Worth Taking a Risk on the DA 20-40 Limited?

JinDesu · 12-05-2014, 01:36 PM

I've shot Sigma HSM lenses and they are quicker. But that being said, they are different.

The hood/lens cap is silly, I completely agree. I love the metal lens cap and felt lining, but not being able to use it without the hood...

But the lens feels so good to the touch that I don't care~

bdery · 12-05-2014, 02:16 PM

Originally posted by ogl

Old FA20-35 has no AF issues and has sharper corners than 20-40.

That's not surprising given that the FA is a full-frame lens.

VisualDarkness · 12-05-2014, 02:33 PM

It is for sure not slower than my DA* 55mm F1.4 and has worked quite decisive and accurately all the times I've tried one. I would buy it as a WR silent walkaround lens, currently my 55mm is that lens.

krebsy75 · 12-05-2014, 02:36 PM

Originally posted by VisualDarkness

It is for sure not slower than my DA* 55mm F1.4 and has worked quite decisive and accurately all the times I've tried one. I would buy it as a WR silent walkaround lens, currently my 55mm is that lens.

Comparing it to the 55mm in terms of AF is a pretty low bar. I would have been happy with 18-135 performance in this area.

The 20-40s AF isn't terrible. It just wasn't what you would expect for $999. The competition's newer glass has pretty zippy AF motors.

VisualDarkness · 12-05-2014, 02:48 PM

Originally posted by krebsy75

Comparing it to the 55mm in terms of AF is a pretty low bar. I would have been happy with 18-135 performance in this area.

The 20-40s AF isn't terrible. It just wasn't what you would expect for $999. The competition's newer glass has pretty zippy AF motors.

Yes, but I just wanted to point out that it's not even close to the slowest one.

The Problem with Pentax in-lens motors seems to be that they seem to lack torque due to the slow starting and switching of focusing direction in the lenses. It would partly explain the SDM issues too since a too weak motor is more likely to wear out too quickly and get stuck on any kind of dust or similar way more easily. Dunno where Pentax source their motors from? They pretty much got the weakest in-lens AF motors on the market.

JinDesu · 12-05-2014, 06:41 PM

Album of sample shots here: https://www.flickr.com/photos/jindesu/sets/72157649616280071/
Will add more over time. Currently the album has a set of 20mm, 30mm, and 40mm wide open shots (and a 20mm F5.6) showing the focus on the center and on the corner. Each photo is titled appropriately, and I include a full size image link in the comments so you can actually look through them.

Based on my images, I will say that my lens is sharp in the center wide open at all focal lengths. It is weakest in the corners at 30mm, and very good at 40mm. At 20mm, the corner is softer than the center, but at F5.6, it catches up well - so stopped down I cannot ever see someone saying my lens is "soft" in the corners.

The images are processed in Lightroom 5 from DNG files shot on my k-3 at ISO 100 (see the flickr, it shows the settings) on a tripod, manually focused on live-view, with no added sharpening or clarity or contrast. Only some brightness was added to get them to the same-ish level (corners have vignetting). I'll post the photos (and my subsequent evening/rain photos) into the appropriate thread, but I thought my links would be helpful to people trying to understand whether the DA 20-40 is worth it.

https://www.flickr.com/photos/jindesu/15768420278/in/set-72157649616280071

https://www.flickr.com/photos/jindesu/15336201783/in/set-72157649616280071/

https://www.flickr.com/photos/jindesu/15768420358/in/set-72157649616280071/

Again, album is here: https://www.flickr.com/photos/jindesu/sets/72157649616280071/
It contains more than just the 3 images above. I always provide full size links in my photos.

Nick Siebers · 12-06-2014, 09:54 AM

Originally posted by ogl

Yes. It's just my first impressions. But sharpness is only in one range. 20-29 or 30-40. And sharpness only in centre.

---------- Post added 12-05-2014 at 12:12 PM ----------

I have no any issues with all my lenses. FA20-35/4 is better than 20-40 was. Old FA20-35 has no AF issues and has sharper corners than 20-40.

I just picked up a DA 20-40, and tested against my FA 20-35. Wide open the DA was better at 20mm, the FA better at 35mm, most noticeable in the center. Stopped down, they all looked pretty much the same. Corners looked pretty similar, maybe better for the DA. It may vary by lens.

