Have done another test, this time of a floral display. Taken with 35mm f2 prime, electronic shutter, 20 images, step 6, 0 interval so only a few secs to take all images. The display is about 2ft top to bottom and 18 inches front to furthest visible at top. On inspecting the 20 images only 6 covered the focus range, so I put these in Helicon Focus and this is the result (albeit with a little contrast and clarity adjustment in LR on the Velvia simulation JPEG and then down sizing for LULA). Guess that I need some estimation in each case, but better to take more than necessary and then select for stacking to one image. I'm happy so far.
I'm not doing anything in firmware v4.0 to cause problems so carrying on using it till next update.
Best wishes.