Now all I have to do is work out how to turn off the acceleration.
DAPMacro Hopefully, you found how to turn Acceleration OFF. If not, it is in Settings > Performance. You'll probably need to restart Affinity.
I'm a bit curious as to your procedure. I've done some focus merging and haven't found it necessary to do what you are doing in Step 4. I'm not criticizing your approach, but I'm not sure how it helps. Perhaps due to wind outdoors? Again, I'm just curious.
I have found that I need to maintain the same camera-to-subject angle of view when shooting. If I move the camera to the left or right, I get a different view of the subject, which I've found doesn't work well with focus merging, making it difficult or impossible for Affinity to properly align the images.
I just shot a series of 14 RAW images, handheld, using a subject that would make poor focus merging pretty obvious. My camera was set to Manual Mode, 1/160s, f8, ISO 1600. I did my best to maintain a steady camera position, but I'm sure there was movement during capture. I set the camera to continuous firing mode and adjusted my lens focus manually very slowly while shooting. This gave me a series of different focus points.
The only thing I did was set the White balance the same for all shots. (I developed the first Image from RAW, set the WB, then when focus merging, I selected "Previous Parameters", which applied this custom WB to all frames.) Then I ran the focus Merge on all 14 images. I found that Affinity aligned the images perfectly and compensated for slightly different sized images (due to focus breathing?). I didn't do any touchup from the Sources Panel. I didn't do any additional processing at all after the focus merge was complete. I exported to JPG, 85% Quality, 1600 px on the long side, and this was my result.
