Vignetting - do I need larger filters?

[Gina]

Very good point Olly

[Jonk]

10 hours ago, ollypenrice said:

You do have quite a bite out of the top right corner, though, and this could be filter wheel positioning.

That's right, which I think I mentioned somewhere before. In fact, that's all it can be. The wheel senses the filter position using what looks like photodiodes, so I'm wondering if the position can be calibrated.

PI can measure the fall off of a flat and of course the images above are autostretched to demonstrate this.

Since I asked the original question, I'm happy now that it's all ok as it appears to calibrate absolutely fine.

All part of the learning curve!