Bad review for DA* 16-50mm


m42geo

Link Posted 12/10/2011 - 09:59
K10D wrote:

The Sigma is an excellent lens as is the Pentax. I did miss the extra 1mm shorter length of the SDM whilst using the sigma.

Best regards

How does the build quality does the pentax compare to the sigma? You think in term of image quality they are both just as good?

GlynM

Link Posted 12/10/2011 - 10:08
With the DA*16-50 I definitely sit on the fence. In my experience it can produce some excellent results but does have some limitations which have occasionally caught me out.

I have had three of these. The first, a very early one delivered in August 2007, was effectively DOA with duff SDM and was replaced after about a month.

The replacement was actually an earlier serial number, probably the shop's demo copy as stock was almost impossible to get at that time. It's SDM was fine but it was definitely soft wide open which caused problems with auto focus not working, particularly with landscapes for which otherwise the lens is an excellent choice. Unfortunately, similar to George, I destroyed this lens in a fall. I did though like this lens enough to buy another one, number 3 in July 2009.

Number 3 had SDM failure after about 9 months. It was repaired under warranty in June 2010. It has been working fine since then and hopefully has the later, more powerful, SDM motor.

I didn't have the first one long enough to test properly but with the other two I did & do occasionally have problems with lens flare. Certainly you can expect this when pointing straight into the sun, e.g. sunsets, but I have seen off-direct-line flare, not seen through the viewfinder, which has caught me out a couple of times.

A problem I have noticed with number 3 is colour fringing. Here is an example of a family gathering, my father's 80th birthday, shot in possibly difficult lighting conditions late in the day back in April. I have added a couple of 100% crops as an example of the colour fringing that was present across the whole shot. I know it was fairly simple to correct in PP but it was just extra work that I didn't expect to have to do:

K-7 with DA*16-50 @ 16mm, 1/30sec, F11, ISO 200 with D-range highlight comp on & D-Range shadows comp high.










As you might notice, from the fence posts, distortion at 16mm is also a slight issue.

I found the SDM failure on what was my most expensive lens purchases a big disappointment and I have not bought another Pentax SDM lens. I would certainly not recommend buying a SDM lens 2nd hand. I would want the full 2 year warranty you get on a new purchase from Pentax-Pro dealers.

When number 3 started having SDM problems I did buy a Sigma 17-70 1:2.8-4 HSM OS lens. Its HSM works very well and I tend to use it when I go out on my bike mainly because I don't want to risk breaking another 16-50 . My impression is that it is a little bit softer than my number 3 16-50 but otherwise I am very pleased with it.

Glyn
Last Edited by GlynM on 12/10/2011 - 10:29

ChrisA

Link Posted 12/10/2011 - 10:39
Was the image captured as a JPG?

I notice from the EXIF on that group shot that you've got contrast and sharpness both set to 'hard'.

I wonder if that exacerbates the effect of the CA you refer to.

I can see what you mean about the fence posts, but I don't think that's lens distortion. I think that's converging verticals, caused by pointing the camera down a bit.

The wider the angle, the more obvious this will be if the lens axis isn't parallel to the ground.
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Pentax K-3, DA18-135, DA35 F2.4, DA17-70, DA55-300, FA28-200, A50 F1.7, A100 F4 Macro, A400 F5.6, Sigma 10-20 EXDC, 50-500 F4.5-6.3 APO DG OS Samsung flash SEF-54PZF(x2)
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m42geo

Link Posted 12/10/2011 - 10:51
GlynM

Thanks for the sample and review.

If I am going to buy the 16-50 I am going to use it for work so I need top quality lens, I currently have the sigma 18-50 2.8 EX and I also doesn't like this wide open too much, and auto focus is low light condition is a big big problem. When I try to shoot at the wider end at low light it always off focus by miles and distortion is also a big problem shooting in my small studio. I was hoping the DA 16-50 can solve such problems however after looking at your examples seems that CA is a big problem. I guess I just have to wait for pentax bring out the 16-50 mark II.

Just want to post a full size original image that shot with my sigma 18-50 and see if any DA 16-50 user think that the DA* can perform better in term of sharpness.

