Going Under: Optimizing the Photography of Amber Inclusions

Why sharp images of insects in amber have more to do with physics than photography — and how water, glycerin, and a newly proposed immersion medium can open a clearer window into the age of dinosaurs.

Midge in amber: on the left, still shrouded in optical haze; on the right, clarity restored after 40 million years — thanks to a newly proposed immersion medium.

Anyone who has ever tried to photograph an inclusion in amber in fine detail knows that physics is not exactly on your side. Especially when, as in my case, the subject is a tiny male midge barely 1.5 millimeters long — its delicate antennae perfectly preserved in 40-million-year-old amber as if it were still alive. Those hair-thin filaments, only about 0.05 mm long and a few micrometers thick, are ruthless critics: they tolerate no blur, no scattering, no stray reflections. The moment anything in the optical path is less than ideal, their structures dissolve into a milky fog — like sugar in tea.

What are amber inclusions?

First things first: what on earth are amber inclusions? In short, amber is fossilized tree resin — ancient, hardened tears of conifers, resin that once oozed down trunks between 20 and 100 million years ago, dripped, stuck, solidified, and finally turned to stone. And it was in those sticky moments of Earth’s history that the magic happened: an insect, a spider, even a speck of pollen got trapped — and was preserved for eternity.

The piece of amber that has held this midge for 40 million years — marked by the arrow.

These inclusions, as such trapped organisms are called, are biological snapshots from an age long before humans, smartphones, or photography. The compound eyes that look back at us from within the amber may well have seen dinosaurs passing by. And the resin didn’t just encase these creatures — it captured them in astonishing three-dimensional fidelity, often so perfectly that under a microscope one can still see individual hairs or wing veins. Sometimes they look so lifelike that you instinctively hold your breath — as if the little creature might at any moment spread its wings and take flight.

Beautiful as this miniature world may be, photographing it is quite another story.

The problem with dry imaging

From a physics standpoint, the problem is obvious: between amber (refractive index ≈ 1.54) and air (1.00) yawns a massive optical gap. At every interface — amber to air, air to lens — light is partly reflected, partly refracted, and partly scattered. The greater the mismatch, the more the light goes astray. The result is a haze of stray light that overlays fine structures and destroys contrast. The strength of these reflections depends on the difference in refractive indices — the larger the jump, the stronger the reflection. Air and amber are worlds apart (1.00 → 1.54), whereas water drastically reduces that difference. The technical term sounds harmless enough — internal reflections — but in reality, these turbidity effects are the optical equivalent of fog on a windshield.

The experimental setup used for the images: focus stacking with 200 individual frames, combined in Helicon Focus (Method C, smoothing 1). Equipment: Novoflex Castel Micro with MicroTube, Mitutoyo objectives (5× and 10×). At 20× magnification, the amber defeated the optics — no image truly sharp. None of the shown test images were digitally edited in any way.

Amber is not just amber

To make matters worse, not all amber is created equal. Baltic amber contains far more microscopic inclusions, bubbles, and suspended particles than the generally clearer resins from the Dominican Republic (younger) or Myanmar (older). These tiny particles scatter light — exactly what you don’t want when photographing inclusions. As a result, working with Baltic amber is often a struggle against milky veils and low-contrast details.

From my experience, these problems — scattering, reflections, light haze — are far more pronounced in Baltic amber than in others. In some cases, Dominican or Burmese amber even yielded worse results under water immersion than in a dry setup. That’s why this article focuses specifically on Baltic amber — the type most commonly found in European collections and the commercial trade.

Why Photographing Baltic Amber is so Difficult

Put simply: because it looks older — in both the best and worst ways. Baltic amber, roughly 35 to 45 million years old, has been through a lot in its geological lifetime. It is more oxidized, contains countless microscopic gas and fluid inclusions, and its resin structure is often finely grained. Under the microscope, one sees not only stress cracks but also innumerable tiny bubbles, dust particles, and traces of crystallization — all little troublemakers that scatter light in every direction. If the specimen happens to come from Bitterfeld, its geological history was even more turbulent: over the eons it was re-deposited multiple times, mechanically stressed, and fractured. That often shows up as a network of microcracks and internal fractures.

