isn't right.

If you like that effect, so be it. Optical anti-alias filters, unlike
those in the audio world, are not near-perfect, so you need to decide for
yourself what is "good enough".

Cheers,
David