Sharpness problem with NEX SEL16F28 lens

[alphaomega]

I finally received my NEX-5 kit with 16mm pancake lens and SEL1855 Zoom. Went out to test the kit 22 and 23 December. The 18-55mm zoom appears to be good, but I was most disappointed by the 16mm lens. It is a bit like the bottom of a bottle. (a bit exaggerated). At F2.8 it is just unsharp all over. Stopping down a bit makes the centre sharper but whatever F stop I use it is unsharp both on r/h ald l/h of image (viewed at 100%). Right is worse than left. Very disappointed. As I have already sent away for my VATback and the NEX-5 and 18-55 seem fine I am sending the 16mm in for repair/replacement by Sony under warranty. Looking at some of the entries around the Net the 16mm is supposed to proform well enough so I may just have received a rogue copy. I recall David Kilpatrick saying some time ago that he had all his NEX-5 pictures accepted by Alamy and I assume that included 16mm images. Well none of mine would be accepted by Alamy but the 18-55 ones would definitely sail through. We will see what transpires.

I think it is easy to get used to the menu options. I used A and found the same problem as David Kilpatrick. I turned the control wheel and changed the A to S relationship without realising it. Now more careful about how to handle the camera. Need my varifocals to read the settings on the screen. Not exactly a pocked camera with the 18-55 but camera with both lenses fit into a small Hama bag and the combo is lightweight.

[alphaomega]

Just posted this on the Sony Ultra wide conversion lens VCL-ECU1 - Any users? post

In any event I have now got back my 16mm pancake lens repaired. Sony replaced a part entiled "Block,servie - Defect Code A1-Misoperating". I must confess I am none the wiser, but the lens does perform better. Tried in dull weather, but looking for sunshine for a better test. Still not very good at F2.8, but that appears to be common to the beast. Tried on my VCL-ECU1 and it would appear that at 100% there is no reduction in IQ compared with shots W/O the converter. So Sony in Thailand have QC cleared a lens with a defective part. I have seen identical descriptions of my original problem on DPReview so the problem is not restricted to me. My guess is that it is known within Sony as they can turn round a lens in five days. Happy times.

So the simple answer is that if you have a sub standard 16mm pancake E lens it is worth sending it to Sony for a repair.

[sparaxis]

I bought the two lens kit around the holidays and I found the 16mm lens to be better than many give it credit for. So a good one is worth finding.

If one looks at many reviews of the fabulous Zeiss 24-70 it appears to have fairly poor corners at 24mm and F2.8. So for the $100 I paid the 16mm is fine.

I compared it to a few other lenses I have.

16mm at f2.8:
Centre quite sharp, three corners a bit soft, RH bottom corner a bit blurry.
Note that these are the CORNERS. By the far-edges (i.e 12mm from the center) the image is fine for a lens at full aperture. Stopped down to f5.6-f8 I have no complaints. Remember that if you crop for "normal" print proportions (8x10, 12x16) you tend to crop the bad corners off anyway.

24mm Minolta at f2.8 on A850.
In a nutshell, much worse corners than the 16mm
(relatively speaking of course)

25mm F4.0 Skopar at f4.0
About the same as the 3 best corners, but more vignetting.
(16mm at 4.0 is much better!)

28mm f1.9 Ultron at f1.9
Center sharper, corners a little worse. By F2.8 the Ultron is better.

All in all, a very usable little lens.

Alan

[alphaomega]

Thanks for your comments Alan. You were lucky to get a good copy first time of the 16mm pancake. Looking at DPreview and my own experience it would appear that getting a good copy may be "the luck of the draw". The fact that Sony UK could fix my lens in a few days and had the spare part tells you something. I guess that they must know that variable quality copies have been released from the Thailand plant.
My repaired lens is much better and I appreciate what you are saying. It is a compact lens with only four pieces of glass. Somebody commented on DPReview that the ultra wide converter improved on the lens. I certainly have not detected a deterioration. Maybe the addition of the three lenses in the converter actually improves on the 16mm with only four lenses. Stranger things have happened. Some day David Kilpatrick will probably have something to say about this as he is the expert.