[yusuf]

The Tamron 17-50 is very sharp, evne to the corners, from wide open & stays that way stopping down--impressive if you ask me. And it does focus quickly. The build quality is nice, better than my Tammy 28-75.

Tamron warranty in the States in 6 year!

Agree about sharpness, though I would rank build quality of both Tammy the same.

[gnaztee]

I was surprised by this Pentax, Tamron, Sigma comparison. According to this test, the Pentax would the least preferable option.

It is a shame that many have FF issues with their first Tamron copies, but note that the Pentax 16-50 also had a bad history regarding decentering. Not sure to what extent this has been ironed out.

A lot of people responding to this lens comparison link, but I don't think anybody has mentioned this. Just to be clear, the Sigma looked at here is the 18-50mm, not the new 17-50mm that the OP asked about.

[Pentaxor]

Today I went and compared the Tamron to the 16-50 on my K7 at my favourite Pentax stockist (the Sigma wasn't in stock - should be there within the week). I was shocked - the sharpness from the Tamron blew the Pentax away at 2.8 although at F8 there was nothing in it. I also found the Tamron very fast to focus - I'd expected Pentax to edge it but there was nothing in it. I can't say that build quality looked an issue on the Tamron either - by look & feel there was nothing in it - but I did miss the quick-shift.

US$900 and a one year guarantee vs. US$360 and a three year guarantee ..... it's down to the Tamron or the Sigma (quoted US$550) I'm afraid, though I will be sorry to give up the WR but if the Tamron/Sigma takes a drenching I can buy another one (and get another new 3 year guarantee) !

do you have the NON-VC Tamron or the VC type? the 2nd one was reported to be not as good as the Non-VC type.

[Pentaxor]

A lot of people responding to this lens comparison link, but I don't think anybody has mentioned this. Just to be clear, the Sigma looked at here is the 18-50mm, not the new 17-50mm that the OP asked about.

also, it seems that the Sigma 17-50 is a great lens as well like the Tamron. I think this would come down to budget and HSM. although I have a feeling that the Sigma may slightly be better.

[Jewelltrail]

Pentaxor: do you have the NON-VC Tamron or the VC type? the 2nd one was reported to be not as good as the Non-VC type.

Pentaxor, he has the non-VC--see his price quote of $360--this is the give away.

[Jewelltrail]

Pentaxor: also, it seems that the Sigma 17-50 is a great lens as well like the Tamron. I think this would come down to budget and HSM. although I have a feeling that the Sigma may slightly be better.

The new Sigma we are discussing is image stablized, which greatly increases the price. I do not want to pay for IS again--it is iin the price of my K20d ($1200 new). I agree, the Sigma, newest model, is better.

Note:

All my comments in this thread are for the 17-50 Sigma--HSM--OS lens. That is the lens I assume Mr Froggy means when he refers to the 17-50 Sigma in his OP.

[Frogfish]

do you have the NON-VC Tamron or the VC type? the 2nd one was reported to be not as good as the Non-VC type.

I haven't bought either yet .... I was trying out the non-VC version (as someone here correctly pointed out - the VC version is not made in a Pentax mount).

[Frogfish]

The new Sigma we are discussing is image stablized, which greatly increases the price. I do not want to pay for IS again--it is iin the price of my K20d ($1200 new). I agree, the Sigma, newest model, is better.

Note:

All my comments in this thread are for the 17-50 Sigma--HSM--OS lens. That is the lens I assume Mr Froggy means when he refers to the 17-50 Sigma in his OP.

Yes, correct. I have read that when using the Sigma (HSM version) that the in-body SR should be switched off as Sigma's OS works better - this, allied with the better sharpness, bokeh, CA handling etc. (over the Pentax and mostly - except CA - over the Tamron too), means I may well see the value of paying more for this lense (over the Tamron). However I'm not sure my LBA will let me wait long enough to confirm this !

[Pentaxor]

Yes, correct. I have read that when using the Sigma (HSM version) that the in-body SR should be switched off as Sigma's OS works better - this, allied with the better sharpness, bokeh, CA handling etc. (over the Pentax and mostly - except CA - over the Tamron too), means I may well see the value of paying more for this lense (over the Tamron). However I'm not sure my LBA will let me wait long enough to confirm this !

