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12-12-2010, 03:59 AM   #16
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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.

12-12-2010, 04:04 AM   #17
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Thank you JT and everyone else who has commented - that is exactly the sort of information I'm looking for and it's really helping me to move towards a decision.

It seems I can't go wrong no matter which lense I pick - although I would like some more feedback on the Sigma but I understand it is a relatively new lense so far fewer people will have used / bought it.
12-12-2010, 04:14 AM   #18
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I have not faced any focus issue with my 17-50mm, pretty competent in my opinion. Pentax 16-50 might be slightly better but at the risk of prominent SDM failure rate, I wouldn't touch for the reason alone.

Between Sigma and Tamron, Tamron certainly outclasses Sigma, especially at wide open. Here is one with Tamron 17-50


Last edited by yusuf; 12-12-2010 at 05:07 AM.
12-12-2010, 04:27 AM   #19
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QuoteOriginally posted by Class A Quote
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.

That's a brilliant test for side to side comparisons ! I can't understand the text but from the shots this is what I got (although this could just be sample variation too) :

Sharpest at 16/17/18mm @ F2.8 : 1. Sigma 2. Tamron 3. Pentax
Warmest Colours at 16/17/18mm : 1. Pentax 2. Sigma 3. Tamron

Sharpest at 16/17/18mm @ F8 : 1. Sigma 2. Tamron 3. Pentax (noticeably darker too).
Warmest Colours at 16/17/18mm : 1. Sigma 2. Pentax 3. Tamron

Sharpest at 30mm @ F2.8 : 1. Sigma 2. Pentax 3. Tamron
Warmest Colours at 30mm : 1. Sigma 2. Tamron 3. Pentax

Sharpest at 30mm @ F8 : 1. Sigma 2. Tamron 3. Pentax
Warmest Colours at 30mm : 1. Pentax 2. Sigma 3. Tamron

By 50mm Pentax & Tamron seem to have taken over as #1 in the sharpness and colour warmth.

In PF Tamron is a clear winner, followed by Sigma and then Pentax.

Ghosting & flare : 1. Sigma 2. Tamron 3. Pentax

Bokeh : the Sigma seems smoother and isolates better (@2.8) with nothing much between the Pentax & Tamron.

Of course this is just one test I we can't vouch for the conditions / accuracy but it's interesting to see real life side-by-side comparisons nevertheless. One thing is clear, these lenses are so closely matched in IQ that I couldn't go wrong with any of them.

Thanks for posting that Class A.

If anyone can comment on the test or disagrees with my observations - please come forward and say why, I'd love to hear other people's opinions.

12-12-2010, 04:37 AM   #20
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QuoteQuote:
frogfish: It seems I can't go wrong no matter which lense I pick - although I would like some more feedback on the Sigma but I understand it is a relatively new lense so far fewer people will have used / bought it.
The Sigma, except for wide open, has the best MTF figures--outstanding numbers! It also has a little more barrell distortion than the Tamron @ 17mm, but the Da has more distortion @ 16mm, by far, than either of the other 2. I think the Sigma looks great, but I invested in Pentax for the SR in-body--would hate to pay for the image stabilization costs twice, which is what I would do if I bought the Sigma.

On the other hand, if HSM is your thing, the Sigma looks great. If the Sigma was an option when I bought my Tammy, I would have leaned towards the Sigma.

QuoteQuote:
frogfish: Sharpest at 16/17/18mm @ F2.8 : 1. Sigma 2. Tamron 3. Pentax
This is only referring to center sharpness. Tamron borders and extreme borders much better than the Sigma wide open, but wide open is the Achille's heel of the Sigma if ou ask me.

Last edited by Jewelltrail; 12-12-2010 at 04:41 AM. Reason: Add
12-12-2010, 05:34 AM   #21
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QuoteOriginally posted by Jewelltrail Quote
...
The hood on the Tamron is just right if you ask me.
+1 With this reversed on the lens it still goes nicely enough into its slot in the bag (hood end first). As for the FF/BF, this could be about the body being at the extremes of its tolerances too; the whole BF/FF issue is a bit of a mystery, really, as the AF system should compensate for lens variations as it is supposed to adjust the focus mechanism until the sensors report that focus has been obtained.
12-12-2010, 05:43 AM   #22
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I really like the DA *16-50. It certainly does have its weaknesses. From 16-18mm you are better off stopping down to f4. Corners and borders improve considerably. The biggest problem with all of these lenses that comes through clearly in this thread is that there is quite a bit of sample variation. Whichever lens you decide to get, you will need to shoot with considerably to be certain that it is not deficient in one of the areas mentioned. Many people have gone through two or three copies of the Tamron to get a good one, many people have gone through the same number of copies of the Pentax to get a good one; however, when they are good, they are really good.

Unfortunately, there are a lot of bad copies out there that sour people on a particular lens.
12-12-2010, 06:08 AM   #23
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QuoteQuote:
jolepp: As for the FF/BF, this could be about the body being at the extremes of its tolerances too; the whole BF/FF issue is a bit of a mystery, really, as the AF system should compensate for lens variations as it is supposed to adjust the focus mechanism until the sensors report that focus has been obtained.
Agreed--I recently bought a Tamron 28-75mm, which worked perfectly for the seller on her K7 and worked pefectly on the person's camera from whom she purchased the lens. However, on my K20d, it is a disaster. with FF so bad I had to shoot 4gb @ a family reunion just to get a couple of handfuls of decent shots. This means at least some bf/ff issues are body related--no doubt.

