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Tamron 17-50 2.8 or Sigma 18-50 2.8 EX Macro for Pentax
#1
Currently I am planning an update for my standard lens for my Pentax K-5. As the Pentax DA* 16-50 is too expensive for me at this point and because the reviews of this lens are not that positive, I am looking at alternatives. Due to my limited budget, I have come up with two alternatives:



1. Tamron 17-50 2.8 non-VC (old version) €314

Pro's: - 17 mm wide

- Corner resolution is pretty good, even at f2.8

- Very positive reviews here and elsewhere

Con's: - Build quality

- AF noise

- Quality control issues



2. Sigma 18-50 2.8 EX DC Macro €349

Pro's: - I expect better build quality than the Tamron

- AF is supposedly much more quiet than the Tamron

Con's: - 18 mm wide, but actually -according to some reviews- it is close to 19 mm in real life

- Resolution of the borders at large apertures is dissapointing, need to stop down to f5.6



I just have difficulty to choose between these lenses. My reason to buy this lens is low light photography and portraits and off course IQ. I have to say that I really appreciate good built quality and that I do not mind AF noise, but it is nice if the noise is not too disturbing. Another question I would like to ask is how I can test these lenses in the shops for decentering or other QC issues. I mean they do not have a brick wall inside and most of the shops here in the Netherlands are situated in industry parks where it is very hard to find a brick wall in the first place. I was planning on taking a newspaper with me to test if the focus accuracy is decent.



Thanks for all your help!
#2
[quote name='Lampo' timestamp='1300102110' post='6739']

Currently I am planning an update for my standard lens for my Pentax K-5. As the Pentax DA* 16-50 is too expensive for me at this point and because the reviews of this lens are not that positive, I am looking at alternatives. Due to my limited budget, I have come up with two alternatives:



1. Tamron 17-50 2.8 non-VC (old version) €314

Pro's: - 17 mm wide

- Corner resolution is pretty good, even at f2.8

- Very positive reviews here and elsewhere

Con's: - Build quality

- AF noise

- Quality control issues



2. Sigma 18-50 2.8 EX DC Macro €349

Pro's: - I expect better build quality than the Tamron

- AF is supposedly much more quiet than the Tamron

Con's: - 18 mm wide, but actually -according to some reviews- it is close to 19 mm in real life

- Resolution of the borders at large apertures is dissapointing, need to stop down to f5.6



I just have difficulty to choose between these lenses. My reason to buy this lens is low light photography and portraits and off course IQ. I have to say that I really appreciate good built quality and that I do not mind AF noise, but it is nice if the noise is not too disturbing. Another question I would like to ask is how I can test these lenses in the shops for decentering or other QC issues. I mean they do not have a brick wall inside and most of the shops here in the Netherlands are situated in industry parks where it is very hard to find a brick wall in the first place. I was planning on taking a newspaper with me to test if the focus accuracy is decent.



Thanks for all your help!

[/quote]



Is it possible for you to try both lenses yourself?



People who have tried them side by side uniformly say that the Sigma is their favorite. A bit more contrasty, less CA wide open, and sharpness is not a let down for that Sigma.



About the AF noise, I know that for the Canon mount both lenses have motors inside the lens, and that there the Sigma is better (both noise wise and speed wise). And is more accurate. But I do not know if that is the same on Pentax... do they have their own motor for Pentax, or do they use the in-body motor (as I have always thought they are)?

If they use the in-body motor, I think the Sigma and Tamron will not show the difference you see for the Canon mount.



The Sigma is better built too, and it offers a closer MFD.
#3
[quote name='Brightcolours' timestamp='1300103084' post='6741']

Is it possible for you to try both lenses yourself?



People who have tried them side by side uniformly say that the Sigma is their favorite. A bit more contrasty, less CA wide open, and sharpness is not a let down for that Sigma.



About the AF noise, I know that for the Canon mount both lenses have motors inside the lens, and that there the Sigma is better (both noise wise and speed wise). And is more accurate. But I do not know if that is the same on Pentax... do they have their own motor for Pentax, or do they use the in-body motor (as I have always thought they are)?

If they use the in-body motor, I think the Sigma and Tamron will not show the difference you see for the Canon mount.



The Sigma is better built too, and it offers a closer MFD.

[/quote]



Thank you very much for your quick answer! Unfortunately I can not try both lenses side by side as the Sigma is officially discontinued and I have found only one shop in the Netherlands that still has the Sigma with the Pentax mount in stock. But they do not have the Pentax version of the Tamron lens, so I have to try that one somewhere else.



In my understanding both lenses are focussed by the in-camera motor of the Pentax K-5 via the slotted drive in the mount. However, there can still be a significant difference in the AF noise, as the mechanics in the lens (gears etc.) generate their own noise.



