I would set that to 0 or -1 if I were you - you can always sharpen later, whereas you can't so easily undo the effects of over sharpening.

Wikepedia has a sensible article

http://en.wikipedia.org/wiki/Chromatic_aberration

CA is clearly a lens issue

PF seems to be a combination of sensor and lens design issues

Sea also

http://en.wikipedia.org/wiki/Purple_fringing

I think this is a fairly natural light... Taken at 14:49BST so nowhere near sunset...
*ist DS, 18-55 @ 55, F22, 1/1500s 200ASA - hold camera well away from eye, line up vewfinder, shoot and hope for the best. Bit of post procesing in Photo Lab 3 & Paintshop Pro. (just histogram, gamma and dust removal!)

I like the compositions, especially the Victorias Rifle Bird. The colours in all the pictures seem a little muted to me, a bit of judicious tweaking of contrast and saturation would not hurt.

You can tell the first one is an older lens - the puple fringing is rather pronounced!

The point of focus on the stone curlew is a bit too far forward - the leaf on the ground is in focus, as are the tail feathers.

Not that I am in much of a position to comment - I have very few wildlife photos with which I am genuinely happy. It is quite a challenging task to get everything to come together - and I can't blame my kit any more!

Venice 24/10/06 *istDS DA18-55 @31mm ISO400 f8 1/180

Try a reflector (e.g a sheet of white card) underneath (and just out of shot of course) to soften the shadows - I did that with my orchid shots

The problem is we need some form of 'standard' by which to compare the FOV of cameras with different size sensors. Maybe it should be the diagonal angle of view in degrees or (if it was desirable that longer focal lengths give bigger numbers) 180/diagonal angle of view. Both of these would be logical but would need the industry to decide on a standard which about as likely as flying penguins...

So we are probably stuck with 35mm equivalent for a while yet. Having used 35mm since 1984 that is fine by me...

Thanks for the comments - I partly put them up because I was so impressed with the performace of the lens at f2.8 and the ability to turn it into a macro with a simple close up filter. The flower heads are about 5cm across to give an idea of scale.

I have to confess to having tweaked the saturation up a bit - though keeping a close eye on the highlights in the colours to make sure I don't blow them - or at least more than one at a time! (its no more than using Velvia and a polariser in film really...)

Having had to come back to England light, I have only my old *ist DS (borrowed back from my sister in law), the Mk 1 18-55, and a newly acquired SMC A 135mm. What a lens! Here are a couple of pictures using the 135 of an Orchid, the first at f 2.8, the second with a +3 closeup filter and at f9.5. Shot in Raw, processed in Pentax photolab 3, and finished of in PSP X2

Actually I sometimes just right click, copy, then in PSP X2 use the "paste as new image" option.