Should I keep it or exchange for something else?

dr_romix · 11-12-2011, 12:26 PM

Originally posted by excanonfd

If you are going out to shoot, why not take the 17-70 with you as well? You can't tell without actually shooting with the lens, I don't shoot with mine anymore since SDM failure but I found the images acceptable across the aperture range. Your own pictures will tell you more about the lens than any of us can describe the characteristics of the 17-70. But if you are bent on returning the lens for something else without actually shooting with it, do it.

I'm taking it with me.. let's c who wins... will keep it posted...

GSk · 11-12-2011, 12:56 PM

Hi

I've had the Sigma 17 - 70 with Pentax mount, never tried the Pentax 17 - 70.

Sigma was a good lens, but it is not a decent macro. And it is f2.8 only on the really wide end, so this number is not much but a gimmick. At focal lenght 70mm the Pentax has f4 while the Sigma has f4.5.

philbaum · 11-12-2011, 01:00 PM

Go try it - how long does it take : 1/1000s

I'd keep it unless it was defective - i've always thought that lens was a nice range. Friendships are important

dr_romix · 11-12-2011, 02:20 PM

OK. I did a few shots with this lens including some head shot. I also used my DA* 50-135 and Tamron 28-75. When it comes to portrait, DA* is the winner where Tamron comes 2nd.

Color rendering is great but it has horrible Purple fringing at wide end 17mm f/7.1 and even at 25mm f/9.

Last edited by dr_romix; 11-12-2011 at 05:00 PM.

dr_romix · 11-12-2011, 04:59 PM

Pentax K-5 ISO100 25mm f/4 1/125sec look at purple fringing on both corner 100% cropped. it's even obvious at f/9. Am I having a bad copy or is this normal ?

mgroves27 · 11-12-2011, 05:03 PM

Keep it!

dr_romix · 11-12-2011, 05:07 PM

25mm f/9 ISO200 1/100 Sec

Attached Images

excanonfd · 11-12-2011, 06:36 PM

What lens doesn't purple fringe at such extreme contrast range? Does the other lenses in your stable fare any better? Your signature show you have the focal length range of the DA 17-70 covered, perhaps it is a good idea to trade it for a macro or another prime lens.

dr_romix · 11-12-2011, 07:08 PM

Originally posted by GSk

Hi

I've had the Sigma 17 - 70 with Pentax mount, never tried the Pentax 17 - 70.

Sigma was a good lens, but it is not a decent macro. And it is f2.8 only on the really wide end, so this number is not much but a gimmick. At focal lenght 70mm the Pentax has f4 while the Sigma has f4.5.

The newer sigma at FL 70mm has f/4..

17-70mm F2.8-4.5 DC Macro - Standard Zoom Lenses - SigmaPhoto.com

dr_romix · 11-12-2011, 07:25 PM

with Pentax 17-70. color contrast and bokah looks lot better before upload. The only thing that bothers me is its horrible PF.

wlachan · 11-12-2011, 07:28 PM

Looks like your DA17-70/4 is a good sample and sharp wide open. I would just keep it and protect it from any physical impact. PF of your samples is actually quite good by Pentax standard. I can assure you many of my FA primes are far worse.

dr_romix · 11-13-2011, 05:47 AM

Originally posted by excanonfd

What lens doesn't purple fringe at such extreme contrast range? Does the other lenses in your stable fare any better? Your signature show you have the focal length range of the DA 17-70 covered, perhaps it is a good idea to trade it for a macro or another prime lens.

I wanna have something for walkaround rather than switching lenses...

dr_romix · 11-13-2011, 05:58 AM

3 more with Pentax 17-70. what do you guys think?

creampuff · 11-13-2011, 06:23 AM

I got the DA 17-70mm and I think it's a nice lens. Keep it.

excanonfd · 11-13-2011, 11:46 AM

Originally posted by dr_romix

3 more with Pentax 17-70. what do you guys think?

The question is what do YOU think? First you were all for trading it in but now it seems you are not so sure. You seemed to think f4.0 was too slow but a faster zoom is only one stop faster and with your K-5 that one stop difference becomes negligible. I am shooting K20D and I've never thought a constant f4.0 as being slow. DA 17-70 is a good lens, sharpness is pretty even between the centre and the corner. Sigma is sharp in the centre but not as good in the corners and even when stopped down Sigma has significant difference between the centre and the corner sharpness (a general characteristic of most Sigma lenses). I bought mine for the same reason that you seem to want to keep the lens now - don't want to change lenses (4x zoom coverage) as a replacement for my Sigma 18-125. If I did not encounter SDM failure with the lens, I'd still be using it now.

11-12-2011, 12:56 PM	#17
GSk Inactive Account Join Date: Jan 2008 Location: Sørumsand, Norway Photos: Gallery \| Albums Posts: 59	Sigma or Pentax 17 - 70 Hi I've had the Sigma 17 - 70 with Pentax mount, never tried the Pentax 17 - 70. Sigma was a good lens, but it is not a decent macro. And it is f2.8 only on the really wide end, so this number is not much but a gimmick. At focal lenght 70mm the Pentax has f4 while the Sigma has f4.5.