Baltic amber — warm in tone, but photographically demanding. Its fine resin texture and microscopic bubbles scatter light as if it were trying to keep its secrets for a few million years longer.

For photography, that means the path of light resembles an expedition through a restless micro-world. Every inclusion, every bubble, every boundary surface bends and scatters the light. The result is a faint milky haze — as though someone had breathed the thinnest mist across the lens.

You might say Baltic amber is the charming but slightly unpolished character actor among resins: tricky to illuminate, full of optical quirks — yet often rewarded with spectacular inclusions that make every bit of effort worthwhile.

The Comparison: Dominican Amber

Completely different is the amber from the Dominican Republic. At only about 16 to 20 million years old, it is far younger and chemically less weathered. Its resin is homogeneous, clear, almost glass-like — a dream for photographers. Light goes in, light comes out, and little in between causes trouble.

Dominican amber — young, clear, and almost glassy. Thanks to its homogeneity, inclusions can be captured here with higher contrast and finer detail.

Its origin likely lies in the resins of tropical Dipterocarpaceae, hardwood trees whose exudates are naturally more stable and less acidic than those of the Baltic pine relatives (Pinites succinifer). This resin polymerized more calmly, formed fewer micro bubbles, and remained astonishingly clear over millions of years.

You could say Dominican amber is the flawless studio guest — cooperative, photogenic, and always perfectly lit.

And Burmese Amber?

He’s the elder statesman of the trio — an impressive 95 to 100 million years old, from a time when dinosaurs still roamed tropical forests. And yet, it is often so clear that one can hardly believe its age.

Burmese amber — as old as the dinosaurs, clear as liquid honey. Its chemically stable resin makes inclusions appear to float freely, making it far less demanding to photograph.

How is that possible? Burmese amber likely originated from ancient Araucariaceae or related tropical trees whose resin was extraordinarily stable. It contained fewer polar compounds, no succinic acid, and hardened evenly — with no emulsions, no trapped liquids.

The environment helped as well: a warm, tropical, relatively dry climate that allowed the resin to evaporate quickly and resist oxidation. Even the diagenesis — the slow transformation of resin within the sediment — was gentle: no groundwater, no aggressive chemicals, no severe pressure fluctuations.

The result: glass-clear pieces of golden to reddish amber in which tiny prehistoric insects seem to float in liquid honey. One might say Burmese amber simply had the best starting conditions.

Despite its great age, it’s so clear you could almost believe it dripped from the tree just yesterday.

More Light, Less Sharpness — The Paradox of High Numerical Aperture

The obvious idea: just use an objective with a higher numerical aperture (NA) to resolve finer details — after all, that’s what NA stands for. Unfortunately, in this case, that approach only makes things worse. As NA increases, the light enters at steeper angles, and reflections at the air–amber interface multiply. The result, paradoxically, is that the sharper the lens, the blurrier the image becomes.

The male midge in Baltic amber, dry images: left with a 5× objective, right with a 10×. The higher numerical aperture brings in more light — but also more scattering and loss of contrast.

In practice, this becomes painfully obvious: With the Mitutoyo M Plan Apo 10× (NA 0.28), the inclusion already looks milky and soft where the 5× (NA 0.14) still appears crystal clear. At 20× (NA 0.42), it gets worse — the image is practically unusable. The amber inclusion itself hasn’t changed; the physics has.

Amber, of course, is optically clear. The problem lies not in the material, but in the light’s journey through it. A lens with a higher numerical aperture collects light at wider angles. That means: while the 5× objective works mostly with rays entering almost straight, the 10× also gathers light traveling diagonally through the amber. And that’s where the trouble starts:

Surface reflections:Amber’s refractive index is about 1.54; air’s is only 1.00. Every light ray striking that interface at an angle is partly reflected and partly refracted. The steeper the angle, the stronger the reflection — and the more stray light reaches the camera. That’s the essence of Fresnel reflection.

Internal scattering:Within amber are microscopic density variations, inclusions, and ancient resin channels. When light enters almost perpendicularly, these have little effect. But at steeper angles (i.e., higher NA), the light is scattered sideways inside the resin. That scattered light overlays the true image, producing the characteristic milky haze.

Back reflections between object and lens:Between the surface of the amber and the lens sits a thin layer of air. At oblique angles, it behaves like a tiny mirror: some light bounces back and forth repeatedly — summing up to a dull, contrast-killing gray fog.

