Photography, like any other art, demands both compelling content and expert technique to create a pleasing result. In my previous article, I discussed some of the aesthetic choices involved in creating a successful macro image. Technique, however, is an absolute must; it's the artist's tool to convey his artistic vision.
Nature, landscape and wildlife are some of the most technically challenging fields of photography, and macro photography comes with its own unique set of technical considerations. In this article I'll be discussing one of the most important ones; magnification.
|Photographer Allon Kira making sure his image is technically perfect.
For macro photographers this often requires a great deal of
concentration and patience, but the results are well worth it.
Some of the greatest challenges in macro photography arise from the simple fact that we shoot from very close distances. Thus the magnification of our subject becomes of primary importance. The magnification ability of a given lens is stated in its specifications but in my experience, few photographers understand the meaning and implications of this designation.
To understand the concept of magnification, it's worth taking a very brief look at how a photographic image is created. Every point in a given scene reflects light rays. The front element of the camera lens 'captures' these rays and then focuses them onto the imaging sensor, producing a projection of the scene at the location of the sensor.
|This is a simplified diagram of the photographic process. Light rays reflected from an object pass through a lens, which then produces an image projection on the camera's sensor.|
Magnification - or more precisely, the magnification ratio - is simply the relationship between of the size of the (in-focus) subject's projection on the imaging sensor and the subject's size in reality. Perplexed? Here are some examples. Suppose that we're photographing a small child, 1 meter in height. Imagine that the height of the child's projection onto the sensor is 1cm. The magnification ratio is 1cm/100cm, or 1/100. Magnification is typically notated using a colon, so we write it as 1:100, and pronounce it, 'one to one hundred', meaning the child is 100 times larger in real life than its image as projected on the sensor. Similarly, if the subject is a 10cm long lizard, and its projection on the sensor is 2cm long, the magnification ratio is 2cm/10cm or 1:5. The lizard is five times larger in real life than its projection on the sensor.
When your subject(s) fills the frame with no cropping involved, it is easy to determine the magnification ratio from a captured image provided you know the size of your subject and the dimensions of your camera's sensor, which can be found in the specifications section of the user manual.
We've seen in the examples above that sensor size can be used to calculate magnification, but the degree of magnification itself depends on focal length and subject distance exclusively (assuming that the lens is not used with any extenders or magnifying filters). Sensor size does not alter magnification. With a fixed focal length and subject distance, an APS-C sensor, for example would just crop the frame compared to a full-frame sensor, not enlarge it. Magnification is a property of the projection, regardless of the size of sensor (or film format) you are using. With a full frame sensor you'd just make calculations using 35mm as the sensor width instead of 22mm, but the subject would then be proportionally larger, cancelling out the sensor size difference.
Sensor size does have an effect on the image's appearance though, a topic I will address in an upcoming article.
What happens if the subject is the same size in real life as its projection? If we shoot a 1cm fly and its projection on the sensor measures 1cm as well, the magnification is 1:1. The 1:1 ratio has an important meaning for macro enthusiasts. Technically speaking, macro photography means shooting at a magnification ratio of at least 1:1. Therefore, a 'true' macro lens has the ability to produce a magnification ratio of 1:1, or higher.
|A small subject like this shield bug required approximately a 1:1 magnification.|
At this point you may understandably ask, what's so special about a macro lens? Surely one can take any old 50mm f/1.8 lens and just move it closer to your subject until you reach 1:1 magnification. The problem, however, is that a regular lens will not be able to focus at such close distances. A more specific definition of a macro lens, then, is one whose minimal focus distance is short enough to allow photography of a focused subject in 1:1 magnification.
Let me take this opportunity to point out that many lens makers employ a very liberal use of the term, and happily write 'macro' on a variety of zoom and prime lenses that are not capable of 1:1 magnifications. This is a sales tactic, and you can easily find so-called macro lenses that can only produce 1:4 or 1:3 magnification ratios. One can, of course, produce great results with such lenses, and it is often possible to achieve higher magnifications on these lenses with the use of optional accessories. When shopping for a macro lens, however, you'll want to look carefully at the magnification specs; most 'true' macro lenses will actually have 'macro 1:1' prominently displayed on the barrel. That removes any ambiguity.
Once you have a macro lens, how do you accurately calculate its level of magnification at an arbitrary focus distance? The easiest way, by far, is to use a ruler, as shown in the examples below.
I should point out that with a regular macro lens, 1:1 magnification is achievable only at the very closest focus distance. Using a longer focus distance necessarily means the magnification will be lower. Indeed, for a fixed focal length, magnification is inversely related to subject distance. This relationship isn't linear, i.e. if I get a 1:4 magnification from a shooting distance of 40 cm, I won't necessarily get a magnification of 1:2 (twice that) from a shooting distance of 20cm. However, getting closer will always result in a larger magnification and vice versa, meaning that for our purposes we can use the terms magnification and proximity somewhat interchangeably.
|Some subjects are so tiny they need extreme magnifications. This close-up
portrait of a robber fly required a whopping 4:1 magnification ratio, meaning
that the image projected on my camera's sensor was 4x larger than the fly itself.
There are cases (such as the image above) where we wish to shoot at magnifications greater than 1:1. These so-called 'extreme-macro' magnifications are possible using special lenses or other equipment, and I'll discuss how that's done in a future article.
