What has to be emphasised is that Alamy doesn't care whats in your
pictures. From dog poo to celebrities - anything goes. If you think
somebody, somewhere might some day need that image - go for it. But on
the other hand, Alamy insists on digital excellence, so that a picture is
not rejected by the customer because of perceived faults. That means
that there are a few areas that are strictly no-no. These are:
Soft or lacking definition (SoLD). Because of the anti-alias
filters on our sensors this is always controversial. Alamy knows the
difference between that phenomenon and ever-so-slightly out-of-focus or
slight camera shake. As an example of what can happen here's a story.
Six months ago I bought new an Olympus EPL-1 micro four thirds camera,
complete with kit lens at a really good price. But I noticed that I was having to reject more
than a few images due to SoLD. I reckoned that this couldn't be down to
camera shake by me when I checked the IPTC data - my speeds were high
enough, my f stop was f7.1, as always. I dug and dug on the Interweb and
finally came across a site which had also found this and went to the
trouble of testing three individual lenses. They discovered that the
construction of the lens caused a wobble if used between 1/100 and 1/200
sec and thereby imparted camera shake to the image. The shake was
really miniscule but to the trained eye (as in Alamy) it was noticeable.
I bought a third generation lens at the same price as the original
entire camera and the problem was solved. The manufacturer has never
owned up to this fault, DPreview never caught it but it was noticeable
when the image was forensically examined at 100%. You can be sent to the
submitting sin bin for a month by Alamy for a number of SoLD
submissions. Ain't worth it.
No sharpening should be applied to an image, except perhaps for the default Photoshop RAW processing. And sharpening artifacts can occur by other means in the
processing, such as over saturation or colour removal at the Tif stage.
I only use the lens' "sweet spot" when shooting. Each lens on a 35mm
style digital camera has a particular f stop at which the lens is
sharpest, usually f8 or thereabouts, due to refraction
within the lens. This is, in my opinion, extremely important. So much so
that my aperture setting is permanently set and the ISO setting at Auto
for non-studio shots. My cameras are very good at noise - up to 1600
ISO is no bother when the exposure is good. (Nikon full frame 12MP D700
being the other camera). If I have a depth of field problem in the studio, I take a
number of shots at different focus points and depth of field blend them in PS to
achieve sharpness throughout the image, such as in this one:
Chromatic Aberration: All lenses give this to a greater or
lesser degree, some saying that more expensive and prime lenses being
better. Has to be removed. There are various tools and methods, which
I'm sure you know. I tend to use Replace Colour , if necessary selecting
the areas, so as not to damage other areas where those colours are
integral.
Dust and smudges: You know all about this, but just to
remind. Forensically examine the image at 100%, section by section, side to side
and up and down and clone out any that exist. If there are real things in the image that could be
construed as dust, remove them. I know one guy who shot an antelope on
light coloured ground on which stones were scattered, and it was
rejected, much to his indignation. Birds in a sky are a famous example.