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Sony FE 35mm f/1.4 Distagon: Quality Control Issues, Right Side Blur at f/1.4

Get Sony FE 35mm f/1.4 Distagon at B&H Photo.

Sony FE 35mm f/1.4 Distagon ZA

See my review of the Sony FE 35mm f/1.4 Distagon ZA in Guide to Mirrorless.

When Sony released the FE 35mm f/2.8 Sonnar and 55mm f/1.8 ZA Sonnar for the A7 series, there were various reports of quality control issues, some I read of and some reported to me by readers. Such things are rather common with most brands.

I am disappointed to report that after shooting the new FE 35mm f/1.4 Distagon extensively on many different scenes this evening, one consistent issue emerged with the test sample in every scene I shot: at f/1.4, the lens could not make a sharp image on the right 1/3 of the frame, even as the center and left sides delivered the quality that so impressed me with my original portrait shoot. Stopping down, the issue cleans up nicely, but clearly this sample has something amiss. My feeling on this verges on anger, since my images cannot be fixed, and quality control this shitty at this price is an insult to the buying public. The factory could catch problem lenses like this, but it did not. Still, I will be showing several series, because the core lens qualities are visible over most of the frame at f/1.4, and because the issue itself has to be seen to be understood, and because stopped down there is a lot to like.

My advice to anyone remains as usual with any brand: don’t assume the sample is good; examine a variety of scenes for consistent issues, like blur on one side and not the other. See How to Test a Lens in Making Sharp Images. One reason I like the Zeiss ZF.2 / ZE DSLR lenses and particularly the Otus line is that over the years I’ve had hardly any issues—the best quality control of all the brands IMO. A lens design is only as good as it can be built, one reason why computed MTF charts supplied by most vendors are a joke.

Update: I’ve published a series showing how much stopping down is needed to overcome the right-side blur in this bad lens sample as well as a variety of samples. See also Lens Shock Testing.

f1.4 @ 1/4 sec, ISO 80; 2015-04-17 19:09:23
Sony A7R + Sony FE 35mm f/1.4 ZA

[low-res image for bot]

Peter G writes:

I knew something was up with my 35mm 1.4 ZA wide open, it was almost as though there was no in focus area in certain shots. Well, your article made me specifically test the right side of the lens against the left and sure enough I have the same problem you are talking about. Attached are two 100% crop images demonstrating it.

On the right side, I can see the fringing converge from purple to green with ALMOST NO in focus area once it reaches the in focus zone.

Now I need to run it back to Sony and hope that a proper replacement can be offered. Luckily I purchased it from our local Sony store directly. Did you successfully get your lens replaced?

Thanks for your article, it amazed me how well you were able to isolate the problem!

...

I just finished testing the other two samples in the Sony store and they both had the same issue. I've asked them to contact their product team to see if they can procure a good sample (if such a thing exists at all). In store I was testing with a different camera. I have a feeling there could at the very least be a bad batch of lenses!

DIGLLOYD: I never purchased the lens; it was on loan, so it went back. It’s tough getting symmetry on high-res digital particularly f/1.4 lenses. It’s one thing that makes the Zeiss Otus lenses stand out: world class quality control. But one cannot assume that the lens is at fault without testing multiple lenses and at least two camera bodies, because tolerances can combine with a particular body and lens. And lens mounts can be non plane-parallel with even 10-20 microns visible as an asymmetry.

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