2nd Samyang 16mm F2.0, again with problems... What is going on?

Stab

Last week I bought the Samyang 16mm F2.0. According to the reviews it is an excellent lens and super sharp at f2.0 throughout the whole frame, except for the far edges. 1 review even says that only the 'last pixels in the corners' are soft at F2.0. Well, my lens was nothing like that. It its more like the last hundreds of pixels were soft. On top of that, the left side of the screen was much softer than the right side.

I sent it back to the shop and got a new copy today. Went out to do some tests and... Well, the difference between the left side and the right side is improved (not 100%), but its still extremely soft towards the corners of the frame on all sides. Not even that far out of the center... At f8 these problems are pretty much gone, and very much usable at f4 - 5.6, but that's not what I paid this money for... The reviews clearly said sharp at F2.0 throughout the frame.

Well, I might be stupid or crazy, so I want to ask your opinion. The front element of the lens is 'rounded' and that's exactly how the 'sharp plane' looks like in my test shots. Like there is a 'circle of sharpness' in the middle of the screen.

Note that I use the Panasonic GH3 with an adapter (have tried 2 adapters btw). The lens has a Nikon mount. This shouldn't affect this problem, right? Take a look af the softness on the right and especially left sides.

http://1.static.img-dpreview.com/files/p/TS1600x1600~forums%2F52429312%2F1718a517c91a48808bde4047ef4a0952

http://2.static.img-dpreview.com/files/p/TS1600x1600~forums%2F52429312%2F9603235538114935b4c28a857767985e

http://4.static.img-dpreview.com/files/p/TS1600x1600~forums%2F52429312%2F27ac8a7ec59947fb918b584a2a6b8c12

http://2.static.img-dpreview.com/files/p/TS1600x1600~forums%2F52429312%2F426f4bda6ee1415f9c828d2853595359

http://3.static.img-dpreview.com/files/p/TS1600x1600~forums%2F52429312%2Fa166514a2e0e4284890b69d82b68ce11

All pics are shot at large apertures (f2.0 - f2.2) except for the last one, which was stopped down to f5.6 to correct the problem to show the difference. Did i get a faulty lens twice? Are the reviews false? Does this lens not work with an adapter? Camera's fault? Or is it just 'normal'?

Hope to hear your opinion. Thank you so much.

_OZ

Check it on a nikon, mounted natively.

Stab

Yea will try to find someone to test tomorrow. But could it really be the adapter? It's an aps-c lens that's mounted on a m4/3 sensor. That should even make it sharper, as it's not using the softer edges of the lens, not?

scotchtape

The lensrental blog stated that they couldn't really test lens sharpness when using adapters, even expensive ones - they did but all the graphs were horrible, even for the "best" adapters.

http://www.lensrentals.com/blog/2013/09/there-is-no-free-lunch-episode-763-lens-adapters

I have used OM glass on Canon cameras and they all seemed to be "fine" and acceptably sharp. I used a Rokinon 85mm Nikon mount on my Canon cameras and it works well as well, although the contrast is really low for some reason.

Definitely check the lens, you may have gotten 2 bad copies in a row.

vicharris

II haven't seen that problem with my Nikon mount version. I'm using a Novaflex adapter though. It beat out both my SLR 12mm and Tokina 11-16. I posted some test results somewhere on here. You probably should have posted this in the thread dedicated to this lens instead of starting a new thread as well. It's easier to find people with the lens and work through possible problems that way and keeps the clutter down on the site.

Vitaliy_Kiselev

Yep. use http://www.personal-view.com/talks/discussion/7082/16mm-samyang-f2-or-t2.2-lens/p1

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