I am Pete, and I'll be happy to assist with your question.
This 'bloom' may be caused by dust.
In order to verify it is dust, do the following:
1) Change the iris settings - the circle should grow or shrink with the iris.
2) completely defocus - in one end of the range it will appear as a dust particle be caused by a dust blob.
You may be able to remove it by removing the dust filter on the side of the unit, and blowing compressed air over the panels.
Let me know if that works?
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