The Art of Focus Stacking - Matrix Software

Introduction to Second Edition
ing, we learn to drop some of the back layers and just
have a nice bokeh.
In taking a photo, we first select a focus point; we
focus. Then, and only then, we decide on how much
depth of field we need by adjusting the aperture. Of
course, due to various light and other conditions we
don’t always have much choice in the real world. But
theoretically we do.
If we go wide-angle, we have more depth of field and if
we go telephoto we have a more narrow depth of field.
That is why with wide-angle lenses there is often little
to no bokeh because everything is too much in focus.
And with telephoto lenses we can have the subject in
exact focus against a nice blurry background – good
bokeh.
When we are close up, we tend to have a very narrow
DOF, while shooting at a distance with a narrow aperture
gives us a wider depth of field ; more of the subject
is in focus.
And while this topic is too complex to go into here in
detail, there are three factors that help to determine
your depth of field: aperture, focal length of the lens,
and distance to subject. They can be summed up in
this table.
Narrow DOF Greater DOF
Large Aperture Small Aperture
Telephoto Wide-Angle
Close-up Far Back
As you can see, we can get greater DOF by using a
small aperture, a wide angle lens, and by standing far
back. However these three factors don’t all work together
smoothly for close-up work. If we stand far back
with a wide-angle lens set to a small aperture we get a
great depth of field of whatever is at infinity but it won’t
help us in macro and close-up photography.
For close-up work we have to mix and match techniques
to get any kind of depth of field and the history
of photography is filled with attempts to push any of
these approach as far as possible, which brings us to
Focus Stacking.
Focus stacking is a non-analog (digital) approach to
taking photos with increased sharpness and the appearance
of greater depth-of-field. Actually, focus
stacking is a sampling technique similar in approach
to CDs and DVDS in that an analog (reality) source is
sampled with enough to approximate a desired result.
With CDs the desired result is music, with DVDs it is
movies, and with focus stacking it is a composite photo
with enough samples to give the impression of greater
sharpness and depth of field.
Beginning
It has been several years now since I intensively began
to work with focus stacking to achieve better all–
around focus and at least the illusion of greater depth
of field. For myself I have learned a lot about this apparently
simple but demanding technique. Focus stacking
originally arose as an in-studio technique where
bellows and incremental focusing rails were used to
take hundreds of micro-stop photos that were combined
to create a single ultra-close-up photo of something
like the compound eye of a bee or dragonfly or
whatever. Since I already spend enough time indoors,
that approach was not all that appealing to me. Also,
a couple of dozen images of various compound insect
eyes were plenty for me. I got the idea.
I was more interested in how focus stacking might
be applied to outdoor nature photography using a
much smaller series of photos and doing away with
the bellows, focusing rails, and what-not. I was not
so interested in ultra-close-ups of anything as I was
in getting a little more depth of field out of whatever I
was photographing, whether it was an insect, a flower,
plant, and so on. I wanted more of whatever I was
photographing to be in focus. I like what I call “minilandscapes,”
small worlds where everything is pristine
and… in focus. That was the intention.
I use Nikon systems and back then I happened to
have the Nikon 105mm f/2.8 macro lens and that is
where I began. Any lens can be used to stack photos,
but generally this technique excels at close-up and
macro ranges. You can stack landscape photos (and
to good effect) but of course at a distance even the
tiniest of change in the focus has a huge effect. In
other words, once you get out toward infinity the number
of the stacked photo images that are effective are
few to none. This is generally true of many wide-angle
lenses as well.
Wide–angle lenses by their nature have greater depth
of field, and turning the focus even a small amount
changes the image greatly. Although I am learning to
stack photos using wide-angle lenses, you really need
a wide-angle lens with a long focus throw to do this
easily or mount the lens on a focus rail and do it that
way. Few wide-angle lenses have a long focus throw.
In general, the focal length range of lenses that works
well for focus stacking in my experience are from
60mm to 200mm and then only if these lenses are
dedicated macro lenses. Keep in mind that there are
Nikon 105mm lenses that are not macro lenses and
that do not get close enough to smaller subjects to
make them worthwhile. So do be careful when purchasing
a lens for macro work to make sure it is a true
macro lens and not just a standard lens. Also some
lenses claim to have a macro option, but I suggest
you avoid these as well. If you love macro and closeup
photography, just get a standard macro lens.
Investment
Macro lenses can be had on the cheap, so to speak,
because in macro photography (and absolutely in
focus stacking) only manual focusing is used. Auto
focus is not needed or desired. Because most photographers
today think only in terms of auto-focus lenses,
a good Nikon 105mm f/2.8 lens can be found on Ebay
for between $200-$300. Of course you can pay a
lot more, but you can do fine macros with the Nikon
105mm macro lens or the Canon equivalent.
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