Vignette problem

[jedam]

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Am 26.12.2015 um 19:47 schrieb Likaleica:

Running backwards, Drive on continuous medium, Shutter speed priority.  24/90 at 24.  Some frames show vignetting, others don't.  

 

Thoughts?

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Recently I found same on a 24-90. Directly in LiveView and on taken pictures. Just at 24, going away when slightly zoomed in towards 35. Including weird pillow. This told me somehow the focal length was not grabbed correct. I cross checked this with a second camera and different lens that the 24-90 was the culprit. You can see mm focal length in preview and playmode when Info is turned on. Ok. As the lens is out of warranty, I gave it a try. I decided to open it (warning: there are good chances to damage it, so I think it is also a good idea to send it to CS) and I found a slider contact on a resistance tray being damaged and not having contact anymore. This also explained some scratchy noises on zooming. (btw: after carrying the lens on a bicycle trip I found the lens having issues with locked zoom: the turning wheel stucked, but you could press/pull still on the front lens (not on the glass  ) - this was caused by 3 loosened screws on the outer shell. To get there, you need to disassemble the focus ring also. To get to the resistance slider it’s one less, just to the focal ring.) - What can I say: fixing the screws let’s it zoom like on day one. And the mm are back almost correct (24-85 shown going the 24-90), as I did not had a new slider, but had to unfold the ‚Knäuel‘). Again: I can not motivate you to open your lens by yourself. At least what I found there was no chance to get it optical out of sync, but there are some cables that could be damaged. You need to know how they can be unlocked  with this little fixing clip. Last note: the most tricky cable you find right after the entry, on the bajonette ring and the first seal. This was my first Leica gear surgery, and so far the only one beside fixing the M focus adjustment if is clear it‘s the camera and not the lens. All other issues I send it to the CS.

Edited February 5, 2021 by jedam

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[Eclectic Man]

The vignetting looks to be very marked.  Normally vignetting is due to the angle through which light passes through the aperture, as front-on the aperture is circular.  The further from the centre of the image circle, the more the aperture appears to be an ellipse, which has a smaller area than the circle.  Extreme wide angle lenses such as those for the GX617 camera could be amended with a centre graduated ND filter to reduce light form the centre of the field of view to enable more even exposure.

See:  https://photographylife.com/what-is-vignetting for a more detailed discussion.

"Depending on the type and cause of vignetting, it can be gradual or abrupt. There are a number of causes of optical vignetting – it can naturally occur in all lenses, or can be caused or increased/intensified due to use of external tools such as filters, filter holders and lens hoods. In this article, I will talk about each type of vignetting and also discuss ways to reduce or increase the amount of vignetting in photographs using post-processing software like Lightroom and Photoshop."

It looks more like what Thighslapper suggested, that the extreme corners of the frame are obstructed somehow.

However, nice family pics in the snow, what is the dog called?

[Likaleica]

Thanks.  Dog's name is Cody.  Was.

Turned out to be one of the defective motors in the lens.  Shortly after this the lens froze and went back to the mother ship for a new motor.  No problems since then.