Macro lens shootout - binary choice

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!

Don't forget quick shift focus as a plus point.

K.

I have the Pentax lens. I have no experience of the Tamron, but don't miss the focus limiter. I can't say I've experienced the min-to-max focus range hunting that a limiter is supposed to prevent.

I let the lens do it's thing in AF then fine-tune focus manually.

They are both fine and you can make a wrong choice really.
AF and macro don't go well together, most of the time I put the lens near the focus I want and use my body to get the focus right, there is really no simple way of doing it I'm afraid.

The DFA has quick-shift and I like that and the lens is light.

The focus limiter on the Tamron makes it better for general use but like said AF is no real option with macro.

Most of the time Pentax is a better buy simply because of the resell value but since it's a Samsung badge things are a bit different.

Just try them out and get the one that feels best, that's the only real advice I can give you about the purchase.

Live View might help you more than AF for macro.

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).

That's right, and the larger aperture of a macro or prime lens has a lot to do with it as well. And you usually have more time and relaxation when doing macro, especially when using a tripod.

The main problem when using AF for macro, or still life, is that where you want to focus often doesn't coincide with an AF point. That's awkward when the camera is on a tripod and you don't want to, or can't, move the subject.

Glasgow has a Pentax Pro Dealer in the shape of Merchant City Cameras although I do find them too expensive. My recent K20D came from SRS at £100 less. Calumet are also Pentax dealers but the Glasgow store doesn't stock Pentax. Whether or not they would get something in for you I don't know.

I also think that AF is inappropriate with macro and Liveview is the way forward here.

Are you trying to focus your 50-200 in total darkness? Mine focuses accurately and reasonably quickly at EV 0.4 at 100ISO which is pretty dark and equates to a 15 second exposure at maximum aperture. Remember that the camera can't focus on subjects with extremely low contrast such as plain wall, in really low light conditions it needs a pattern or texture to lock on to.

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?

I'd be wary of reading too much into a magazine review.

Image quality's going to be great from either one. I think I'd go for the Samsung if the price is the same.

Dan

I have a Tamron Adaptall 2 90mm MF macro and the Pentax DF-A 100mm.
The Tamron (IMO) is better built and sharper but the Pentax gives a more pleasing image colour wise. Don't use AF on the Pentax btw, have always found manual best for macro.

I have long been wanting a Sigma 70mm f2.8 macro as I have heard this is a excellent lens and managed to grab one for a decent price on Ebay at the weekend which arrived today. Bit short for bugs but am looking forward to trying it out.

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?

From what I've seen the Tamron is only marginal sharper over the whole range but Pentax has the highest peek and has nicer colours... we can probably going like that forever since there is little in between them but they will handle differently.

MF is so good as the same for both, besides that one has quickshift and the other has an easy switch system in the focus ring.

Ken said Merchant City Cameras is in Glasgow, just try them both out if they have them. You can also try the Tamron on a Nikon mount it's the same lens and pick the one that feels and handles the best for you.
If they don't have the Pentax the Tokina is very much like that one, it would at least give you a good idea how it would be.

David I'm not making it easy for you
The Tamron is so good as the same though with the Bokeh.

Am I right in saying though, that to switch from AF to MF on the Tamron I would have to operate BOTH the focus ring clutch on the lens, AND the body AF-> MF switch? Whereas on the Pentax I assume it would work the same as my other lenses ie body switch set to MF = lens is MF?