I got one of the cheap plastic Vivitar 100mm macro lenses from eBay a while ago. Now I'm thinking about upgrading to a Pentax one.

The version which preceded the current WR model, though technically discontinued, is still available 'new' from various sources at a considerably lower price than the WR.

My question is, besides the obvious lack of weather sealing, is there any other significant disadvantage to the non-WR model as opposed to the WR? I'm trying to decide whether I should go for the non-WR version now or save up my pennies a bit longer for the WR.

Any suggestions appreciated!

I can't say my Tamron 17-50 has been entirely without issues, but sharpness sure ain't one of them. The sharpness really shouldn't be an issue. Most of the reviews on the internet concur that this is one of the sharpest zooms around, and absolutely stellar for its price point.

If you think it's problematic send it back to Tamron to take a look at it (assuming it's still under warranty).

OTOH the K-30 is supposed to have better AF than the K-5. Now this might not seem like a bid deal to you but it is, potentially, to me. I do a LOT of low light, hand-held people photography (i.e not the kind of low light photography where you can take your time, use long exposures and so forth) and the hit-and-miss nature of the K-5's AF in these conditions is genuinely the ONE thing about the camera that frustrates me.

Of course whether the K-30 would be worth it for me depends a great deal on just how much the AF system has been improved in respect to the above conditions. This remains to be seen so I'll be waiting for full reviews and more specifically the results of any testing on the AF system.

I do agree with you about the ISO button though. I'd also miss the AF mode switch on the rear of the camera and I can live without the top LCD but it would take a little getting used to.

As I'd be looking at the K-30 as a second body the loss of the other features you mentioned wouldn't be an issue - I'd still have the K-5 if I needed them.

In all honesty, from my perspective I still think that 12-bit RAW (as opposed to 14) is the K-30's biggest disadvantage in comparison to the K-5.

I think the K-5 is just a little bit more expensive at the moment. 14-bit RAW is worth the extra cash, IMO. On the other hand, when the K-30 comes down in price it might be a different matter. I doubt the K-5 will come down any further.

Tempting as a second body to my K-5 once it comes down a bit from the lauch price. I'm not realistically going to be able to afford the new flagship.

Well to be completely truthful, the lens release button could do with some improvement. On my K-5 at least, it feels 'wobbly' to the touch. In light of the fact that there have been a few reports of it falling off, this particular trait does not inspire confidence.

On the other hand, this one flaw aside, there is nothing else about the K-5 which could possibly be described as 'flimsy'.

Specifically, it was compared to the D300s. Let's see what DxOMark thinks...

Comparison.

I'm not about to do the 'defensive fanboy' thing, but if I were Pentax, I'd be having a word with my lawyers. Whilst reviews are largely subjective, I don't think it would be difficult to present enough evidence to a court to demonstrate that describing the K-5's high ISO performance as 'sub-par' amounts to an outright falsehood. Until now I haven't heard even the K-5's worst detractors try to claim that its high ISO performance is anything less than outstanding.

Sorry, not sure what went wrong with that link.

I don't imagine there's that much demand for a square sensor but I think it would be great. The main advantage (for me) being the ability to have a button to flip between landscape and portrait modes without having to rotate the camera. I have had a go at using a grip but it doesn't make it any less awkward in my opinion. (Almost) all the controls just become less accessible.