Thanks

click to see 100% full size



GEO_4025 by geovienso, on Flickr

GlynM

Link Posted 12/10/2011 - 10:54
Hi Chris, it was shot JPEG. I very rarely go raw. Although this did not prevent me from correcting the colour fringe and distortion in the the Pentax DCU4 laboratory.

The contrast & sharpness being up one notch is what you get when you set the camera to "Bright" which is where I normally run it as I found "Natural" a bit bland on the K-7.

Using 16mm was a compromise. I started off longer but I wanted to be in the picture and I had to get the camera close enough for me to run & place myself in the group under a timer shot . Disappointing the remote didn't work at this distance.

Glyn

ChrisA

Link Posted 12/10/2011 - 11:04
GlynM wrote:
Hi Chris, it was shot JPEG. I very rarely go raw. Although this did not prevent me from correcting the colour fringe and distortion in the the Pentax DCU4 laboratory.

Forgive me, but I would take issue with the term 'distortion', since used in this way it falsely gives the impression that it's a lens problem.

You'd get converging verticals with the lens axis pointing down or up even with a perfect rectilinear lens, and it happens simply because with the camera pointing down, the top of the fence post is closer than the bottom, so it appears bigger.
.
Pentax K-3, DA18-135, DA35 F2.4, DA17-70, DA55-300, FA28-200, A50 F1.7, A100 F4 Macro, A400 F5.6, Sigma 10-20 EXDC, 50-500 F4.5-6.3 APO DG OS Samsung flash SEF-54PZF(x2)
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Last Edited by ChrisA on 12/10/2011 - 11:19

GlynM

Link Posted 12/10/2011 - 11:23
m42geo wrote:


If I am going to buy the 16-50 I am going to use it for work so I need top quality lens, I currently have the sigma 18-50 2.8 EX and I also doesn't like this wide open too much, and auto focus is low light condition is a big big problem. When I try to shoot at the wider end at low light it always off focus by miles and distortion is also a big problem shooting in my small studio. I was hoping the DA 16-50 can solve such problems however after looking at your examples seems that CA is a big problem. I guess I just have to wait for pentax bring out the 16-50 mark II.

For Protraits and other studio/indoor stuff I have never had any issues with the DA*16-50. I find that it excels at this. I have only experienced the colour fringing problem with out-side high-contrast stuff and then not often.


I came to my 1st DA*16-50 from a Sigma 18-50 F2.8 EX which I had bought as a step-up from the kit lens back in 2006. I was then into early morning landscapes and wanted the extra speed. I was very disappointed about the awful levels of purple fringing in the Sigma and was certainly for me an eye-opener particularly as none of the early reviews mentioned this.

You have to offset my grumbles with the DA*16-50 with the fact that I like it enough to have bought two them. Hopefully the SDM issues have been resolved with more powerful motors. Most of the time mine produces fantastic results. As with most of the lenes I have tried there is a learning process you have to go though so that you know where it performs its best and, perhaps, when to use something else or accept some compromise. Of course when you are getting old, like me, you have to remember it as well .

Glyn
Last Edited by GlynM on 12/10/2011 - 11:45

GlynM

Link Posted 12/10/2011 - 11:34
ChrisA wrote:

Forgive me, but I would take issue with the term 'distortion', since used in this way it falsely gives the impression that it's a lens problem.

You'd get converging verticals with the lens axis pointing down or up even with a perfect rectilinear lens, and it happens simply because with the camera pointing down, the top of the fence post is closer than the bottom, so it appears bigger.

No problem Chris I'm sure you are right. It was not helped in this shot living on the side of hill either . I think at the time I was trying to keep the tree in the middle straight and was just a bit surprised to see the order of difference between the extreme left & right fence posts.

Glyn

GlynM

Link Posted 12/10/2011 - 11:59
Just had a quick look for something recently shot inside with the DA* 16-50 and remembered this which is a non-posed shot of my grandson, around 4 weeks old, with him mum, having just been given a dose of gripe-water which disappointingly no longer contains any alcohol .


