Mophead Hydrangea, 5:1 macro
These photos are the result of a technical stress test, so this is going to be a nerd post to welcome you to my world of pain.
We're dealing with extreme macro here (2.5 - 5x magnification) which brings unique lighting problems. When you go beyond a 1:1 "normal" macro magnification, the concept of "effective aperture" applies. A rough formula:
Effective Aperture = Lens Aperture x (1 + Magnification).
Example: f/5.6 at 5x magnification becomes 5.6 x (1 + 5.6) = f/37.
If you're familiar with aperture, you'll know f/37 means almost no light enters the lens. And this is just a mild example, in some situations you can end up with f/60, or f/80.
In more human terms, neither daylight nor your normal indoor light will be enough to even see much in the viewfinder at all. Instead, you need to take the strongest light you own and hold it directly next to the subject, almost touching it, to even see the subject.
Whilst this would allow you to position and focus, it's just the beginning of our problems. The light has to be very strong yet cold, as to not fry the subject. It needs to have consistent output, not flicker, and have a stable color temperature.
Yet by far the biggest issue is that even with such a suitable light, it's still not strong enough to be able to use a fast shutter speed. A slow shutter speed is a fatal problem with extreme macro. Higher magnifications bring problems even experienced 1:1 photographers were unaware of.
The wind flow in your house. Somebody walking the stairs. The laundry machine in the next room. A heavy car driving by. Each will destroy your photo stack, and you have to start over.
Some people counter these problems in creative ways: rubber feet, dampening plates, wind screens, the like. Others simply go for even bigger lights, because they really need a faster shutter speed. And bigger lights are not an exaggeration:
Note the additional problem of the insanely tiny working space between lens and subject. And once again, if those lights are hot, the subject itself, especially a flower, will move. It could be only 0.1mm, yet that's enough to ruin a stack.
All of the above is called a continuous light strategy. Despite its challenges, some people are successful with it, but it's very hard or requires extreme measures. The biggest upside of all this pain is that continuous light gives you direct feedback on the exposure, what the photo (or one photo in a stack) will look like.
And then there is flash. Flash is uniquely suitable to produce a large amount of light in a short time span, allowing us to freeze the subject. When we freeze the subject with a fast enough shutter speed, micro vibrations no longer matter (yet subject movement still does).
Yet here too we have problems. At a shutter speed fast enough to eliminate vibration, says 1/200s or faster, we ask the very maximum of the typical flash unit. Now consider that we're asking that 100 times in a row, just to produce a stack to combine in a single photo.
The first problem is battery life. You'll blast through 4 AA batteries in about 3-5 stacks, or at most 10 when using slower shutter speeds. Which is not very sustainable, as well as expensive. To add insult to injury, the battery can die halfway down the stack, ruining the entire stack. But before that happens, the unit will lower (or vary) output between shots, which again is fatal, as a stack needs to be consistent from beginning to end. If you have a cheaper flash unit, you may even destroy your unit this way if it does not have built-in protection against overheating.
(continued in comment below...)
''Hydrangea macrophylla'' is a species of flowering plant in the family Hydrangeaceae, native to Japan. It is a deciduous shrub growing to 2 m tall by 2.5 m broad with large heads of pink or blue flowers in summer and autumn. Common names include bigleaf hydrangea, French hydrangea, lacecap hydrangea, mophead hydrangea, penny mac and hortensia.