For further reading on macro photography take a look at Erez's previous articles in this series:
Erez Marom is a nature photographer based in Israel and a regular contributor to Composition magazine. You can see more of his work at www.erezmarom.com and follow him on his Facebook page and deviantArt gallery.
Nov 10, 2014
Oct 1, 2014
Aug 10, 2014
Aug 3, 2014
|2014_1211_140657AA by old shutter bugger|
from The Bride
|Overloaded by NZ Scott|
from Your City - Delivery Boy
|Barley by Will B Milner|
|APPLE & ROACH by TX Photo Doc|
from Delicious - Unpalatable
Try your hand at this blind portrait shootout between the Canon 1DX Mark II, Nikon D5 and Sony a9. With all bias removed, you might just rank your favorite camera brand worst.
Photo sharing site 500px has just added support for wide-gamut color profiles such as AdobeRGB and ProPhotoRGB, even allowing users to filter their searches by color profile.
DJI just released a mandatory firmware update for the DJI Spark. If you own a Spark and don't update your firmware by September 1st, DJI will remotely ground your drone.
Affordable flash manufacturer Godox has updated its smartphone app so that it can be used to control all of its wireless X flash units, not just the A1 smartphone flash.
Western Digital's new My Book Duo external desktop storage system offers up to 20TB of storage capacity, and comes with RAID-optimized WD Red hard drives.
Version 1.04 of the Sony a6500 firmware can be downloaded from the Sony Support website now.
Not sure how to choose your first drone? In this article, the second of a 3-part series, we discuss what factors you should consider when deciding what drone is right for you.
NASA photo editor Joel Kowsky didn't just capture the solar eclipse from his vantage point in Wyoming, he also managed to capture the ISS buzzing across what remained of the sun.
In these videos, talented photographer and filmmaker Daniel DeArco breaks down several tips that will help flash photography newbies start experimenting with artificial light.
Photographer and master potter Steve Irvine makes incredibly intricate, functional ceramic pinhole cameras that look like robots and monsters.
Chinese gimbal manufacturer Gudsen has released a firmware update for its Moza Air that lets you control the direction and angle of the head remotely just by moving a small handlebar-mounted control unit.
Curious how the Sony a9 performs underwater? Our friends at Backscatter took the camera diving off the Baja California coast, to find out how it handled shooting great white sharks.
While most of the DPReview crew put away our cameras and just watched the celestial event, Rishi decided last-minute to hack together a rig and capture a few shots.
Defunct Russian camera maker Zenit is making a comeback, and they're planning to release a full-frame mirrorless camera in 2018.
The days where you're more or less locked into premium or first-party flash units has gone. They're less than $50 now, so there's one less excuse not to get one. Here's our case for adding one to your kit, and a few pointers to get you going.
If you're shooting the solar eclipse here's a hint: don't fry your camera's sensor. Use a proper solar filter that offers at least 16 stops of light filtration, along with UV and IR filtering. More important? Don't look at it unless you've got solar filters. Sensors can be replaced, your retinas can't.
Photographer Rick Wenner recently captured an odd event called the Race of the Gentlemen with a rather odd camera: The Phase One XF IQ3 Achromatic, the world's only 101MP black-and-white digital back.
Buying used is a good way to save some dough, and with the right precautions you can protect yourself from falling victim to a scam.
This two-part video series takes a deep dive into the world of dynamic symmetry and geometric composition, using iconic photographer Henri Cartier-Bresson's brilliant photographs as a guide.
Award-winning photographer Jeremy Cowart tells the moving story behind this drone photograph, captured in the aftermath of the devastating wildfire in Gatlinburg, TN in 2016.
Happy 2017 World Photo Day! We asked everyone on staff at DPReview to share one photo that they took within the last year that makes them jazzed on photography. Here's what we chose.
French President Emmanuel Macron has lodged a legal complaint against a paparazzo who snuck onto the president's private vacation property to take pictures.
Ever wonder what the difference is between compressed, uncompressed and lossless compressed Raw files? Photography Life's Nasim Mansurov breaks it down for you in this informative article.
The oldest known portrait of a US president was just discovered after over a century in storage. It's going up for auction in October, where it's expected to fetch between $150,000 and $250,000.
If you're using the popular Sigma 24-70mm F2.8 Art lens with Sigma's MC-11 converter, listen up: you'll want to update your lens and converter firmware ASAP.
If you've heard it once, you've probably heard it a thousand times: never check in your camera gear when flying. This shattered $11,000 lens is what can happen when you do.
Lensrentals just did its first Cine lens comparison, pitting five top-notch 35mm primes against each other: the Zeiss CP.2 35mm T2.1, Canon CN-E 35mm T1.5, Sigma 35mm T1.5 FF, Rokinon Xeen 35mm T1.5 and Schneider Xenon 35mm T2.1.
A team of Google researchers have found that slightly warping watermarks when embedding them into images can help prevent automatic removal.
You don't have to empty your savings account to take your photography to the next level. These cheap buys cost about $50 or less, and come with outsized benefits for your photography.
Joey L, Dani Diamond, Brandon Woelfel and Jessica Kobeissi go head-to-head in an episode of "4 photographers shoot the same model."