Last edited by Nick Siebers; 12-06-2014 at 10:00 AM.

ogl · 12-06-2014, 11:35 AM

Originally posted by Nick Siebers

I just picked up a DA 20-40, and tested against my FA 20-35. Wide open the DA was better at 20mm, the FA better at 35mm, most noticeable in the center. Stopped down, they all looked pretty much the same. Corners looked pretty similar, maybe better for the DA. It may vary by lens.

Wide-opened in center - yes. But if have a look at resolution at 5.6-8 at center and at the corners (especially) - no.
Plus - FA20-35/4 is 3 times cheaper for me.

Better corners for DA? It's unbelievable.

Nick Siebers · 12-06-2014, 12:01 PM

Originally posted by ogl

Wide-opened in center - yes. But if have a look at resolution at 5.6-8 at center and at the corners (especially) - no.
Plus - FA20-35/4 is 3 times cheaper for me.

Better corners for DA? It's unbelievable.

Well, I only ran one test, and focus could have been an issue. Plus I was getting some strange artifact. But what I described is what I found.

Marktax · 12-06-2014, 10:27 PM

Originally posted by someguy42

If I want to attach a filter, I have to unscrew the hood ring first. Since it's such a stellar performer in direct sunlight, the hood ring is just about worthless; I'd like to just leave the ring off permanently and find it a home in my bag, but then the lens cap wouldn't fit. I guess I'm going to have to find a 55mm plastic lens cap to stick on the end of it.

I think it's a nice hood and cap, but for travel I'm using a 55mm normal cap and leaving the hood at home. Would not want to lose it or drop it. A 55mm rubber collapsible would do nicely for travel too.

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12-05-2014, 01:36 PM	#46
JinDesu Veteran Member Join Date: Jun 2011 Location: New York City Photos: Gallery Posts: 5,638	I've shot Sigma HSM lenses and they are quicker. But that being said, they are different. The hood/lens cap is silly, I completely agree. I love the metal lens cap and felt lining, but not being able to use it without the hood... But the lens feels so good to the touch that I don't care~

12-05-2014, 02:16 PM	#47
bdery Pentaxian Join Date: Mar 2008 Location: Quebec city, Canada Photos: Gallery Posts: 9,357	Originally posted by ogl Old FA20-35 has no AF issues and has sharper corners than 20-40. That's not surprising given that the FA is a full-frame lens.

12-05-2014, 02:33 PM	#48
VisualDarkness Veteran Member Join Date: Nov 2011 Location: Uppsala, Sweden Photos: Gallery Posts: 4,439	It is for sure not slower than my DA* 55mm F1.4 and has worked quite decisive and accurately all the times I've tried one. I would buy it as a WR silent walkaround lens, currently my 55mm is that lens.

12-05-2014, 02:36 PM	#49
krebsy75 Veteran Member Join Date: Jun 2010 Location: Chester County, Pa. Posts: 804	Originally posted by VisualDarkness It is for sure not slower than my DA* 55mm F1.4 and has worked quite decisive and accurately all the times I've tried one. I would buy it as a WR silent walkaround lens, currently my 55mm is that lens. Comparing it to the 55mm in terms of AF is a pretty low bar. I would have been happy with 18-135 performance in this area. The 20-40s AF isn't terrible. It just wasn't what you would expect for $999. The competition's newer glass has pretty zippy AF motors.

12-05-2014, 02:48 PM	#50
VisualDarkness Veteran Member Join Date: Nov 2011 Location: Uppsala, Sweden Photos: Gallery Posts: 4,439	Originally posted by krebsy75 Comparing it to the 55mm in terms of AF is a pretty low bar. I would have been happy with 18-135 performance in this area. The 20-40s AF isn't terrible. It just wasn't what you would expect for $999. The competition's newer glass has pretty zippy AF motors. Yes, but I just wanted to point out that it's not even close to the slowest one. The Problem with Pentax in-lens motors seems to be that they seem to lack torque due to the slow starting and switching of focusing direction in the lenses. It would partly explain the SDM issues too since a too weak motor is more likely to wear out too quickly and get stuck on any kind of dust or similar way more easily. Dunno where Pentax source their motors from? They pretty much got the weakest in-lens AF motors on the market.