I have indeed read that the second version of the Sigma (the Macro version) has indeed good control of CA in contrast to the Tamron which has quite hefty CA at 17 mm. But what worries me is the border sharpness of the Sigma, I mean for portraits it would not matter that much, but shooting a scene indoors in low light might be a problem if I have to stop down to f5.6 to get decent borders.
#4
[quote name='Lampo' timestamp='1300102110' post='6739']

Currently I am planning an update for my standard lens for my Pentax K-5. As the Pentax DA* 16-50 is too expensive for me at this point and because the reviews of this lens are not that positive, I am looking at alternatives. Due to my limited budget, I have come up with two alternatives:



1. Tamron 17-50 2.8 non-VC (old version) €314

Pro's: - 17 mm wide

- Corner resolution is pretty good, even at f2.8

- Very positive reviews here and elsewhere

Con's: - Build quality

- AF noise

- Quality control issues



2. Sigma 18-50 2.8 EX DC Macro €349

Pro's: - I expect better build quality than the Tamron

- AF is supposedly much more quiet than the Tamron

Con's: - 18 mm wide, but actually -according to some reviews- it is close to 19 mm in real life

- Resolution of the borders at large apertures is dissapointing, need to stop down to f5.6



I just have difficulty to choose between these lenses. My reason to buy this lens is low light photography and portraits and off course IQ. I have to say that I really appreciate good built quality and that I do not mind AF noise, but it is nice if the noise is not too disturbing. Another question I would like to ask is how I can test these lenses in the shops for decentering or other QC issues. I mean they do not have a brick wall inside and most of the shops here in the Netherlands are situated in industry parks where it is very hard to find a brick wall in the first place. I was planning on taking a newspaper with me to test if the focus accuracy is decent.



Thanks for all your help!

[/quote]



I'd definitely go for the Tamron.

Sharpness-wise it's by far the best lens among the two. Even wide-open it performs very well. The Sigma doesn't impress in terms of IQ.

A good compromise, from what you wrote, would be the new Sigma 17-50 f/2.8. However, it's much more pricey.



Have you also considered the old Sigma 17-70 f/2.8-4.5? It's an extremely versatile lens, with longer range and pseudo macro ability (you can focus on stuff touching the front element!).

It's my walk-abound lens of choice and I also own a DA* 16-50. My Sigma copy is better optically.

What most people don't know is that the Sigma is f/2.8 from 17 to 21mm which is nice for interior shots.



Anyway, just my 2 cents.
--Florent

Flickr gallery
#5
[quote name='Lampo' timestamp='1300104230' post='6742']

Thank you very much for your quick answer! Unfortunately I can not try both lenses side by side as the Sigma is officially discontinued and I have found only one shop in the Netherlands that still has the Sigma with the Pentax mount in stock. But they do not have the Pentax version of the Tamron lens, so I have to try that one somewhere else.



In my understanding both lenses are focussed by the in-camera motor of the Pentax K-5 via the slotted drive in the mount. However, there can still be a significant difference in the AF noise, as the mechanics in the lens (gears etc.) generate their own noise.



I have indeed read that the second version of the Sigma (the Macro version) has indeed good control of CA in contrast to the Tamron which has quite hefty CA at 17 mm. But what worries me is the border sharpness of the Sigma, I mean for portraits it would not matter that much, but shooting a scene indoors in low light might be a problem if I have to stop down to f5.6 to get decent borders.

[/quote]

Honestly, I do not think you have to worry about the borders, they are not very soft.

Take a look at pixel peeper, I selected any f2.8 shots from the 18-50 (the macro and non-macro version shots will be mixed as they do not have different entries for both models). Via the links you can find bigger versions of the images in flickr.



I would confidently choose the Sigma myself (I have neither, I bought the original 18-50mm f2.8 EX DC years ago and it is good enough for me, as I do not use standard zoom a lot and it actually gives surprisingly good results still).
#6
Thanks! Yes, I have considered the Sigma 17-70 f2.8-4.5, but it is not available in the Netherlands anymore. The new 17-70 f2.8-4 OS HSM is considered less optically than the lens you have and it is also more expensive than the Sigma or Tamron that I am planning to buy with prices of €400,-. And I like the constant aperture of the lenses that I am considering, because it gives me more flexibility indoors when shooting portraits. Your opinion of the Sigma 18-50 2.8, is that based on the old version (67 mm filter thread) or the updated Macro version (72 mm filter thread)? There is a substantial difference in image quality between these two but they are mixed up constantly in reviews. The Macro version is in fact pretty similar to the 17-70 f2.8-4.5.



