Circular Issues With Canon RF 15-35mm 2.8 taken on Canon R5

[CK0]

Hello!

I have had issues with this little circle appearing in my photos for my Canon 15-35 while taking long exposures. I can't seem to find the issue.

I am not sure if it is due to some correction if it is due to some ibis issue or maybe its the camera/lens itself. Anyway, I do have my high iso noise reduction mode on but also figured if I asked on here it would be best. 

Here is the sample photos.

Thank you!

Issues in the middle with circular pattern

[rs-eos · Accepted solution]

That appears to be an interferance pattern.  Perhaps "Newton's rings".

Were these taken when on a tripod and lens IS and/or IBIS engaged? Though I don't know if that would lead to this.

[CK0]

It might be due to the lens filter I have on top. I do have ibis on one photo and have ibis off on another.

CK0

[rs-eos]

Ah, did not think to ask about an filters.  That could also perhaps lead to the issue.  What type of filter were you using? Variable-ND perhaps?

[jrhoffman75]

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@CK0 wrote:

It might be due to the lens filter I have on top. I do have ibis on one photo and have ibis off on another.

CK0

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[justadude]

I usually keep a UV filter on my lenses, but I always take them off for long exposure shots, especially at night.  Sometimes I get very faint reflections between the lens and the filter from any light source, including reflected moonlight... especially on the less expensive filters.