Hello again Michael and James.
I’m afraid I could not manage to achieve the ND gradient effect on the sky. I tried every which way until I was blue in the face - unfortunately I couldn't achieve the same effect with the sky.
In some way that I can’t fully repeat or understand I did manage to bring the sky down a little - it’s very very overexposed compared to the foreground, and the foreground itself is underexposed. So I did end up with both sections closer together. But I can see from the mask icon that I do not appear to be getting the correct mask effect. I’ve tried it with White and with Black and all the ways I can imagine. I went through the Affinity Beginners tutorials and some others and couldn’t find any thing useful. I found the tutorial on substituting the sky, but that’s not what I want to do. So I must be missing some important point in the whole process.
In the end I went back to my old copy of Photoshop Elements 9, found this tutorial on YouTube -
- and within a few minutes I had the ND effect. The principle seems to be very like what you both suggested, but for some reason I can’t get it working in Affinity.
I’d much prefer to be able to work all the time in Affinity Photo. So I hope Affinity add a video tutorial showing the steps needed to achieve what is a fairly basic and useful effect.
Thanks again for taking the time to help.
(Sorry, tried to include the link to the YouTube PSE 9 tutorial, but the Affinity Forum blanks it out)