The outcome: the 10× objective “sees” more light than the 5×, but much of it is wrong light — scattered or reflected. To the naked eye the amber still looks clear, because our visual system subconsciously filters out stray light. The camera, however, adds it all together mercilessly.

The Idea of Using Water

Anyone familiar with microscopy knows the principle: when you want to avoid stray reflections, remove the air between the objective and the specimen. In classical microscopy, a tiny drop of immersion oil sits between the slide, cover glass, condenser, and objective, creating a continuous optical path — glass → oil → glass → oil → glass — without the abrupt jumps in refractive index where light loves to misbehave. The oil’s refractive index (≈ 1.515) nearly matches that of glass, eliminating most internal reflections and scattering.

What immersion oil does for microscopy, water does for amber: It bridges refractive indices, cuts down reflections — and suddenly you can see what before was only a hint.

For amber inclusions, however, an oil bath is not a great idea. Even a small drop of immersion oil on the surface can do little more than fill scratches and tiny irregularities — it won’t solve the underlying optical problem. The geometry is entirely different: amber surfaces are slanted, rarely parallel, and the air gap between specimen and sensor introduces distortions that can easily destroy fine detail. Prolonged contact can also attack the surface or cause discoloration.

So it’s better to reach for something more innocent — water. With a refractive index of about 1.33, water lies much closer to amber than air (1.00) and thus reduces light scattering significantly. The effect is immediately visible: higher contrast, better clarity, more stable color. On top of that, water is easy to handle, rinse, and reuse — a practical dream. For us, that means the inclusion gains contrast, the haze largely disappears, and details emerge that were simply invisible in dry images.

The concept of an immersion bath isn’t new. Paleo-entomologists, for instance, have long used water to photograph amber inclusions. Usually, however, they work with a vertical setup — camera pointing straight down, the specimen resting in a shallow dish just below the water’s surface. Sounds good in theory, but it comes with pitfalls: the water surface itself acts as an extra lens, distorting the image and creating new reflections. And once that surface starts to move, things only get worse. Personally, I prefer working horizontally, with a precise, vibration-free focus-stacking setup — far more comfortable than the acrobatics a vertical microscope demands.

So I built myself a tiny photo tank — from five thin glass plates that once lived inside old medium-format slide mounts in my archive. A bit of aquarium silicone later, and I had a miniature aquarium for optical experiments.

Baltic amber in a water bath — here, it’s not the insect that’s underwater, but the physics: fewer reflections, more clarity.

Interestingly, this technique predates my fascination with million-year-old amber inclusions — which I owe to a suggestion by Alex Beigel (many thanks!). Back then, my goal wasn’t prehistoric insects but the inside of a light-emitting diode encased in transparent plastic. Despite grinding the plastic surface flat in the desired focal plane and polishing it to a mirror finish, I kept battling reflections and stray light.

The water bath in my mini-tank solved it instantly: the image became crystal clear, high-contrast, razor-sharp — though only up to about NA 0.28 (Mitutoyo M Plan Apo 10×). At the 20× equivalent (NA 0.42), the familiar white haze returned. But more on that later.

I fix the amber to the bottom of the tank with nano tape — it holds firmly, can be reused once dry, and leaves no residue. Then I carefully fill the tank with water, place it on the focus-stacking stage, and begin the shoot (watch for air bubbles; a small pipette works wonders to remove them).

Left: dry image (refractive index n = 1.0); right: water immersion (n = 1.33), both at 10×. Even simple water drastically reduces reflections and reveals fine structures more clearly.

The result is striking: the fine antenna filaments stand out more distinctly against the golden amber background, and the haze is much weaker. Still, with n = 1.33, water is a long way from amber’s 1.54 — a compromise. It scatters less light, but still enough to obscure the tiniest details. Anyone wanting to truly see what’s inside the midge inevitably ends up turning to glycerin.

The Step into Glycerin

If water helps, then a medium with an even higher refractive index should help even more, I thought. Glycerin (chemically: propan-1,2,3-triol) has a value of about n ≈ 1.473 — quite close to amber. It’s also non-toxic, odorless, inexpensive, and easy to obtain (in any pharmacy or online, usually as plant-based glycerin).