11-12-2011, 04:59 PM	#20
dr_romix Banned Join Date: May 2011 Location: Pittsburgh,PA Posts: 321 Original Poster	Pentax K-5 ISO100 25mm f/4 1/125sec look at purple fringing on both corner 100% cropped. it's even obvious at f/9. Am I having a bad copy or is this normal ? Attached Images

11-12-2011, 07:25 PM	#25
dr_romix Banned Join Date: May 2011 Location: Pittsburgh,PA Posts: 321 Original Poster	with Pentax 17-70. color contrast and bokah looks lot better before upload. The only thing that bothers me is its horrible PF. Attached Images

11-13-2011, 05:58 AM	#28
dr_romix Banned Join Date: May 2011 Location: Pittsburgh,PA Posts: 321 Original Poster	3 more with Pentax 17-70. what do you guys think? Attached Images

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11-12-2011, 12:26 PM	#16
dr_romix Banned Join Date: May 2011 Location: Pittsburgh,PA Posts: 321 Original Poster	Originally posted by excanonfd If you are going out to shoot, why not take the 17-70 with you as well? You can't tell without actually shooting with the lens, I don't shoot with mine anymore since SDM failure but I found the images acceptable across the aperture range. Your own pictures will tell you more about the lens than any of us can describe the characteristics of the 17-70. But if you are bent on returning the lens for something else without actually shooting with it, do it. I'm taking it with me.. let's c who wins... will keep it posted...

11-12-2011, 01:00 PM	#18
philbaum Veteran Member Join Date: Oct 2007 Location: Port Townsend, Washington State, USA Posts: 3,659	Go try it - how long does it take : 1/1000s I'd keep it unless it was defective - i've always thought that lens was a nice range. Friendships are important

11-12-2011, 02:20 PM	#19
dr_romix Banned Join Date: May 2011 Location: Pittsburgh,PA Posts: 321 Original Poster	OK. I did a few shots with this lens including some head shot. I also used my DA* 50-135 and Tamron 28-75. When it comes to portrait, DA* is the winner where Tamron comes 2nd. Color rendering is great but it has horrible Purple fringing at wide end 17mm f/7.1 and even at 25mm f/9. Last edited by dr_romix; 11-12-2011 at 05:00 PM.

11-12-2011, 05:03 PM	#21
mgroves27 New Member Join Date: Dec 2009 Location: St. Louis Posts: 7	Keep it!

11-12-2011, 05:07 PM	#22
dr_romix Banned Join Date: May 2011 Location: Pittsburgh,PA Posts: 321 Original Poster	25mm f/9 ISO200 1/100 Sec Attached Images

11-12-2011, 06:36 PM	#23
excanonfd Veteran Member Join Date: Jan 2010 Location: Vancouver, BC Posts: 1,421	What lens doesn't purple fringe at such extreme contrast range? Does the other lenses in your stable fare any better? Your signature show you have the focal length range of the DA 17-70 covered, perhaps it is a good idea to trade it for a macro or another prime lens.

11-12-2011, 07:08 PM	#24
dr_romix Banned Join Date: May 2011 Location: Pittsburgh,PA Posts: 321 Original Poster	Originally posted by GSk Hi I've had the Sigma 17 - 70 with Pentax mount, never tried the Pentax 17 - 70. Sigma was a good lens, but it is not a decent macro. And it is f2.8 only on the really wide end, so this number is not much but a gimmick. At focal lenght 70mm the Pentax has f4 while the Sigma has f4.5. The newer sigma at FL 70mm has f/4.. 17-70mm F2.8-4.5 DC Macro - Standard Zoom Lenses - SigmaPhoto.com

11-12-2011, 07:28 PM	#26
wlachan Veteran Member Join Date: Sep 2006 Location: Canada Photos: Albums Posts: 2,625	Looks like your DA17-70/4 is a good sample and sharp wide open. I would just keep it and protect it from any physical impact. PF of your samples is actually quite good by Pentax standard. I can assure you many of my FA primes are far worse.

11-13-2011, 05:47 AM	#27
dr_romix Banned Join Date: May 2011 Location: Pittsburgh,PA Posts: 321 Original Poster	Originally posted by excanonfd What lens doesn't purple fringe at such extreme contrast range? Does the other lenses in your stable fare any better? Your signature show you have the focal length range of the DA 17-70 covered, perhaps it is a good idea to trade it for a macro or another prime lens. I wanna have something for walkaround rather than switching lenses...

11-13-2011, 06:23 AM	#29
creampuff Veteran Member Join Date: May 2007 Location: Singapore Photos: Gallery Posts: 3,953	I got the DA 17-70mm and I think it's a nice lens. Keep it.

11-13-2011, 11:46 AM	#30
excanonfd Veteran Member Join Date: Jan 2010 Location: Vancouver, BC Posts: 1,421	Originally posted by dr_romix 3 more with Pentax 17-70. what do you guys think? The question is what do YOU think? First you were all for trading it in but now it seems you are not so sure. You seemed to think f4.0 was too slow but a faster zoom is only one stop faster and with your K-5 that one stop difference becomes negligible. I am shooting K20D and I've never thought a constant f4.0 as being slow. DA 17-70 is a good lens, sharpness is pretty even between the centre and the corner. Sigma is sharp in the centre but not as good in the corners and even when stopped down Sigma has significant difference between the centre and the corner sharpness (a general characteristic of most Sigma lenses). I bought mine for the same reason that you seem to want to keep the lens now - don't want to change lenses (4x zoom coverage) as a replacement for my Sigma 18-125. If I did not encounter SDM failure with the lens, I'd still be using it now.