Sigma 20mm DG DN sudden issue at f/1.4

[jiggyb21]

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Hi everyone.  I have a Sigma 20mm DG DN for my Leica SL3 and SL3-s and I have been shooting astro with this lens for years.  I have definitely shot many a photo at f/1.4 and never noticed an issue.  I decided to run a comprehensive test on all my lenses to see which performed best at certain focal lengths and aperture, just to learn a little more about my equipment.  It is expected that the Sigma will sharpen as you close the aperture down but check out these images.  There is a very weird haze/glow at the point of focus.  I think there is something wrong with the lens because, as I said, I've never noticed this before.  

 

The first photo is f/1.4 and f/2.0 (also noticed how dark the 1.4 frame is...almost like it's vignetting the entire frame.   

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The second photo is f/2.8 and f/4 (sharpens up a lot obviously)

 

Do I send the lens to Sigma?

 

[jaapv]

Focus appears to be on the bucket under the shed.

[jdlaing]

Shutter speed is responsible for the dark image.

[jankap]

10 hours ago, jdlaing said:

Shutter speed is responsible for the dark image.

1/3200 at f/1.4 -- 1/1600 at f/2 -- 1/800 at f/2.8 -- 1/400 at f/4 >>🤨

Edited April 20 by jankap

[jiggyb21]

Here are four more examples but this time of a flat subject.  Manually focused on the brick.  Same results.  Less obvious, but still darker overall at f/1.4 than the others and notice the halo effect around the wires.  

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[jankap]

Could you test the lens at infinity? Perhaps this lens has an advantage for astronomy projects.

I found this review. Positive results.

https://www.cameralabs.com/sigma-20mm-f1-4-dg-dn-art-review/

 

Edited April 21 by jankap

[jiggyb21]

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A follow-up for anyone who’s curious or to those who find this thread later. I sent the lens to Sigma and they said the lens was indeed in need of repair. I was quoted $315 for “replacement of fixed barrel 1 unit”

 

From what I understand that is the very front ring that filters screw into and what holds the fixed outermost element in place. That’s all pretty odd to me because I’m pretty careful with my gear but I do go out in all weather conditions. We’ll see. 

[jiggyb21]

A follow-up for anyone who’s curious or to those who find this thread later. I sent the lens to Sigma and they said the lens was indeed in need of repair. I was quoted $315 for “replacement of fixed barrel 1 unit”

 

From what I understand that is the very front ring that filters screw into and what holds the fixed outermost element in place. That’s all pretty odd to me because I’m pretty careful with my gear but I do go out in all weather conditions. We’ll see. 

[Babylonia]

Okay. Unfortunately a repair issue for correction.
But good to know what could be of importance which parts are sensitive for miss alignment / defect.