Baltic amber in a glycerin bath — thick as honey but optically a dream. The refractive index moves closer to amber’s, and fine structures finally come into true focus.

All that sounds ideal — and it almost is. But glycerin has personality: as thick as winter honey and just as stubborn when you try to move it without trapping air. That’s why I strongly advise against diluting it with water. It may sound sensible in theory — it becomes more fluid — but in practice you get a cloudy emulsion full of streaks and bubbles. And with glycerin’s viscosity, those bubbles rise about as fast as lead balloons. Plus, the refractive index drops again.

I therefore use pure glycerin. I pour it slowly, letting it run down the slanted inner wall of the tank — never straight in. That way, no bubbles form, and the medium settles evenly around the specimen.

It’s also important to keep the optical path through the glycerin as short as possible: the amber should rest right behind the front glass pane, not in the middle of the tank.

The result: Glycerin beats water

Comparing dry, water, and glycerin images of the same inclusion tells a clear story. The jump from dry to water immersion is dramatic; from water to glycerin it’s subtler — but crucial. In glycerin, you can work with higher numerical apertures — precisely where water and air already give up.

In the case of the midge, the limit in air and water was NA = 0.14 (Mitutoyo 5×). In glycerin, however, a Mitutoyo 10× with NA 0.28 worked effortlessly — bringing not just more magnification but notably more resolution. The finest antenna filaments, once lost in a haze of light scatter, now appeared crisp and almost three-dimensional.

Left: water bath (n = 1.33); right: glycerin bath (n = 1.47), both at 10×. With glycerin’s higher refractive index, scattering and reflections drop even further — the tiniest antenna hairs emerge sharper and with greater contrast.

At around NA 0.4 (Mitutoyo 20×), however, the haze returns — not because the medium fails, but because amber itself sets the limit. The steeper the light enters, the more it scatters inside, no matter how perfectly the refractive index is matched. Physics enforces its own boundary for sharpness.

Closer to Amber Light: Clove Oil

The refractive index of glycerin (n = 1.473) is good, but not perfect. Amber sits at n = 1.54–1.55.So I asked myself: are there liquids that come even closer — without dissolving the fossil in the process?

Baltic amber in a clove oil bath: Here the refractive index almost exactly matches amber’s — reflections vanish, details light up. Only the smell says dentist, not lab.

Clove oil (main ingredient: eugenol) seems to be the physical ideal: n = 1.541–1.543.The difference from amber is practically zero, and its faint yellow tint doesn’t affect the image — especially at short optical paths through the oil. In practice, though, it’s… let’s say, olfactorily ambitious. Anyone who’s used it will have the scent of dental drills and Christmas spice in their nose for hours. It’s also expensive. For short sessions, however, it’s brilliant: the images are stunningly crisp, and reflections nearly disappear. Cleaning, on the other hand, is more challenging (rinse thoroughly with warm water, then wash with soap), and labels or painted surfaces nearby dissolve faster than you can look. My amber specimens showed no visible damage, though the surface felt slightly different afterward. An acrylic block I used as a volume filler in order to save clove oil, however, developed fine stress cracks on all sides. Still — for single high-quality shots, it’s absolutely worth the experiment.

You should, however, limit the immersion time. My test series, across different magnifications, lasted about an hour — with no visible harm to the amber — but it’s safer to stay well below that. And before you let your best inclusion take the plunge, practice on a less precious piece. And don’t expect your nano tape to hold — clove oil dissolves its grip almost instantly.

Also, buy only true clove bud oil — the essential oil distilled from unopened flower buds — not clove leaf or clove blossom oil. The latter contain less eugenol and more foreign compounds, making them darker and less suitable. The unopened clove bud is rich in eugenol, but once the flower opens, most of it disappears.

Comparison: glycerin (n ≈ 1.47, left) and clove oil (n ≈ 1.54, right), both at 10×. With nearly perfect refractive matching, reflections disappear almost entirely. Both tame stray light, but clove oil reveals the finest filaments with even greater clarity — optically perfect, if you can forgive the aroma.

Benzyl benzoate

After the experiments with clove oil, I was torn. The photographic results were brilliant — the smell, anything but. And it lingered for hours. It also became clear that this supposed miracle fluid was no ideal partner for amber — or for my nose.

