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12-15-2010, 09:29 PM   #61
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I see as many "heavily" PPed images with Pentax lenses as I do with other brands. Also, all pics are PPed, whether to the camera's processing engine specs, or to the tastes of the lens owner. Obviously, Pentax engineers their camera bodies for optimum results with Pentax lenses--Da!!! It is not in Pentax' best interest to ensure 3rd party lenses reach optimum results on their bodies.

That said, the Tamron lenses I use all produce wonderful images, even when simply taken from RAW, directly to a jpg. A great image is a great image. However, shooters differ on opinion with respect to the various elements which make an image--which is what birthed the RAW invention in the first place.

I looked, but do not see any "magic pixie dust" on the Tamron lens, but these things I can see and measure from the Tamron:

Better wide open than Da
Better Ca control than Da
Better sharpness than Da
Noticecably lighter than Da
Better warranty than DA, by a whole lot!
Faster focus than Da
More reliable focus mechanism than Da (when you get a good one)
Smaller filters than Da
Nicer hood than Da
Better barrell distortions at wide end than Da
Better flare control than Da

The OP can gather our discussion, process it into his decision equation, and make his own choice. If Pentax met all buyers' expectations, there would be no Sigma, no Tamron. Also, all 3 of these lens makers make each other's products better: Fair competition is healthy, and the consumer reaps its harvest.

12-15-2010, 10:27 PM   #62
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QuoteOriginally posted by Jewelltrail Quote
I see as many "heavily" PPed images with Pentax lenses as I do with other brands. Also, all pics are PPed, whether to the camera's processing engine specs, or to the tastes of the lens owner. Obviously, Pentax engineers their camera bodies for optimum results with Pentax lenses--Da!!! It is not in Pentax' best interest to ensure 3rd party lenses reach optimum results on their bodies.

That said, the Tamron lenses I use all produce wonderful images, even when simply taken from RAW, directly to a jpg. A great image is a great image. However, shooters differ on opinion with respect to the various elements which make an image--which is what birthed the RAW invention in the first place.

I looked, but do not see any "magic pixie dust" on the Tamron lens, but these things I can see and measure from the Tamron:

Better wide open than Da
Better Ca control than Da
Better sharpness than Da
Noticecably lighter than Da
Better warranty than DA, by a whole lot!
Faster focus than Da
More reliable focus mechanism than Da (when you get a good one)
Smaller filters than Da
Nicer hood than Da
Better barrell distortions at wide end than Da
Better flare control than Da

The OP can gather our discussion, process it into his decision equation, and make his own choice. If Pentax met all buyers' expectations, there would be no Sigma, no Tamron. Also, all 3 of these lens makers make each other's products better: Fair competition is healthy, and the consumer reaps its harvest.
for what it's worth, Pentax is also partly responsible for Tamron's and Sigma's success. if not for the outrageous price, SDM unreliability + limited warranty, Pentax could had gained a better market share.

I'm still 100% unsure that I would invest on a DA* zoom lens particularly the faster zooms.
12-15-2010, 10:57 PM   #63
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QuoteOriginally posted by Jewelltrail Quote
I looked, but do not see any "magic pixie dust" on the Tamron lens, but these things I can see and measure from the Tamron:.
I'm not sure these are objectively shown, but IMO:

Better wide open than Da - not in my experience. f/2.8 at 35-50mm, where I used it the most, was simply remarkable on the DA*

Better Ca control than Da - didn't get the chance to test this, but I've had no CA corrections needed on any of my shots with the DA* - so this is of limited advantage to me

Better sharpness than Da - perhaps at 17mm up to f/5.6, but otherwise comparable from my point of view

Noticecably lighter than Da - not a significant advantage to me

Better warranty than DA, by a whole lot! - if warranty matters, as it certainly does with SDM, then it would be prudent to take out longer term warranty

Faster focus than Da - possibly, but not greatly so

More reliable focus mechanism than Da (when you get a good one) - no comment

Smaller filters than Da - why should this matter?

