Experimenting with the In -camera ND filter

I've just taken a series of this image at different camera settings.  This one was 10secs at ISO 100 and F22 - I need to make myself a chart.  It doesn't work outside of course, where there is much more light, so I'll need a different chart.  In fact I'm thinking that I might need a mix if in-camera ND plus an ND filter.  (For another day.)

We have a meeting of the Yorkshire Creative Group on Zoom later this afternoon with some possible changing to how it might work being put forward, so it will be interesting to see.

p.s. I've been thinking that I might put together a set of ICM images taken inside as I often do a fw test shots when I'm setting up the camera.