[luftfluss]

There are few detailed reviews of this lens.

One such review has been published on the French site Le Monde de la Photo: TEST HD Pentax-DA* 11-18 mm f/2.8, Le piqué - Le Monde de la Photo

They identified softness at the corners at the wide end (11 mm) and f/2.8, and "only good" sharpness at 11mm f/4. All other settings were rated at least "very good."

- Craig

It's interesting how the results from Le Monde de la Photo differ from the Chris & Jordan's review, besides comments on corner resolution.

In the DPR video, Chris describes the center sharpness as "sharp enough in the center, doesn't blow me away..."

While Le Monde de la Photo rates the center sharpness as "excellent" to "superlative", even wide open.

[house]

Its also worth remembering that the first shots with the lens we saw on this site. A brick building with whitish rustication flanked by turrets if I remember correctly. Had pretty sharp decline in resolution towards the edges. That decline in resolution was visible at low resolution AND did perfectly match the mtf curves when they were over laid. Other copies seem better but it's really hard to compare random shots. Optical downsides can come out in certain situations, I've found that it can take a while to find them.

In addition to the French review there's also this one. I rely on google translate for anything but the pictures
https://radojuva.com/2019/03/hd-pentax-da-star-11-18mm-ed-dc-aw/

[Mbaez]

I don't know if they had a bad sample or that lens needed an autofocus adjustment in their camera, but my copy is way sharper.

Here is a recent picture at f4 mounted on a K3:

Pentax 11-18 Long exposure | Marcos Baez | Flickr

[BigMackCam]

I don't know if they had a bad sample or that lens needed an autofocus adjustment in their camera, but my copy is way sharper.

Here is a recent picture at f4 mounted on a K3:

Pentax 11-18 Long exposure | Marcos Baez | Flickr

That's awesome... The corners look superb.

[Mbaez]

That's awesome... The corners look superb.

Thank you BigMacCam!
To be honest, this is my second and definitive sample. I returned the first one after someone in the forum noticed softness in one side.

[BruceBanner]

Could be a QC issue then. I have no idea how it happens, I'm sure they are tested before going out, do they get injured during transport and thus some copies are a little misaligned by the time they end up in the hands of the consumer?

[luftfluss]

Could be a QC issue then. I have no idea how it happens, I'm sure they are tested before going out, do they get injured during transport and thus some copies are a little misaligned by the time they end up in the hands of the consumer?

Don't be so sure. Many websites - Lenstip and OpticalLimits come to mind - actually buy or borrow some of the gear they test from individuals or stores.

[BruceBanner]

Don't be so sure. Many websites - Lenstip and OpticalLimits come to mind - actually buy or borrow some of the gear they test from individuals or stores.

No I mean, if DPR copy was soft in corners and we have @Mbaez saying it took a second copy of the lens to get a sharp corner version of the lens, that there is possibly a QC issue going on. Point being a lens review reviewing just one lens and not 2-3 copies of the same lens is perhaps just a pointless review period. What if they review a very bad copy? DPR state that given the pricetag QC issues is not really acceptable, but I'm wondering if there's anything that the manufacturer can do? Does it come out of the shop good and end up bad along the way vs being bad from the get go? Have you seen postal workers

[BigMackCam]

No I mean, if DPR copy was soft in corners and we have @Mbaez saying it took a second copy of the lens to get a sharp corner version of the lens, that there is possibly a QC issue going on. Point being a lens review reviewing just one lens and not 2-3 copies of the same lens is perhaps just a pointless review period. What if they review a very bad copy? DPR state that given the pricetag QC issues is not really acceptable, but I'm wondering if there's anything that the manufacturer can do? Does it come out of the shop good and end up bad along the way vs being bad from the get go? Have you seen postal workers

This is why, as I've said before, I never rely on just one review - no matter how trustworthy and dependable the source.

As for DPR saying QC anomalies are unacceptable at this price point, I actually agree with them. But the reality is, such problems are common across the mainstream lens makers. Lenses considerably more premium and costly than the DA*11-18/2.8 are still subject to copy variation...

[swanlefitte]

For perspective think about the Helios 44-2 reviews. There is a ton of copy variations and the worst are pretty bad. You think you might buy one. It's great to know you may not get a good lens. You don't buy a lens based on what a bad copy can do. You buy a lens for potential. I never thought to buy a lens on the basis of what a bad copy can do. I don't need a review of what a bad copy can do.