Nicer hood than Da - subjective. I like the DA* hood very much more

Better barrell distortions at wide end than Da - the wide end is the DA*'s weakness in most aspects, though this one can be reasonably corrected

Better flare control than Da - I've compared the two in this regard and find the flare in the DA* actually quite appealing, despite being more obvious

I suppose we may like what we have or what we're used to, but I don't find these aspects convincingly proven, and most going quite the other way (and I'm not talking about MTF data).
12-15-2010, 11:42 PM   #64
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QuoteQuote:
Pentaxor: for what it's worth, Pentax is also partly responsible for Tamron's and Sigma's success. if not for the outrageous price, SDM unreliability + limited warranty, Pentax could had gained a better market share.
Yes, I agree--that is partly what I meant when I wrote this:

QuoteQuote:
jewelltrail: If Pentax met all buyers' expectations, there would be no Sigma, no Tamron. Also, all 3 of these lens makers make each other's products better: Fair competition is healthy, and the consumer reaps its harvest.
QuoteQuote:
Pentaxor: I'm still 100% unsure that I would invest on a DA* zoom lens particularly the faster zooms.
Again agreed. I have seen some awesome shots done with them, but the life expectancy for the SDM, coupled with the Warranty, keeps me %100 entenched in 3rd party camps. That said, a lot of my awesome glass is Pentax, just no $$ to be spent on these Da* Zooms by me!

12-16-2010, 12:29 AM   #65
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The Tamron and the Sigma have two big disadvantages: They have no "Pentax" label and have no "*" designation. In particular the "*" aura of something special -- helped by a non-budget price -- seems to do a lot for the Pentax 16-50, oops forgot the "*" didn't I?

The claims for better colour and or micro contrast are not backed up with supporting images so I don't consider them to be helpful at all. The comparison images of the test I linked to earlier speak a clear language to me. Not in one category did the Pentax 16-50 convince with IQ superiority or magical rendering.

There are a number of lenses that make it worthwhile choosing the K-mount but the Pentax 16-50 isn't one of them AFAIC. Convincing me otherwise requires valid image comparisons as opposed to repeated claims that may seem plausible given the brand, price and the "*" designation of the lens but have not been demonstrated.

Last edited by Class A; 12-16-2010 at 02:46 AM.
12-16-2010, 01:09 AM   #66
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QuoteOriginally posted by Ash Quote
I'm not sure these are objectively shown, but IMO:

Better wide open than Da - not in my experience. f/2.8 at 35-50mm, where I used it the most, was simply remarkable on the DA* I have only tested the two lenses for an hour or so but the Tamron was certainly better under those limited conditions.

Better Ca control than Da - didn't get the chance to test this, but I've had no CA corrections needed on any of my shots with the DA* - so this is of limited advantage to me. But is a measurable fact.

Better sharpness than Da - perhaps at 17mm up to f/5.6, but otherwise comparable from my point of view. I'd agree with this but also at 50mm up to F8 (from my limited testing).

Noticecably lighter than Da - not a significant advantage to me. But will be to some people - especially when packing up a bag for an outing.

Better warranty than DA, by a whole lot! - if warranty matters, as it certainly does with SDM, then it would be prudent to take out longer term warranty. Which means adding another ($100 ?) to the cost of an already expensive lense. And the question remains - why do Pentax not stand behind their lenses ? See below for Warranty questions.

Faster focus than Da - possibly, but not greatly so. Fairly even from my testing under limited conditions.

More reliable focus mechanism than Da (when you get a good one) - no comment

Smaller filters than Da - why should this matter? Cost. Sometimes quite appreciable.

Nicer hood than Da - subjective. I like the DA* hood very much more. Subjective.

Better barrell distortions at wide end than Da - the wide end is the DA*'s weakness in most aspects, though this one can be reasonably corrected. The same argument you use for colour & microcontrast - why should you have to correct it ? And I would suggest barrel distortions are more difficult to correct and impact the shot (losing the edges) more than subjective colour / microcontrast 'corrections'

Better flare control than Da - I've compared the two in this regard and find the flare in the DA* actually quite appealing, despite being more obvious. Appeal is subjective but the better flare control fo the Tamron is proven.

