Tuesday, June 11, 2019
Macro Myths, 2019 Edition
#1 The "bug lens" myth. Some people say that long focal length lenses are best for shooting insects (a "bug lens"). That one really took me back, cause I know a lot of macro photographers that shoot active subjects with short focal length lenses (I'm one of them). In fact if you want to use a flash as the primary light source then a short focal length, in the 60mm range, is optimal. You need to get the flash as close to the subject as possible to keep the duration of the flash to a minimum, and getting the flash close also gives you better diffusion (both explained in more detail later). So you really need to learn the habits and quirks of the subjects that you want to shoot because it's your knowledge of them, and their willingness to let you get close, that will determine if you get the shot. To a skittish critter the working distance of a lens doesn't matter, so there is no such thing as a "bug lens".
#2 The focus stacking myth. Still a lot of people claiming that you have to focus stack to get enough depth for macro. But most of them are really saying that in order to get razor sharp images that have some depth you have to focus stack (and that's actually true). The kind of detail that a focus stacked image will give you is almost lost on the web and in print, and the average person doesn't care about absolute image sharpness because they're looking for something to save to their computer desktop (or their phone's screen) as wallpaper. People who don't pixel peep want images that look good edge to edge, and you don't need to focus stack to create images that have a lot of depth and detail. You do need to look for, or learn to create, magic angles (angles that make the most out of the depth in a single frame). But the myth persists because some people can't see the picture because the pixels are in the way...
#3 The diopter myth. Plenty of people saying that adding any additional glass to a lens will degrade image quality. I'd preface that statement that if you add cheap glass to a lens then you're going to see a loss of detail, and maybe a lot of other artifacts as well. But most high quality diopters (close up lenses), or even teleconverters won't have a huge impact on image quality. You have to pixel peep to notice any difference. If you need to use additional glass to get a shot then use it -it's better than no photo at all...
#4 The 100mm macro lens myth. Macro lenses in the 100mm range are not good beginner lenses. I'm guilty of this one, cause I use to recommend them for people just getting into the discipline. But the best lens for a beginner is also the best lens for someone who has some experience, and the lens you need depends on the light source. A macro lens in the 60mm range is best when a flash will be the primary light source since you need to get the flash close to the subject to keep the flash duration to a minimum (easier to freeze motion) and the closer the flash the better the diffusion. If you want to use natural light as the primary light source then get a long focal length macro lens, the longer the better. You'll need the extra working distance to keep from shading the subject, or disturbing it. Macro lenses in the 100mm range are a jack of all trades, but a master of none. Too much working distance for flash, and for natural light you'll want more room between the lens and the subject. A lot of the issues I struggled with when I first got into macro were due to using Canon's 100mm USM macro lens.
#5 The flash duration myth. The general perception that the flash will always fire fast enough to freeze motion, and as proof people will list duration times that are close to what a flash will produce when set close to minimum power. The problem with shooting macro is that there is very little surface area to reflect light back into the lens, so you'll rarely if ever be using a flash at close to its minimum setting. Compound that with motion as little as 1/4 the width of a pixel being enough to amplify diffraction, an effect I call macro motion blur. Macro motion blur won't look like traditional motion blur, but you will see a loss of detail and it's easy to blame it on diffraction alone. Although not as obvious as stopping a balloon in mid pop, or a bullet as it passes through an apple, flash based macro is a form of flash based stop motion photography. The "secret" to getting sharp images at high Fstops and magnification is to take as much control over the motion in the scene as possible (your motion and the subject), get the flash as close to the subject as possible (to keep the duration of the flash to a minimum), and use a diffuser that actually forces the light to spread out (and not just block the light). Diffraction, lens sharpness, and motion all have a very synergistic effect on each other with the end result being a loss in image detail. Unfortunately there are still a lot of people who claim that any loss of detail when shooting at high magnification and Fstops is just due to diffraction, and it's just not true.
That's my list for now. I'll add to it when and if I see more "armchair expert advice". What macro myths have you run into?