Transforming Ordinary Lenses into Super-Macro Lenses 🙂
Friendly suggestion: this is not a quick-read. This is Part 1 of a 3-part series on “beyond 1:1” macro photography. As such, this article is best read from a full-sized PC or Mac, or maybe a laptop (when you have some time to concentrate and can really look at the images) … rather than your cell phone. With that said, this article describes one of many ways (imo, the best way) to shoot beyond 1:1 macro of living subjects. (There are better methods to shooting dead arthropods, but this article deals with shooting live subjects, beyond 1:1.)
With that said, realize that shooting “1:1 macro photography” means you are photographing a 36mm subject and transposing all 36mm of your subject onto your full-frame (36mm) sensor. In other words, you will “fill the (36mm) sensor” with that 36mm subject. The image reproduction ratio, relative to the sensor, is therefore 1:1 (or 1x lifesize) at the lens’ closest focus distance.
Rubbing your chin on this fact, the reader will note that almost all commercial macro lenses are advertised as 1:1 macro lenses. However, some macro lenses only offer a 1:2 reproduction ratio … this means a 72mm subject will fill a 36mm sensor at the lens’ closest focus distance. This is called “half life-size” magnification, but it is still a greater reproduction ratio than standard lenses offer. (I.e., standard lenses only offer 1:6 to 1:10 maximum reproduction ratios). In other words, at 1:10 (or 1/10th lifesize), a subject 10x the size of a 36mm sensor (360mm) will be reduced to “filling the frame” of a 36mm sensor at its closest-focusing distance. Thus most lenses shrink the subject, even at their closest-focusing distance. By allowing a 1:1 reproduction ratio, true macro lenses enable photographers reproduce tiny subjects 6-10x closer than standard lenses, thus enabling the macro shooter to reveal subtle details of tiny subjects far beyond what ordinary lenses can do. Although this ability sounds like a photographic Nirvana, the trouble is, as wonderful as 1:1 (and even 1:2) macro lenses are, there are many interesting subjects that are much smaller than 36mm in size. This means, in order to adequately photograph such subjects in detail, we need a lens that enlarges tiny subjects to “fill the frame” of a 36mm sensor.
For example, the crab spider up at the top of this page only has a 4mm body and a 7mm total leg span. She would fit completely on your pinky-fingernail. She is far too small to capture, in this much detail, using even a standard 1:1 macro lens. So the question thus becomes, “How do we capture an image like this using standard macro equipment?” The simple answer is, you can’t. To get as close as I could, and leave just a little space around her legspan, I needed to enlarge approximately 9mm of subject onto a 36mm sensor. Remember, the best a standard macro lens could do would be reproduce 36mm of subject onto a 36mm sensor (or get ¼ this close), and I would have lost critical detail trying to ‘crop’ the image at that low of a magnification. Therefore, in order to get as much detail as I did, I had to go in 4:1, four-times as close as a standard macro allows, which means I had to ‘fill a 36mm sensor’ with 9mm of subject (to give a little room around the spider’s 7mm legspan). The technique and tools required to go about this brings us to the topic of this blog entry: Professional-Level, Reverse-Lens Macro Photography.
Reverse-lens macro photography is the act of taking a standard prime (or zoom) lens, and reversing it, connecting the filter threads of the front element to the camera (via an adapter) and leaving the rear element protruding outward toward the subject. The goal in doing this is to achieve extreme magnification, inversely-proportional to the width (focal length) of the lens. That is, the wider the lens is, properly-oriented, the closer it focuses, when reversed. Note: a 50mm lens, “the standard,” when reversed, allows us to achieve ~1:1 magnification. For example:
- A 50mm lens reverses to ~ 1x magnification
- A 28mm lens reverses to ~ 2x magnification
- A 20mm lens reverses to ~3.4x magnification
Reversing a lens greater than 50mm is therefore pointless (less than 1:1). Lenses wider than 20mm typically have front elements too big for reversing (more detail below). Thus lenses between 20mm and 50mm are the ideal candidates for reversing.
This brings us to the subject of magnification, and trying to visualize what degree of magnification we seek. Before we proceed, keep in mind this article is being written with respect to a full-frame sensor size (36 x 24 mm). If you have a sensor-size different from this , then the magnification values will vary, with respect to your particular sensor-size, but the principles here will still apply. As mentioned above, with a full-frame sensor, when we speak of 1:1 (or 1x) magnification, what this means is when we use a standard 1:1 macro lens, at its closest-focusing distance, we will “fill our (36 x 24 mm) frame” with the subject. If we’re only at 1:2 (half-lifesize, or .05x) magnification, then we’re capturing a 72 mm subject across our 36 mm sensor. If we’re only at 1/4 lifesize (or .25x) magnification, then we’re capturing a larger 144 mm subject across our 36mm sensor. Makes sense? Good.