I suppose we may like what we have or what we're used to, but I don't find these aspects convincingly proven, and most going quite the other way (and I'm not talking about MTF data).
Jasvox made a good point above - we all want our lenses quality to be validated, thereby endorsing our decision to buy them, plus of course as Pentaxians we also want Pentax lenses to be recognised as the very highest quality some of them undoubtedly are (Ltd's, 50-135 / 60-250 and some FAs) - the 43 Ltd being my favourite lense bar none.

It is also wrong of course to deceive ourselves that MTF figures have no relevance on the quality of the images our lenses / cameras are capable of producing. They certainly do.

The PP question is another issue entirely (thanks for pointing out that very interesting thread I'll be commenting in there) but suffice to say that if we are not professional photographers then we do this for the sake of art and as in any artistic field the tools you use are just that, a means to an end - helping us to produce the best art we are capable of.

Warranties.
This is a highly debatable subject but the fact is that Pentax has one of the lowest failure rates amongst any lense manufacturers (inc. SDM issues) so why do they not stand behind this reputation with a proper guarantee ?

I can't do this for every country and as I live in China the guarantees here are shorter than most other countries however a quick scour of the web elicits this :

Sigma - In Canada a 10 year guarantee on EX lenses
Pentax - One year. Why ?!
Canon - One year (though I've heard fantastic things about them fixing numerous lenses out of warranty, for free, in the USA at least).
Nikon - 4 years
Tamron - 3 to 7 years depending on where you live.

Last edited by Frogfish; 12-16-2010 at 01:26 AM.
12-16-2010, 01:29 AM   #67
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Looks like you've made up your mind on it Frogfish.
No point in continuing on with this argument.
DA* is unrivalled - can't back it up with facts, but it's shown in many threads here to be the most desirable in terms of results.
No doubt the wide end issues aren't insignificant, but that's why I have a DA 12-24.
YMMV.
12-16-2010, 01:46 AM   #68
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QuoteOriginally posted by Frogfish Quote

Warranties.
This is a highly debatable subject but the fact is that Pentax has one of the lowest failure rates amongst any lense manufacturers (inc. SDM issues) so why do they not stand behind this reputation with a proper guarantee ?

here is my feeling regarding the issue why Pentax hasn't considered or felt necessary to have a longer warranty. since Pentax lenses had been that sturdy enough to withstand physical forces for a number of years, they might had felt a longer warranty is unnecessary. this however holds true until the SDM failure reports start piling in. the SDM failure is a tricky one since it is not like the usual lens B/F focusing that immediately occurs or detectable but rather starts to show most likely after the lens' warranty period expire.

my guess is that Pentax never expected these problems to occur or haven't really tested their SDM technology thoroughly and longer. they might had tested the lens for 6 months and considered them to be reliable enough, not aware of the impending failure in a few more months.

unlike B/F focusing problems which can be resolved by securing a good copy or serviced perfectly and have a long lasting lens, SDM failure can be a recurring problem due to wear and tear.

for such a costly high-end lens, it does indeed fail to meet customer satisfaction at a highend level.

I just hope the DC motor does not run into the same problem as the SDM and could become the replacement for the SDM. let's see after lens warranty expires after a year.

12-16-2010, 01:46 AM   #69
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QuoteOriginally posted by Ash Quote
Looks like you've made up your mind on it Frogfish.
No point in continuing on with this argument.
DA* is unrivalled - can't back it up with facts, but it's shown in many threads here to be the most desirable in terms of results.
No doubt the wide end issues aren't insignificant, but that's why I have a DA 12-24.
YMMV.
Pretty much

I still haven't got my hands on the new 17-50 Sigma 2.8 yet but if I can't by the weekend then I'll buy the Tamron for now and try out the Sigma later, an easy and low cost upgrade if necessary.

I've had a lot of help coming to this decision from posters on three forums (here by far the most, and also the liveliest debate) and I have to say the debate has been enlightening and extremely helpful no matter on which side of the fence people sit. I've learnt a lot more about the Pentax & Tamron in particular - guess the Sigma is just too new to most people.