So I went looking for a medium that could deliver the same optical magic without the olfactory side effects. Benzyl benzoate — also known as benzoic acid benzyl ester — has a refractive index of n = 1.568, and it’s something of a discreet gentleman among immersion media: refined, reliable, odorless, and chemically well-behaved. Its refractive index is slightly higher than amber’s ideal (n ≈ 1.54), but that’s easy to forgive. In return, it’s stable, clear, non-hygroscopic, and leaves the amber untouched — qualities that can’t be said of every contender in this field.

Baltic amber in a benzyl-benzoate bath: As clear as clove oil, but without the scent, without the risk — and used here for the first time as a dedicated immersion medium for amber photography.

That said, note that benzyl benzoate isn’t non-toxic. The label says it plainly: “Do not swallow. Harmful to aquatic life. Keep away from children. Wash hands thoroughly after use.”You should also avoid eating or smoking while working with it.

In my experience, benzyl benzoate delivers a hint more fine detail than clove oil. The difference alone wouldn’t be decisive — but combined with its lack of smell and much lower cost, it becomes a clear winner. It is, by far, my preferred immersion medium for photographing inclusions in Baltic amber: optically superb, chemically safe, and practically pleasant to use.

Comparison: clove oil (n ≈ 1.54, left) and benzyl benzoate (n ≈ 1.568, right): Minimal overcorrection, maximum fidelity — the best medium yet for amber imaging. Both are nearly perfect, but benzyl benzoate adds a trace more clarity — while staying odorless and amber-friendly.

Other Potential Options

For those who wish to match amber’s refractive index even more precisely, there are several additional options — though I haven’t tested these myself:

Wintergreen oil (methyl salicylate, n ≈ 1.536)

A classic of old-school microscopy. Pleasantly sweet-smelling, but not without issues: it can attack varnishes and leave residues. Mixed with benzyl benzoate, the refractive index can be finely tuned.Anyone with a pipette and a refractometer can practice a little alchemy here — and with patience, reach near-perfect optical matching.

Pure eugenol (n ≈ 1.54)

Technically, this is the active ingredient of clove oil. Buying pure eugenol avoids the essential-oil impurities (and some of the smell). It’s chemically more reactive than glycerin, so it’s suitable only for short immersions — but the image quality can be spectacular. The price, too.

Cargille index-matching liquids

For those who crave precision: Cargille offers index-matching fluids in fine increments — 1.540, 1.545, 1.550, and so on. They deliver theoretically perfect results, but are expensive and sometimes contain solvents that attack plastics. In short: high-end gear for those who know what they’re doing — and are willing to pay for it.

Conclusion: What Really Matters

Anyone photographing amber isn’t just fighting blur — they’re fighting light scatter. An immersion bath isn’t a gimmick; it’s the logical consequence of physics and optics. Even plain water brings a huge improvement. Glycerin makes the decisive leap — and will likely be more than enough for most serious photographers. Only those as perfection-obsessed (and perhaps as reckless) as I am will want to push further — simply because it can be done. And for that kind of curiosity, benzyl benzoate is the medium of choice: clear, stable, affordable — and, quite literally, a fresh way to see deep time.

Five imaging methods, one amber inclusion, magnification 5×: From dry (top left) through water, glycerin, and clove oil to benzyl benzoate (bottom left), the differences in clarity, contrast, and depth continue to increase — the closer the refractive indices, the clearer the window into the past.

Five media, double magnification: At 10×, the impact of immersion fluids on fine detail becomes strikingly clear. Benzyl benzoate (bottom left) delivers the cleanest transparency and finest structural definition.

No rules, only realities

The combinations of magnification and numerical aperture given here shouldn’t be seen as strict rules. It would be tempting to say: “Dry or water works up to 5× (NA 0.14), glycerin up to 10× (NA 0.28).” But that’s not how practice works. Too many variables are at play. Amber is a natural material — and therefore anything but uniform or predictable. Density, structure, inclusions, even chemical composition vary from piece to piece. A Baltic amber behaves differently from one from Myanmar or the Dominican Republic. Even within a single piece, clarity can change dramatically, and the depth of the inclusion matters: the farther it lies below the surface, the more material light must travel through — and the stronger the scattering and absorption.