However, what about if we’re going in closer, rather than wider? And then, what about if we’re using a “crop” (APS-C) camera? How does these things affect what we’re doing? [Nikon “crop” sensors are 23.6 x 15.7mm (giving a 1.5x multiplier), while Canon APS-C sensors are 22.2 x 14.8mm (giving a 1.6x multiplier). In other words:
Full-Frame vs. Crop (APS-C) Sensors
I realize this is all confusing, so let’s get back to basics. Remember, a lens that gives us a full-frame reproduction is said to be 1:1, 36 x 24mm. By contrast, when we use a “super” macro lens, rather than moving away (to half-size), we are now moving-in passed the standard 1:1 macro reproduction rate, to achieve a 2:1 (or 2x lifesize) magnification level. At 2:1 (or 2x) magnification, this means we’re “filling the frame” with a mere 18 mm subject. If we move in even closer, and go to 4:1 (or 4x lifesize) magnification, now we are filling our frame with a 9mm subject, such as the tiny crab spider female up top. For this reason, “crop” (APS-C) cameras, with smaller (24 x 16mm) sensors, are often preferred for macro photography … because they offer a 1.5x magnification factor. That is, a 1:1 lens offers 36mm of frame coverage on a full-frame camera, yet it fills a ~24mm sensor on an APS-C camera. Let’s see how this plays out on a table, namely how the same lens, reversed, magnifies on a full-frame camera vs. an APS-C:
Thinking in Terms of Millimeters (mm)
(Nikkor AI-S Lenses)
(on Full Frame - FX)
(on APS-C - DX)
|A 50mm f/1.2 AI-S lens reverses to:||1.1x ( = 32.7mm edge-to-edge coverage)||1.7x ( = 21.5mm edge-to-edge coverage)|
|A 35mm f/1.4 AI-S lens reverses to:||1.8x ( = 20.0mm edge-to-edge coverage)||2.8x ( = 13.1mm edge-to-edge coverage)|
|A 28mm f/2.8 AI-S lens reverses to:||2.1x ( = 17.1mm edge-to-edge coverage)||3.2x ( = 11.2mm edge-to-edge coverage)|
|A 24mm f/12.8 AI-S lens reverses to:||2.6x ( = 13.9mm edge-to-edge coverage)||4.0x ( = 9.1mm edge-to-edge coverage)|
|A 20mm f/2.8 AI-S lens reverses to:||3.4x ( = 10.6mm edge-to-edge coverage)||5.2x ( = 6.9mm edge-to-edge coverage)|
With this paradigm in mind, based on the sensor size we’re using, when we decide what magnification (or reproduction ratio) we want to achieve, we need to take the size of our subject into consideration. Here is a visual of the difference reverse-mounting key prime lenses can make, on FF vs. APS-C cameras, compared to a standard 1:1 (1x) macro lens:
Lens Magnification Visual Comparison
This is as close as you can get to a dime w/ a standard macro lens @ 1x on a 36 x 24mm sensor. br>
Now let's see how close you can get, using key prime lenses, reversed, depending on your type of camera (FF or APS-C) 🙂
Whether we’re using a 36mm sensor, or a 24mm sensor, we need to consider our sensor measurement, balanced against the size of our subject, in order to come to terms with the degree of magnification we seek. To do this, it is helpful to visualize a metric ruler:
Using the ruler above, as well as considering the size of a dime above it, we begin to understand that a standard 1:1 macro lens will only allow us to capture a subject that fits within the green 36mm frame. This tiny area will comfortably-fit a variety of small subjects (e.g., small butterflies, most beetles, wasps, bees, etc.), while, some macro subjects might be too large to fit within the green 36mm sensor-size (larger butterflies, praying mantids, grasshoppers, snails, etc.). Therefore, for these larger subjects, backing-off to 1:2 or even 1:4 will be necessary in order to capture the entire subject on our 36mm frame.
However, sometimes we are faced with the opposite situation: we need to move in closer, passed 1:1, in order to achieve 2:1 or even 4:1 lifesize magnification—or beyond (look at ruler to see the difference). There are many small arthropods (spiders, flies, ants, aphids, even tiny flowers), for which a standard 1:1 macro magnification is simply inadequate to “fill the frame” with these diminutive subjects. Therefore, in order to move beyond the limitations of standard macro lenses, Nikon has created reversing-rings, which allow you to invert wide-prime lenses (as well as zooms), which thereby enables you to achieve magnification levels not possible with standard macro lenses. However, there are some limitations here too (to be discussed below).
With this visual in mind, above, now let us see how we can reverse lenses to go the opposite route, to get closer than 1:1, when our subjects are much smaller than a 36mm sensor. Take, for instance, a common Green Bottle Fly (Lucilia sericata), below, which is only about 6-9mm in length. How can we capture an image of this fly adequately, on a 36mm sensor, when my sensor is 4-6x bigger than the subject? The answer is we have to get closer! Using the ruler above, we can see that a 3:1 reproduction ratio will enable us to fit 12mm of subject onto our sensor. This will take the whole 9mm subject in and allow some room to see a bit of background:
So How Close Should you Go?
