My test subject was a small (50mm high) candle holder and my living room. The composition was that I wanted to place the candle holder as close to my (EOSM) camera as I could: about 15cm away.
I wanted everything from the candle holder to infinity to be tack sharp and that my infinity blur was to be optimized to the best possible, ie better than the hyperfocal and finish with an infinity defocus blur of just over the sensor limit of my EOSM.
I first used the ML auto ETTR at ISO100 and at a focal length of 14mm, to give an exposure of 4 sec at my chosen aperture of F/7.1.
Having placed my focus at the macro end of the lens, ie at a reported 15cm, the Focus Bar script told me the minimum number of focus brackets would be eight, ie at an overlap blur of the defocus blur. However, as I wanted a high quality focus stack, and was aiming at an overlap blur of around 10 microns, I knew I would be taking more that eight brackets.
Once I had taken the first bracket and started focusing towards infinity, the Focus Bar provided me all information I needed when deciding the next focus distance. Once I saw around a 10 micron overlap, I took anther image, and repeated this until I entered the infinity focusing zone and finished my focus bracketing sequence at around an infinity blur of about 10 microns. In all I needed 12 focus brackets and all, thanks the Focus Bar, were optimised for their image to image overlap.
Next the 12 images were ingested into Lightroom and the first image minimally adjusted and the other 11 synced to this base image. Here are the first and twelfth images:
From within LR I then exported the 12 images to Helicon Focus and let it do its magic, before seamlessly returning to LR with the merged image. After a little bit of perspective tweaking, and minimal exposure tweaking, I ended up with this image:
I hope this simple demonstration has helped Canon Magic Lantern users, interested in focus stacking, take a look at my Focus Bar.