I'm not sure what you meant by the Tamron VC version not available for K-mount, but from the lens that are being posted for sale at certain shops, they have VC even for the Pentax mount. are you referring to the one that is being sold to you? I'm a bit wary about this since I'm a bit considering the non-VC lens as well.

the IQ between the two lenses are somehow a mix. both are great. one is slightly better in overall sharpness and has great CA control, while the other one has a strong center resolution and better bokeh. I would think that the OS and HSM are the things to consider for the Sigma's pricepoint. both lenses are separated by $200. so if those two are worth the additional cost, then it's a fine choice. question is, can you afford an additional $200?

[Jewelltrail]

Frogfish: Yes, correct. I have read that when using the Sigma (HSM version) that the in-body SR should be switched off as Sigma's OS works better.

I understand in-lens IS is usually better than in-body, but that is more true of the longer focal lengths. Pentax IS excels at shorter focal lengths. How much better can the Sigma be? It is not like the 17-50mm range is in dire need of iS to begin with. If the HSM is important, be sure to fend off your LBA--else you'll have regrets. Besides, I'm dying to see shots posted with this Sigma.

[Frogfish]

I'm not sure what you meant by the Tamron VC version not available for K-mount, but from the lens that are being posted for sale at certain shops, they have VC even for the Pentax mount. are you referring to the one that is being sold to you? I'm a bit wary about this since I'm a bit considering the non-VC lens as well.

the IQ between the two lenses are somehow a mix. both are great. one is slightly better in overall sharpness and has great CA control, while the other one has a strong center resolution and better bokeh. I would think that the OS and HSM are the things to consider for the Sigma's pricepoint. both lenses are separated by $200. so if those two are worth the additional cost, then it's a fine choice. question is, can you afford an additional $200?

Actually the VC version is only available in Canon / Nikon mounts, I'm guessing because we already have SR

Tamron -High-Speed Zoom Lenses (Di II Lenses)

The money isn't the issue it's 'value for money' ! Hence why I've dropped the 16-50 from consideration. It's between those two now, preference may be for the Sigma but I haven't tried it out yet - whereas the Tamron was stunning in it's sharpness and I nearly bought it on the spot !

[Frogfish]

I understand in-lens IS is usually better than in-body, but that is more true of the longer focal lengths. Pentax IS excels at shorter focal lengths. How much better can the Sigma be? It is not like the 17-50mm range is in dire need of iS to begin with. If the HSM is important, be sure to fend off your LBA--else you'll have regrets. Besides, I'm dying to see shots posted with this Sigma.

I'm giving it a week (maybe) if the Sigma isn't in then I'm going back for the Tamron (should have marked the box so I know which copy it was )

My reasoning goes like this : I need it (*rolls eyes*) for the Xmas season and since the Tamron isn't that expensive I could try it out for a few months and if I then get my hands on a Sigma, and prefer it, I could sell the Tamron on at very little loss (still 2.5 yrs guarantee here) ... maybe the Sigma would also have come down in price a little by then too.

[Pentaxor]

Actually the VC version is only available in Canon / Nikon mounts, I'm guessing because we already have SR

Tamron -High-Speed Zoom Lenses (Di II Lenses)

The money isn't the issue it's 'value for money' ! Hence why I've dropped the 16-50 from consideration. It's between those two now, preference may be for the Sigma but I haven't tried it out yet - whereas the Tamron was stunning in it's sharpness and I nearly bought it on the spot !

well that's nice then. since I'm trying to avoid the VC version which was reported to be a disappointment.

[kari]

I had to make this decision a while back and what eventually won me over on the DA* was actual photos taken with it compared to the Sigma and Tamron. It just had that extra something in the colours and contrast that gave it the 'wow' factor. You can look at test charts all day, but they do not really give the full picture.

[Pentaxor]

I had to make this decision a while back and what eventually won me over on the DA* was actual photos taken with it compared to the Sigma and Tamron. It just had that extra something in the colours and contrast that gave it the 'wow' factor. You can look at test charts all day, but they do not really give the full picture.

there should be something to give. although you are correct with regards to color. that's the thing that makes the Pentax lens.