Understanding the physics of macro photography
Many photographers, from beginners to professionals, find macro photography challenging. Unlike other photographic disciplines, macro photography requires a different approach. Autofocus and the constant pursuit of ultra-shallow depth of field take a back seat. Instead, the physics of photographing up close introduces a new set of challenges. The good news is that these challenges are entirely manageable. In this guide, we will walk through the key settings and techniques you need to capture sharp, detailed macro images.
Understanding the Basics
The fundamentals of photography still apply, but not in quite the same way. ISO, aperture, and shutter speed all play a role, though some are more important than others in macro work. Before diving into specific settings, it helps to understand the technical challenges unique to shooting at close distances.
The Light Challenge in Macro Photography
One of the biggest challenges in macro photography is also one of its biggest advantages: limited light. When focusing very close to your subject, your lens naturally allows less light to reach the sensor.
Think about photographing a wide landscape. The scene is flooded with light from all directions. Now compare that to photographing an ant within that same scene. Only a tiny fraction of light is actually hitting your subject. This makes proper lighting the first major hurdle in macro photography.
You could increase ISO or slow down your shutter speed, but that quickly introduces noise and motion blur. Neither is desirable when aiming for crisp macro images. And aperture? It introduces another challenge entirely. But being close up to your subject does bring one interesting advantage, one we’ll discuss in detail a bit later in this workshop.
Depth of Field and Aperture
The second major hurdle in macro photography is depth of field. In genres like portrait photography, photographers often aim for a shallow depth of field to create soft, blurred backgrounds. Macro photography presents almost the opposite problem.
Depth of field determines how much of your subject is in focus. A smaller aperture (higher f-number) increases depth of field, while a larger aperture (lower f-number) decreases it.
At normal distances, depth of field can span several meters. At macro distances, it shrinks dramatically, often to just a few millimetres. This is why getting an entire subject in focus can be so difficult when shooting macro.
Because of this, macro photographers typically use smaller apertures to maximise depth of field. Even then, achieving full sharpness across a subject can be challenging.
Using Flash for Better Results
To overcome low light, using a speedlight is one of the most effective solutions. Speedlights are portable, powerful, and emit light in a very short burst.
For macro photography, set your speedlight to manual mode. If your flash allows it, adjust the zoom or focal length to its widest setting, such as 24mm. This spreads the light more evenly across your subject, resulting in softer illumination.
For the best results, pair your flash with a macro diffuser. This helps soften the light further and reduces harsh shadows. Being able to use a flash as your light source is the big advantage of macro photography. It gives you the power to manipulate the light in almost any situation.
Recommended Camera Settings
Once you introduce controlled lighting with a flash, you gain much more flexibility in your camera settings.
ISO
Keep your ISO as low as possible to reduce noise and maintain image quality. For most cameras, this means ISO 100. Some systems, such as OM System cameras, have a base ISO of 200. Base ISO is the setting that produces the cleanest image.
Shutter Speed
When using a flash, shutter speed becomes less critical for exposure because the flash provides most of the light. However, you must stay below your camera’s flash sync speed, which is typically around 1/200 second. A safe and practical choice is 1/100 second. Thanks to your flash firing so quickly, the shutter speed becomes somewhat irrelevant as the short burst of light will freeze your subject in action, making it safe to shoot handheld.
Aperture
Aperture is your primary tool for controlling depth of field. In macro photography, you will often need to stop down your lens significantly. However, going too far, usually beyond f/16, can introduce softness due to diffraction.
Most lenses are sharpest around f/8 to f/11, though this varies. It is worth checking lens tests to find the optimal aperture for your specific setup.
Sensor size also plays a role. Full-frame cameras produce shallower depth of field compared to APS-C, and even more so compared to Micro Four Thirds. This means you may need to use smaller apertures on full-frame systems to achieve similar depth of field.
Dialling in Your Flash
With your camera set to a low ISO, a shutter speed around 1/100 second, and an aperture near f/11 to f/13, your flash becomes the main tool for controlling exposure.
Adjust the flash power manually until your subject is properly lit. If using a ProMacro Diffuser, something like 1/16 power often works well, but this will vary depending on your distance to the subject. The further you are from your subject, the more light you will need.