Even tiny suspended particles or micro-cracks can affect contrast. Each piece of amber is its own optical micro-universe. So the values given here are not universal laws but my personal empirical observations — guideposts showing what’s achievable under certain conditions. Or, put differently: you can use them as signposts, not as a map.

But nothing comes for free in amber photography either. Where benzyl benzoate, with its higher refractive index, delivers extra sharpness, it also turns up the contrast — sometimes a little too enthusiastically. What works like a blessing in cloudy, light-scattering Baltic amber can quickly become a curse in crystal-clear material.

In the first case, the contrast boost acts like an optical cleaning: the haze disappears, fine structures emerge, and the image suddenly looks as if someone had wiped away forty million years of dust. In the second, however — with nearly perfect, transparent amber from Myanmar or the Dominican Republic — the picture becomes too harsh, too pronounced, almost unnatural. Highlights and reflections sharpen as well, and can start to distract. Here you have a solution without the problem, and in those cases, less is more: glycerin gives a calmer, more natural rendering.

So, as always, experiment. Start with a dry shot — and if it looks flat, feel free to let it take a bath: first in glycerin, and if that’s still not enough, in benzyl benzoate.

Chironomid midge (Chironomidae), female, Baltic amber, 10×. Left: imaged in glycerin (n ≈ 1.47). Right: imaged in benzyl benzoate (n ≈ 1.57). Both show heavily cropped sections from larger focus stacks. Here again, the benzyl benzoate immersion reveals a striking gain in fine detail — even the minute gaps between individual ommatidia appear three-dimensional. Yet the bright highlights also show that the increased contrast can become distracting, even in Baltic amber — particularly when the inclusion lies close to the surface and the optical path through the material is short. In such cases, a glycerin image may suffice; with careful digital post-processing (contrast adjustment and sharpening), it can often produce a more balanced and natural result.

Fungus gnat (Mycetophilidae), Dominican Republic amber, 10×. Left: imaged in water (n ≈ 1.33). Right: imaged in benzyl benzoate (n ≈ 1.57). Both are heavily cropped sections from the same focus stack. Dominican amber is almost optically ideal — clear, homogeneous, and virtually free of scattering. The benefit of immersion media is therefore smaller, yet the benzyl benzoate image still reveals slightly finer surface textures and hair structures without excessive contrast. In such clear resins, the optical path alone often provides near-perfect clarity — the immersion adds not correction, but refinement.

Benzyl benzoate even allows a clear view into unpolished amber — an excellent way to assess the quality of a suspected inclusion. What was previously visible only as a vague shadow beneath the natural surface becomes sharply defined and richly detailed with just a drop of benzyl benzoate.

Final Thoughts

For most purposes, I’d say glycerin is the new water. It’s easy to handle, inexpensive, gentle on amber, and produces images that look almost three-dimensional — especially when paired with higher-NA objectives that water still can’t fully support. And when you finally see the delicate antenna filaments of a tiny midge — frozen in amber for forty million years — rendered razor-sharp, as if it might twitch at any moment, you understand why the effort is worth it.

But for those who want to go a step further, there is a medium that, until now, has never been mentioned in this context: benzyl benzoate. Through my experiments — and through this publication — it is being introduced here for the first time as an immersion medium for amber photography.

Its refractive index sits slightly above that of amber, but its chemical stability is excellent.It’s clear, odorless, affordable, and in practice delivers results at least as good as clove oil — often a touch better — yet without its typical side effects or scary price tag.

This makes benzyl benzoate a new and reliable option for the micro-photography of amber inclusions: a simple, safe, and highly effective solution — one that bridges the gap between scientific precision and practical everyday use.

Every piece of amber is a microcosm of light and time — a drop of eternity where beauty, transience, and history begin to glow.

Ultimately, the microphotography of life in amber is far more than a technical exercise – it is a quiet dialogue that bridges forty million years. With every advance in optics and light, details emerge that nature has kept hidden since the Eocene. And sometimes, discovery doesn’t arise from a laboratory, but from curiosity, patience – and a single drop of the right liquid.

Benzyl benzoate may be an unassuming substance with a decidedly unpoetic name, yet in the silent world of ancient resin it opens a new window – one through which we can see the depth of time a little more clearly, and perhaps with a touch more reverence.