[BruceBanner]

This is why, as I've said before, I never rely on just one review - no matter how trustworthy and dependable the source.

As for DPR saying QC anomalies are unacceptable at this price point, I actually agree with them. But the reality is, such problems are common across the mainstream lens makers. Lenses considerably more premium and costly than the DA*11-18/2.8 are still subject to copy variation...

Yeah, and so I'm questioning the QC. Can a lens finish production as a good copy and somehow en route to the shop or customer become damaged in transportation and is now a bad copy? Who do we blame for that if this is the case? Postal service, the manufacturer? Seems unfair to blame Pentax for something that is outside of their domain of control is my point. But I don't know if that's possible (a good copy turns bad during rough treatment from factor>store>consumer).

[stevebrot]

Could be a QC issue then. I have no idea how it happens, I'm sure they are tested before going out, do they get injured during transport and thus some copies are a little misaligned by the time they end up in the hands of the consumer?

QA (different than QC) is sort of a strange game in that it is focused on process and sampling and not on final quality testing. As a result, final inspection is seldom thorough and a defined percentage of product will go out the door, technically "out of control" in one or more aspects. Rarely a product will be badly out-of-control. Whether the problem is severe enough to trigger a return or warranty service request depend on the purchaser and how demanding they are.

I will go out on a limb here and suggest that it would take a significant blow in transit to decenter a lens produced using modern manufacturing techniques and materials. After all, most of us never see a problem despite treating our camera gear no more carefully than we treat our lunch. Several of my lenses have been backpacked thousands of miles without special treatment other than the cases they came in. That said, given the resolution of today's sensors, many end users are in a better position to detect a decentered element than the final assembly inspectors. From reports on this site, it appears there is an epidemic of poorly aligned lenses, though I believe that the actual incidence is well within the QA targets set by the makers. I also suspect that the QA monitors are probably not sensitive enough and that a fairly large number of lenses with detectable decentering go out the door as OK.

The reason I say that is less rooted in user complaints of soft corners and more related to the high frequency of users seeking help with AF fine adjustment. One or more decentered elements along improper focus group adjustment are common causes of front/back focus in that such may cause the OOF image to AF sensor to be distorted and asymmetrical and ambiguous to the sensor.

Bottom line is that I am not too surprised by reports of someone getting two decentered lenses in two attempts to get a good one.


Steve

[clackers]

Well, Pentax Week came and went ... two videos?

[BigMackCam]

Well, Pentax Week came and went ... two videos?

Yes, I noticed that. Quite the event, wasn't it?

[Rondec]

QA (different than QC) is sort of a strange game in that it is focused on process and sampling and not on final quality testing. As a result, final inspection is seldom thorough and a defined percentage of product will go out the door, technically "out of control" in one or more aspects. Rarely a product will be badly out-of-control. Whether the problem is severe enough to trigger a return or warranty service request depend on the purchaser and how demanding they are.

I will go out on a limb here and suggest that it would take a significant blow in transit to decenter a lens produced using modern manufacturing techniques and materials. After all, most of us never see a problem despite treating our camera gear no more carefully than we treat our lunch. Several of my lenses have been backpacked thousands of miles without special treatment other than the cases they came in. That said, given the resolution of today's sensors, many end users are in a better position to detect a decentered element than the final assembly inspectors. From reports on this site, it appears there is an epidemic of poorly aligned lenses, though I believe that the actual incidence is well within the QA targets set by the makers. I also suspect that the QA monitors are probably not sensitive enough and that a fairly large number of lenses with detectable decentering go out the door as OK.

The reason I say that is less rooted in user complaints of soft corners and more related to the high frequency of users seeking help with AF fine adjustment. One or more decentered elements along improper focus group adjustment are common causes of front/back focus in that such may cause the OOF image to AF sensor to be distorted and asymmetrical and ambiguous to the sensor.

Bottom line is that I am not too surprised by reports of someone getting two decentered lenses in two attempts to get a good one.


Steve

I think decentering (at least some) with wide angle lenses is fairly common. Plenty of folks here have complained about soft corners on an Irix 15mm or the DFA 15-30. The only thing to do is to test a lens when you get it and see if it performs to expectation.

I will say that there seem to be significantly fewer problems these days than when the DA *16-50 was first released. That lens had huge problems with decentering issues and when the SDM started failing on it, people just completely gave up on it.