First pics with the 50 1.4.

No can't see any halos at all. The smearing on the background is the pine kitchen unit it was taken against. Maybe should invest in some decent backdrops, seem to be plenty on ebay.
Uploaded the original jpeg just to see if the problem is the compression; (converted from raw) (warning 4Mb download)

http://www.bobmcgee.com/images/pentax/IMGP1920.jpg

If you're into monitor calibration - and I suppose we all should - I bought one of those spyder2 pro thingys off ebay and it works great.

Looking at this big pic, shows up loads of tiny imperfections I should I suppose have got rid of - tiny dots on the petals and a few marks on the stalk. Starting to get hyper critical of my own stuff which I suppose is good.
Just like to say thanks here for all the time and effort people take on this forum to be constructively critical of our newbie efforts - it means a lot.

For flower photography (and other small items) you'll find that full-size backdrops are unwieldy, expensive and complete overkill. Your best bet would be to go to your local art/stationary shop and buy single sheets of thin A3 card in all the colours you want. About ten pounds should get you enough sheets to cover just about every colour of the rainbow and they're easy to use, highly transportable and should suit pretty much any occassion you care to shake a stick at.

In addition to the cards themselves I also carry some assorted clamps that I bought from B&Q and blu-tack - voila! A cheap, flexible mini studio and enough change from a £20 note to buy yourself a drink to celebrate...

with careful lighting and a little photoshop/corel your computer monitor can be use as an infinately creative backdrop for macros.
added bonus for laptop/lcd users? It's polarized!

glue a greycard to a clipboard, and use watercolor papers that you've painted and some white an black cards to create a portable backdrop/reflector kit.