In an ideal world (which means I do not have a strict budget) I would probably go for the new Sigma 17-50 2.8, but with the prices in the Netherlands hovering somewhere around €600,- it is almost twice as expensive as the Tamron and that is a difference which I can not justify at this moment.
#7
[quote name='thxbb12' timestamp='1300106686' post='6747']

I'd definitely go for the Tamron.

Sharpness-wise it's by far the best lens among the two. Even wide-open it performs very well. The Sigma doesn't impress in terms of IQ.

A good compromise, from what you wrote, would be the new Sigma 17-50 f/2.8. However, it's much more pricey.



Have you also considered the old Sigma 17-70 f/2.8-4.5? It's an extremely versatile lens, with longer range and pseudo macro ability (you can focus on stuff touching the front element!).

It's my walk-abound lens of choice and I also own a DA* 16-50. My Sigma copy is better optically.

What most people don't know is that the Sigma is f/2.8 from 17 to 21mm which is nice for interior shots.



Anyway, just my 2 cents.

[/quote]

That is not really true, what you say. People who actually tried both lenses side by side always are more impressed with the IQ from the Sigma.



Try one yourself, if that is possible?



Sharpness wise... Funny enough on Pentax:

The Tamron is the worst performing here by far, a bit extreme. This Tamron clearly is not focussing correctly.

But it does match what people say who tried both (IQ of the Sigma better, and noticeacbly more contrasty). And it does show the Sigma to be plenty sharp!

http://www.pentaxforums.com/forums/penta...crops.html



Here a comparison that shows the exact same building scene, shot at the widest setting and wide open. The Sigma beats that Tamron sample by a big margin too.

http://www.dcfever.com/lens/readreview.php?id=2478



I don't own either lens myself, not a case of "my lens is better than yours".
#8
[quote name='Brightcolours' timestamp='1300115438' post='6759']

That is not really true, what you say. People who actually tried both lenses side by side always are more impressed with the IQ from the Sigma.



Try one yourself, if that is possible?



Sharpness wise... Funny enough on Pentax:

The Tamron is the worst performing here by far, a bit extreme. This Tamron clearly is not focussing correctly.

But it does match what people say who tried both (IQ of the Sigma better, and noticeacbly more contrasty). And it does show the Sigma to be plenty sharp!

http://www.pentaxforums.com/forums/penta...crops.html



Here a comparison that shows the exact same building scene, shot at the widest setting and wide open. The Sigma beats that Tamron sample by a big margin too.

http://www.dcfever.com/lens/readreview.php?id=2478



I don't own either lens myself, not a case of "my lens is better than yours".

[/quote]



Well, I've never tried the Sigma 18-50, but from this very website the IQ is not as good as the Tamron.

Also, the thread you point out on pentaxforums seems to be a case of FF issue.

The Tamron is generally considered to be one of the best f/2.8 standard zooms for sharpness. However it seems to be more prone to focus issues than the Sigma.

This being said, I know nothing of the new Sigma 18-50 with HSM. Perhaps they improved the IQ?
--Florent

Flickr gallery
#9
[quote name='thxbb12' timestamp='1300141374' post='6775']

Well, I've never tried the Sigma 18-50, but from this very website the IQ is not as good as the Tamron.

Also, the thread you point out on pentaxforums seems to be a case of FF issue.

The Tamron is generally considered to be one of the best f/2.8 standard zooms for sharpness. However it seems to be more prone to focus issues than the Sigma.

This being said, I know nothing of the new Sigma 18-50 with HSM. Perhaps they improved the IQ?

[/quote]

Not even this verey website has showed that the Tamron is "better". The lenses have been tested with a lot of time between them.

It is just that just about everyone who has tried them side by side perfers, on the whole, the Sigma.



The HSM version is Nikon only, and has not changed optically. The Nikon version relied on the Nikon internal motor, hence the update for the Nikon mount version later, with HSM (D40/40x/60/3000/3100/5000 all lost the Nikon internal motor).



The Canon version kept its old motor, and the Pentax version remained motorless.



To recap:

People who have used both comment on the better, more silent and more accurate AF from the Sigma. They comment on a better IQ on the whole, specifically at wide angle (less CA problems and more contrasty). Also the better build and closer focus are seen as plusses.



The side by side samples to be found never show the Sigma to be inferior.



The Tamron is a lens which is good, but has a reputation it not really deserves.
#10
Hmmm, interesting discussion. But I guess it is more important that I buy a good copy of either the Sigma or the Tamron, as a good Tamron will probably beat a bad Sigma and vice versa.



So than remains my second question: how do you test such a lens in a shop in an industry park without brick walls? My guess is f2.8, find a flat textured surface of some sort and shoot from a reasonable distance at different focal lengths and than analyse the photos in the centre, the border and the outerborder. Hopefully this will show decentering for instance. And I guess a newspaper will help to analyse focus accuracy. Is there anything you can add? Or is it the wrong set-up?
  


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