Hmm, I'm now leaning back towards the Tammy for a few reasons: one to do with my shooting style and the rest the lens itself
*) Sharpness
*) Build quality
*) All of the reviews (and I mean ones from photo sites, not magazines ) say that the Tamron's focusing ring is very good, and since I'm not brilliant at manual focus that would probably help me along

and
*) From what I can gather, the chances are that I'm likely to be using MF (macro) or AF (portraits), but rarely both in the same shot. So the quick shift may not be a big deal

EDIT: I haven't made a decision yet to be honest, I just voted in the poll so I can see the results. So take one off whatever score the Tammy has (had to vote for one of them!)

ANOTHER EDIT: Just saw the bokeh of the Pentax in this thread and am back at square one. My isn't this photography game wonderful?

Not total darkness, but in a dimly-lit room aiming at a small subject close to the minimum focusing distance. The subject had reasonable contrast but I think the latter factor was its primary problem. I wasn't so much criticising the 50-200, some of the images it produces are fabulous, more as an example of the potential usefulness of quick-shift focus as a means of counteracting the AF hunting which all macro lenses seem to suffer from to some extent.

EDIT: I remember some magazine had a group test of the Pentax, Tamron (+Canikon etc.) macro lenses a year or two ago, and still sells it online. Could anyone oblige me with the name of the mag?

The problem is that I live in Glasgow, which has a sum total of sod all Pentax dealers

That's a good point - maybe now might be the time to work out how to turn on Live View

I suppose that with the DOF being so shallow at 1:1, it might be more straightforward to use MF accurately than (for example) when taking a landscape shot with my kit lens. Quick Shift is something I had forgotten about - I actually use it on my kit telezoom (for example if the focus can't get started in low light, I shunt it to roughly the right place and then the AF can work).

Since I got my K20D I've found myself taking lots of photographs of plants and such - but limited by the maximum magnification of the kit lenses (I have the standard and tele zooms). To that end I'm hoping to make a macro lens my next purchase.

Up until recently my intention had always been to buy the Tamron 90mm f2.8, given its reputation for fantastic sharpness (plus the high price of the Pentax and Sigma in comparison). However I've since discovered a (reputable) dealer which is still selling new copies of the Samsung version of the DFA 100mm f2.8 (exact same lens AFAIK) for much the same price as the Tamron. This has royally screwed my pre-purchase research!

As I see it, the sharpness and colour rendition are a toss-up between the two. The main difference I see is in autofocus: my eyesight isn't fabulous, so I'm likely to be using autofocus more than the average macro user might.

Tamron: Has a focus limiter switch, which the Pentax doesn't. However I've also read that the Tamron has a tendency to hunt more than the Pentax.

Pentax: No focus limiter switch, but better general AF?

Basically, my find of the Samsung version of the DFA has put me back into a world of confusion: if anyone could offer suggestions by which I might dig myself out of it I would be hugely grateful!

Also bear in mind the price differential - the £400 you save by buying the DA could be go quite a long way towards another lens (80% of a 70mm limited for example)

Say that you spent 10 minutes doing promo photos for a bank and the lens was your share of the government bailout bonus

About a week and a half ago I ordered a 35mm f2 from Park Cameras. It turned out to be a duff copy (front focusing like mad), but they issued a full refund including paying for return postage. Can't say any fairer than that!

The excessive terms of the Treaty of Versailles didn't help either. Germany is STILL paying WWI reparations.

I'll second that. I handed my K20D (cunningly set to Aperture Priority over to my folks for them to take graduation pictures (of me, natch) neglecting to remember that I'd been taking indoor shots on 1600 the previous night. Suppose it's a tribute to the brilliance of the K20D that the prints still came out great!

It was sarcasm. Curse of the internet strikes again. Maybe Digg users are on to something with their '' pseudomarkup in posts

Only the DA* lenses are weathersealed (with the exception of the new WR kit lenses). So the 16-50 is weathersealed, but the 16-45 is not.