I have tinkered a bit with it in PSE but is was originally shot with a Pentax K-5 with DA*16-50 @ 50mm, 1/100 sec F4.5, ISO800, d-range highlight comp on and medium shadow comp, bright mode, using a bounce flash all hand-held.




Glyn
Last Edited by GlynM on 12/10/2011 - 12:03

ChrisA

Link Posted 12/10/2011 - 12:03
GlynM wrote:
No problem Chris I'm sure you are right. It was not helped in this shot living on the side of hill either . I think at the time I was trying to keep the tree in the middle straight and was just a bit surprised to see the order of difference between the extreme left & right fence posts.

Yes, it does look a little strange. Is the fence at the left further away than the fence on the right? It certainly looks so, if the fence panels are the same size If so, the effect will be more pronounced with the closer post.

Hopefully these diagrams will illustrate the point I'm making about the camera pointing down:







The wider-angle the lens, the closer you're likely to be, so the more exaggerated the effect appears.

Here are some shots I took at 10mm to illustrate this:

Camera horizontal:




Camera pointing down:




However, note the curved edges in the first house shot. My walls are really straight.

This is lens-induced distortion - known as barrel distortion.
.
Pentax K-3, DA18-135, DA35 F2.4, DA17-70, DA55-300, FA28-200, A50 F1.7, A100 F4 Macro, A400 F5.6, Sigma 10-20 EXDC, 50-500 F4.5-6.3 APO DG OS Samsung flash SEF-54PZF(x2)
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RayB

Link Posted 12/10/2011 - 12:33
As we are now posting examples, this was taken with the DA*16-50mm. Unposed, the subject (my niece) had been having a game of "dodge the lens" with me all day. It is not an image I was intending to do anything with, but I've found with this lens I do a lot less PP than with any of my others.




Sorry, can't seem to link to the image which is in the gallery....
Last Edited by RayB on 12/10/2011 - 12:36

GlynM

Link Posted 12/10/2011 - 12:35
ChrisA wrote:

Yes, it does look a little strange. Is the fence at the left further away than the fence on the right? It certainly looks so, if the fence panels are the same size If so, the effect will be more pronounced with the closer post.

I understand what you are getting at but it does seem a bit extreme. The camera was tripod mounted which I will have levelled but I may have been pointing the camera up or down a bit but not much.

I think the left-hand fence post was further away but again not much. The hill adds problems here and fence panels also get smaller in height.

I have just been out and had another look at the site. I took a quick, hand-held shot, standing up straight, of the site using a DA35 F2.8, so from further back and can't guarantee it was in the same line and elevation but it looks fine as long as you ignore the bird-bath :




Glyn
Last Edited by GlynM on 12/10/2011 - 12:36

ChrisA

Link Posted 12/10/2011 - 12:40
GlynM wrote:
The camera was tripod mounted which I will have levelled but I may have been pointing the camera up or down a bit but not much.

If your group shot above is the whole frame, you can see exactly where the camera was pointing. If it was mounted on the tripod higher than that, you'll get the effect.

It's surprising how little you need to see it.

At 35mm the effect is *much* less pronounced, since, as you say, you're further away.
.
Pentax K-3, DA18-135, DA35 F2.4, DA17-70, DA55-300, FA28-200, A50 F1.7, A100 F4 Macro, A400 F5.6, Sigma 10-20 EXDC, 50-500 F4.5-6.3 APO DG OS Samsung flash SEF-54PZF(x2)
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Last Edited by ChrisA on 12/10/2011 - 12:42

m42geo

Link Posted 12/10/2011 - 12:43
GlynM

Can you please post a full size image of your grandson? thanks

K10D

Link Posted 12/10/2011 - 12:45
m42geo wrote:
K10D wrote:

The Sigma is an excellent lens as is the Pentax. I did miss the extra 1mm shorter length of the SDM whilst using the sigma.

Best regards

How does the build quality does the pentax compare to the sigma? You think in term of image quality they are both just as good?

These shots with the Sigma OS @ 17mm, hand held.







these with the SDM




@16mm showing slight distortion.




Both good lenses. As for build quality, the SDM has the edge and is smoother in operation. The OS on the Sigma seems to be better than the in-body SR (imo).

Best regards
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