TomD brought up a lot of good points about the limitations and vagaries of focus stacking so I tried to get a better handle on the mechanics of the settings used.
And when in need of a handy dandy close up subject I hauled out my extremely dead tarantula spider. He has the benefit of being a rather large macro subject. So I arranged the camera on a tripod at the minimum focal distance and set the bracket spacing to 4 out of 10 and selected 125 frames. After the end I measured the length of the spider that was in focus in the bracket. It came to about 2.5 inches. Now this is a ballpark because there was an angle to the camera. but this gives a decent idea of how many shots are needed to cover a depth of field.
Here is the first bracket frame
Here’s the last (125th) frame
Here is the stacked composite
And finally here is a photo taken from the same distance at a very small aperture (f\18) as a comparison.
Now this stack took 50 minutes to crank out on my laptop. Is it worth the time and effort? I guess that’s a personal choice. But I’m kind of enjoying playing around with a new technique. And that’s probably the nerd in me showing through.
Update:
TomD commented:
As a lifelong certified arachnophobe, 2.5” inches is entirely too big (by at least an order of magnitude) for a live spider to be.
Thanks for the experiment! Enlightening!
Even with 4 steps/per frame x 125 frames, or 500 steps, it still didn’t get the abdomen. So 500 steps only covered around 1.75”?
That’s extremely unintuitive and approaching unusable.
As I said in an earlier post, the software that I played with at the camera club would have the entire object with 8-10 exposures.
Maybe that’s more a function of the lens than the software. I’ve done a lot of macro work using several lenses and noticed that macro lenses with a very close focus all have a razor thin usable depth of field. I wonder what would happen if you took a good prime lens in the 85+mm range, moved it back and tried the same experiment at something like f8?
You would have to crop in to get the same image size but I’ve noticed that ou A7IV’s can be cropped quite a ways and still have great IQ’s (image quality).
Using the setup specs of your experiment, I’d say that the upper dof limit is in the inch range.
photog replied:
Tom, I’m going to play around with this function. I want to see what I can do with it. It seems like an interesting tool that I might find some good applications for. But I can see that it might not have any compelling uses for most people.
