Canon R5 aperture issue with EF 180mm macro

[LeonR]

I've noticed when using my Canon R5 in stills mode with an EF 180mm macro the aperture is stopping down when I point the camera at a light source (led continuous lighting). When I point the camera away from light source it opens back up. It doesn't do this with any of my other lenses. Any advice would be appreciated 

[wq9nsc]

That is normal behavior for a lens if you have the camera body in its program/automatic mode or shutter priority.  It is stepping the aperture down to account for the increased light hitting the sensor. 

If the light sources is only a small portion of the overall scene, you can change the light metering mode to cover only a small part of the sensor area (center spot, center weighted, exposure tied to focus point, etc.).  This will avoid causing the overall scene to be heavily under-exposed but it will result in blown highlights around the light.

And in general, you really don't want to be pointing the camera at intense light sources.  Lasers are the arch enemy of sensors, mirrorless bodies in particular where the sensor is always exposed when the camera is active, but other highly intense point source light emitters focused by the lens can degrade parts of the sensor.

Rodger