12-12-2010, 01:09 PM   #24
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QuoteOriginally posted by Frogfish Quote

Thanks for posting that Class A.

If anyone can comment on the test or disagrees with my observations - please come forward and say why, I'd love to hear other people's opinions.
I saw this test but didn't bother to comment at the time.
Now that you've summarised it succinctly here, I'll say that I don't care what the test says or how they got their results, my own experience with the Pentax DA* 16-50 has been nothing less than amazing in *every* category mentioned - even the supposed frazzled bokeh it exhibits.

I've used both the Sigma and Tamron and whilst I found them very capable lenses producing very decent results, I always found myself liking the results I got from the DA* (more for the microcontrast and 3D rendering than anything else) - that's *my* opinion, but of course because n=1 for this opinion, it doesn't mean much (except to me ).

But real-world results here can give a taste of the Pentax's virtues:
https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/106084-da%2A-1...at-can-do.html
12-12-2010, 03:23 PM   #25
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QuoteOriginally posted by jolepp Quote
...the whole BF/FF issue is a bit of a mystery, really, as the AF system should compensate for lens variations as it is supposed to adjust the focus mechanism until the sensors report that focus has been obtained.
The issue is that the AF system doesn't "see" the same as you do. It uses f/5.6 as an effective aperture and any spherical aberration or perhaps even decentering can cause it to chose a focus setting that doesn't make sense for the final image at a different shooting aperture.

QuoteOriginally posted by Ash Quote
I've used both the Sigma and Tamron and whilst I found them very capable lenses producing very decent results, I always found myself liking the results I got from the DA* (more for the microcontrast and 3D rendering than anything else)...
Do you still happen to have images from all three lenses that might be useful for a comparison? It is probably too much to ask for since unless the images are rather similar, subject matter, shooting conditions and the photographer will have a much larger influence on the appeal of an image than subtle lens differences.

It might be the case that the comparison I linked to used a suboptimal copy of the Pentax 16-50 but there are no obvious signs for that.

The Pentax 16-50 thread you linked to has some nice images but it isn't clear to me which of these would not have been possible with any of the other two lenses.
12-12-2010, 04:19 PM   #26
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I have the DA* 16-50/2.8 and love the renditions so much that I will keep it as a manual lens if the SDM ever goes out. At these focal lengths zone focusing works fine anyway. When using this lens or the DA 12-24 I set my program mode to MTF in critical focusing shooting (low light mostly) and Depth of field preference for outdoors.
12-12-2010, 04:28 PM   #27
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QuoteOriginally posted by Frogfish Quote
That's a brilliant test for side to side comparisons ! I can't understand the text but from the shots this is what I got (although this could just be sample variation too) :

Sharpest at 16/17/18mm @ F2.8 : 1. Sigma 2. Tamron 3. Pentax
Warmest Colours at 16/17/18mm : 1. Pentax 2. Sigma 3. Tamron

Sharpest at 16/17/18mm @ F8 : 1. Sigma 2. Tamron 3. Pentax (noticeably darker too).
Warmest Colours at 16/17/18mm : 1. Sigma 2. Pentax 3. Tamron

Sharpest at 30mm @ F2.8 : 1. Sigma 2. Pentax 3. Tamron
Warmest Colours at 30mm : 1. Sigma 2. Tamron 3. Pentax

Sharpest at 30mm @ F8 : 1. Sigma 2. Tamron 3. Pentax
Warmest Colours at 30mm : 1. Pentax 2. Sigma 3. Tamron

By 50mm Pentax & Tamron seem to have taken over as #1 in the sharpness and colour warmth.

In PF Tamron is a clear winner, followed by Sigma and then Pentax.

Ghosting & flare : 1. Sigma 2. Tamron 3. Pentax

Bokeh : the Sigma seems smoother and isolates better (@2.8) with nothing much between the Pentax & Tamron.

Of course this is just one test I we can't vouch for the conditions / accuracy but it's interesting to see real life side-by-side comparisons nevertheless. One thing is clear, these lenses are so closely matched in IQ that I couldn't go wrong with any of them.

Thanks for posting that Class A.

If anyone can comment on the test or disagrees with my observations - please come forward and say why, I'd love to hear other people's opinions.
From what I could tell from those comparisons, I agree. Though I have seen a number of other that claim the Tamron is sharper than either, especially in the corners, though they might have been with the older 67mm filter vs newer (better?) 72mm filter version.

I have the 72mm sigma and love it, used it for SiN. The closer focusing capability, less focus field curvature, and talk of better bokeh (still pales in comparison to primes...) is ultimately what sold me over the Tamron.

Last edited by Eruditass; 12-12-2010 at 04:36 PM.
12-12-2010, 05:30 PM   #28
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Class A unfortunately I have never owned the Sigma and Tamron and so don't have images of my own to present here from these lenses. So my opinion is not only subjective but it's based on limited 'testing' of others' lenses.

Indeed, you can't tell from any resized image how the lens compares with another, so that comparison test may be the closest thing to objective results. Though I may have images from the 16-50 that appear sharper at 100%.
12-13-2010, 04:41 AM   #29
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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) !
12-13-2010, 10:15 AM   #30
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QuoteQuote:
frogfish: 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.
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!
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