In the end the SDM issues - which seem, by far, to affect the 16-50 the most, the length of the guarantee - which goes hand in hand with the SDM issues, test figures from DXO, SLRgear etc. and image comparisons from numerous sources on the web, helped me come to a decision.

To date only four lenses have survived my continual striving to upgrade (also known as LBA) : 43 Ltd (my first lense), 10-20, CZJ Electric 135 and SMC Tak 300mm so who knows how long the Tamron / Sigma will last, but I think I'm happy with the conclusion I've arrived at. Nothing at all against Pentax lenses though ..... the 60-250 is on the horizon and closing fast !

Last edited by Frogfish; 12-16-2010 at 01:55 AM.
12-16-2010, 01:53 AM   #70
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QuoteOriginally posted by Pentaxor Quote
here is my feeling regarding the issue why Pentax hasn't considered or felt necessary to have a longer warranty. since Pentax lenses had been that sturdy enough to withstand physical forces for a number of years, they might had felt a longer warranty is unnecessary. this however holds true until the SDM failure reports start piling in. the SDM failure is a tricky one since it is not like the usual lens B/F focusing that immediately occurs or detectable but rather starts to show most likely after the lens' warranty period expire.

my guess is that Pentax never expected these problems to occur or haven't really tested their SDM technology thoroughly and longer. they might had tested the lens for 6 months and considered them to be reliable enough, not aware of the impending failure in a few more months.

unlike B/F focusing problems which can be resolved by securing a good copy or serviced perfectly and have a long lasting lens, SDM failure can be a recurring problem due to wear and tear.

for such a costly high-end lens, it does indeed fail to meet customer satisfaction at a highend level.

I just hope the DC motor does not run into the same problem as the SDM and could become the replacement for the SDM. let's see after lens warranty expires after a year.
That may be correct however many consumers are not aware of the historical longevity of Pentax lenses and when quoted a one year guarantee that can give nothing but a negative impression considering the high cost of top end lenses.

Eventually Pentax will have to come in line (as will Canon) as car manufacturers had to, due to consumer pressure. Over a generation going from one year to 10 years (Hyundai).

However for Pentax it would have been the perfect response to the SDM issue (without actually acknowledging it of course) to extend their guarantee to say 3 years rather than one.
12-16-2010, 02:00 AM   #71
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QuoteOriginally posted by Frogfish Quote

However for Pentax it would have been the perfect response to the SDM issue (without actually acknowledging it of course) to extend their guarantee to say 3 years rather than one.

extended warranty + resolving the issue for the better would be a better idea. certainly people wouldn't want to have their lenses serviced every year after every failure.
12-16-2010, 05:36 AM   #72
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Just a quick comment on warranties. I agree that giving a longer warranty, at least to SDM lenses would sell more lenses as there is a lot of fear and uncertainty about the subject. To this point, Pentax has never made an official statement about an "SDM problem" and probably never will. Still, as Pentaxor says, I would far rather have a lens with a one year warranty that never needs service, than a lens with a ten year warranty that needs service every eighteen months.
12-16-2010, 06:01 AM   #73
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QuoteOriginally posted by Rondec Quote
Just a quick comment on warranties. I agree that giving a longer warranty, at least to SDM lenses would sell more lenses as there is a lot of fear and uncertainty about the subject. To this point, Pentax has never made an official statement about an "SDM problem" and probably never will. Still, as Pentaxor says, I would far rather have a lens with a one year warranty that never needs service, than a lens with a ten year warranty that needs service every eighteen months.
Me too. Except such lenses don't exist.
12-16-2010, 07:57 AM   #74
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watching this thread with interest. Have a Sigma 17-70 but thinking of getting either the 17-50 or the 16-50.
12-16-2010, 09:52 AM   #75
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QuoteOriginally posted by Rondec Quote
Just a quick comment on warranties. I agree that giving a longer warranty, at least to SDM lenses would sell more lenses as there is a lot of fear and uncertainty about the subject. To this point, Pentax has never made an official statement about an "SDM problem" and probably never will. Still, as Pentaxor says, I would far rather have a lens with a one year warranty that never needs service, than a lens with a ten year warranty that needs service every eighteen months.
3 years of warranty would be ideal for me
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