CarolT

I feel you are right, that my problem lies somewhere in there. I have always struggled with getting selection to work right. Some of the stuff last night worked and some did not, and I could not figure out why not. I *was* trying to work with the selections in Adjustment layers, I rarely if ever work with the pixels on the original image. I found that if I added a mask and worked on that. the Refine tool worked far better. It's just that somehow I thought adjustment layers had built-in masks, so I thought is would work directly. I need to go back and try to understand all the fundamentals better. Unfortunately, there is not a lot of detailed learning on AP out there; I found understanding selections far, far easier with Photoshop because of the books and online guidance that are available.
Thanks for your help! 
Carol

Check that your image is type “pixel layer”. If its a image layer, use “merge visible“ or rasterize first.
Ensure that the pixel layer is selected.
Refine works only on one single selected pixel layer. 

When rendering an image in 3d software (Modo in my case) you can render a depth map instead of adding dof in the 3d software. This is a workaround to save a lot of rendering time.
Normaly you apply the depth map in Photoshop in the lens blur filter so you can add real depth of field. In affinity I miss this option. 
 
Also in Photoshop it is possible to generate bump and normal maps. This is not a complex alchoritm. I think you can get a whole lot more users (3d market) to integrate these options in Photo. 

yes please on a plugin for On1 into Affinity Photo 
 

Thanks for the reply, R C-R! I only have a 24" monitor (it is a nice photo monitor, though), so a bit less space. I just really miss having brushes selectible from a condensed menu of some sort.
Also, unlike the dedicated painting apps I use, it seems that if you modify a brush, then select something else, the brush resets to the default. This means I need to save the brushes as a new brush, I suppose. The painting apps I use are the opposite; you modify them, they show they are modified, but stay the way you left them. If you want them back to the default, you have to reset them (which is easy of course, a button is right there).
Speaking of the painting apps, when searching the forum for info before I started a new thread, I came across a feature request for something many painting apps have, which is a right-click pop-up (or even a keyboard shortcut) that gives you a selection wheel for several recently-used brushes. I doubt we will see that, but I would love it!
Thanks again for your help!
Carol