12-05-2014, 06:41 PM	#51
JinDesu Veteran Member Join Date: Jun 2011 Location: New York City Photos: Gallery Posts: 5,638	Album of sample shots here: https://www.flickr.com/photos/jindesu/sets/72157649616280071/ Will add more over time. Currently the album has a set of 20mm, 30mm, and 40mm wide open shots (and a 20mm F5.6) showing the focus on the center and on the corner. Each photo is titled appropriately, and I include a full size image link in the comments so you can actually look through them. Based on my images, I will say that my lens is sharp in the center wide open at all focal lengths. It is weakest in the corners at 30mm, and very good at 40mm. At 20mm, the corner is softer than the center, but at F5.6, it catches up well - so stopped down I cannot ever see someone saying my lens is "soft" in the corners. The images are processed in Lightroom 5 from DNG files shot on my k-3 at ISO 100 (see the flickr, it shows the settings) on a tripod, manually focused on live-view, with no added sharpening or clarity or contrast. Only some brightness was added to get them to the same-ish level (corners have vignetting). I'll post the photos (and my subsequent evening/rain photos) into the appropriate thread, but I thought my links would be helpful to people trying to understand whether the DA 20-40 is worth it. https://www.flickr.com/photos/jindesu/15768420278/in/set-72157649616280071 https://www.flickr.com/photos/jindesu/15336201783/in/set-72157649616280071/ https://www.flickr.com/photos/jindesu/15768420358/in/set-72157649616280071/ Again, album is here: https://www.flickr.com/photos/jindesu/sets/72157649616280071/ It contains more than just the 3 images above. I always provide full size links in my photos.

12-06-2014, 09:54 AM	#52
Nick Siebers Veteran Member Join Date: Jun 2008 Location: Madison, WI Photos: Gallery \| Albums Posts: 2,165	Originally posted by ogl Yes. It's just my first impressions. But sharpness is only in one range. 20-29 or 30-40. And sharpness only in centre. ---------- Post added 12-05-2014 at 12:12 PM ---------- I have no any issues with all my lenses. FA20-35/4 is better than 20-40 was. Old FA20-35 has no AF issues and has sharper corners than 20-40. I just picked up a DA 20-40, and tested against my FA 20-35. Wide open the DA was better at 20mm, the FA better at 35mm, most noticeable in the center. Stopped down, they all looked pretty much the same. Corners looked pretty similar, maybe better for the DA. It may vary by lens. Last edited by Nick Siebers; 12-06-2014 at 10:00 AM.

12-06-2014, 11:35 AM	#53
ogl Banned Join Date: Dec 2007 Location: Sankt Peterburg Photos: Gallery \| Albums Posts: 8,382	Originally posted by Nick Siebers I just picked up a DA 20-40, and tested against my FA 20-35. Wide open the DA was better at 20mm, the FA better at 35mm, most noticeable in the center. Stopped down, they all looked pretty much the same. Corners looked pretty similar, maybe better for the DA. It may vary by lens. Wide-opened in center - yes. But if have a look at resolution at 5.6-8 at center and at the corners (especially) - no. Plus - FA20-35/4 is 3 times cheaper for me. Better corners for DA? It's unbelievable.

12-06-2014, 12:01 PM	#54
Nick Siebers Veteran Member Join Date: Jun 2008 Location: Madison, WI Photos: Gallery \| Albums Posts: 2,165	Originally posted by ogl Wide-opened in center - yes. But if have a look at resolution at 5.6-8 at center and at the corners (especially) - no. Plus - FA20-35/4 is 3 times cheaper for me. Better corners for DA? It's unbelievable. Well, I only ran one test, and focus could have been an issue. Plus I was getting some strange artifact. But what I described is what I found.

12-06-2014, 10:27 PM	#55
Marktax Pentaxian Join Date: Jun 2013 Location: Washington DC Photos: Albums Posts: 610	Originally posted by someguy42 If I want to attach a filter, I have to unscrew the hood ring first. Since it's such a stellar performer in direct sunlight, the hood ring is just about worthless; I'd like to just leave the ring off permanently and find it a home in my bag, but then the lens cap wouldn't fit. I guess I'm going to have to find a 55mm plastic lens cap to stick on the end of it. I think it's a nice hood and cap, but for travel I'm using a 55mm normal cap and leaving the hood at home. Would not want to lose it or drop it. A 55mm rubber collapsible would do nicely for travel too.