Now that we’ve touched on the subject of considering the different magnifications needed, to go beyond 1:1, remember that shooing macro from 1:4 (144mm subjects) to 1:1 (36mm subjects) can be accomplished with any standard macro lens … you don’t need this article for that. It’s when we move beyond 1:1, say up to 2:1 magnification (18mm subjects), all the way in to 4:1 magnification (9mm subjects), where we are going to require special equipment. Realize further that anything beyond 5:1 magnification (7.2mm reproduced to fill a 36mm sensor) is going to require microscope optics. This is no longer macro photography but photo-microscopy, which is beyond the subject of this article. This article deals with high-mag macro from a 1:1 to a 5:1 reproduction ratio. So what lenses do we need to accomplish this?
Nikkor AI-S Lenses
Below is a table of the best prime Nikkor AI-S lenses that can be deployed to accomplish 1:1 to 5:1 macro photography. For this specific discipline, I have created this table to show the differences in reproduction ratios for both full frame (FX, 36mm) and APS-C (DX, 23.6mm) sensor sizes given the same lens. I hope this table is useful in your selections process:
Remember to purchase only Nikkor AI-S glass, not some of Nikon’s budget glass, such as the older Series E glass. While many of you have heard of (and/or read articles about) reverse-lens macro photography before, most articles on this subject are usually directed at young, inexperienced photographers, without much means, and as such these articles typically attempt to recommend ‘the cheapest’ (and least-capable) gear possible for these entry-level readers. This article will be different; it will be directed to those photographers not on a budget–but who are after optimal results with really good equipment. Mind you, this equipment doesn’t have to be ridiculously-expensive; in fact, most of it is no more expensive than usual pro glass. Nonetheless, the focus of this article will be quality results over ‘cheap price.’ Since Nikon has so many wonderful, manual-focus lenses available (either brand-new or available at discounts on Ebay), take your time and look for the best option; just make sure you know enough about Nikkor lenses to buy wisely:
Nikkor AI-S manual lenses are Nikon’s best MF glass. Do not buy Series E lenses, as they are not the same quality, either in craftsmanship or in results. Nikkor AI-S primes will always have The Ear on them (refer to green arrow above). Although my direct experience reversing standard primes to achieve super-macro objectives centers around Nikon gear, as with sensor size, the principles will apply across platforms, to any system, provided the brand you use has the associated supportive connecting pieces. One more thing: many people ask me, “Why Nikkor AI-S manual lenses? Why not auto-focus lenses?” First, manual focus lenses are tougher, less-complicated, and are optically as good as (or better than) most AF lenses. Second, you lose all aperture control when you reverse-mount an AF lens … whereas you can still control the aperture on Nikkor AI-S lenses, even when they’re reversed. With that said, let’s jump right in and discuss the simple rings/adapters required to convert Nikkor AI-S lenses into “super-macro” tools:
Moving from 1:1 to 2:1 with the Nikkor 28m f/2.8 AI-S:
Now that we’ve discussed the concepts, and magnifications, let’s get into the material components necessary (1) to reverse your AI-S lens onto your Nikkor and (2) how to protect the exposed rear element—by creating a make-shift lens shade:
There are basically two additional pieces you will need to go along with your AI-S lenses: the Nikon BR-2A adapter and the Nikon BR-3 adapter. One attaches to the front filter threads of your lens, allowing the reverse-mount, the other acts as a lens hood for the exposed rear element. Once you connect the pieces together, you are now ready to take “super macro” images:
Moving down to 3.4x with the Nikkor 20m f/2.8 AI-S:
Keep in mind that Nikon’s standard front-filter size is 52mm. This is the dimension around which the BR-2A is based. The important lenses that you can reverse mostly have this dimension as well, including the 55mm f/2.8 Micro AI-S (1x), , the 50mm f/1.2 AI-S (1.1x), the 35mm f/1.4 AI-S (1.8x), the 28mm f/2.8 AI-S (2.1x), and the 24mm f/2.8 AI-S (2,6x). However, if you want to get even closer, you will need to move to a Nikkor 20mm AI-S (3.4x), but this now needs an additional adapter: the BR-5:
The BR-5 allows you to thread the 62mm front filter of the 20mm AI-S to the BR-2A (52mm), which in turn then mounts onto your camera. Thus assembled, your setup looks like this:
Now that we’re ready to shoot super-macro, let’s discuss some of the factors to be aware of when we shoot ultra-close.
Now then, this article has formed focused around prime lenses; however, for the field, and because the need for magnification can vary, it is often more convenient to use Zoom-Nikkors, which brings us to the next phase of this discussion: The Ultimate Field Macro Super-Zoom
** UNDER CONSTRUCTION ** (Anticipated completion date: September 3)