Notes on Zeiss 20x60S Stabilized Binoculars

By Paul Knight on October 1, 2015 — 19 mins read

For three hours we followed the trail through the woods. The scene was typical of Northeast Georgia this time of year; a leafless canopy of trees was over our heads while we walked on a carpet of damp leaves. The sky was clear and the sun shone through with relative ease. We would occasionally hear a mountain bike making its way up the road near the trail head, but other than that we had Chimney Mountain to ourselves as we headed for the top. My wife carried our lunch and water; I carried my Zeiss 20x60S image-stabilized binoculars.

The top of Chimney Mountain provides almost 360 degree views of Appalachia. As I would later be able to estimate on Google Earth we could see about 20 miles in every direction. As we were setting our backpacks down, a shadow on the ground caught my attention. I unhurriedly pulled out the binoculars as a lone buzzard circled us. I wanted to take a closer look at the creature. He was fast, and the relatively narrow field of view through the binos made it difficult to capture him at first. But once I got hold of him and stabilized the image I was able to track him with ease. It felt like those cameras you see on tv that track a golfer’s ball. The image was perfectly crisp and smooth.

Leaving the buzzard alone, I turned to the horizon at my south. I wondered if I would be able to see any landmarks to give me a sense of where I was. Within 20 seconds I had my answer. There, about 20 miles away, were the two water towers in my home town. A couple miles to their south was the chicken plant. Here I was, on the extreme north end of Habersham County, and I was easily able to identify objects on the extreme south end–and with a handheld device nonetheless.

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After returning home and eating a late dinner, I was eager to try the binos out on decently dark skies. Up until that point I had only been able to use them under the glow of the Atlanta sky. I had a meeting with Orion and I didn’t want to be any later than I already was, especially during this season. It would be the first time I had seen the great Orion Nebula with the binos.

I walked outside and let my eyes adjust to the darkness for a while. Once my anticipation overtook my patience I lifted the binos. Within seconds I was looking at one of the most beautiful views of the night sky I had ever seen. Orion’s nebula shown like a blooming flower with one pedal casting a shadow on another, lending a sense of depth to the composition. The stars in the vicinity shined with the intensity of welders’ spatter. The crispness and contrast of the image was simply beautiful. And again it was with the same device that just hours earlier allowed me to spot my hometown chicken plant.

Mobility, versatility, and power is the name of the game with these. With something no larger than half a loaf of bread and no heavier than a few cans of soup, these binos provide a feast for the eyes. In the three months I had owned these binoculars up to that point I had not one ounce of buyer’s remorse. That day on the hike and night under the stars simply affirmed my suspicion that I had discovered the most incredible optical device I had ever owned.

Orion Sketch - 20x60

Above: Sketch of the Orion Nebula as seen through my Zeiss 20x60S binoculars. Approximate sketch time was 30 minutes. Post processing in Photoshop to invert the colors.

Why I Bought These

I didn’t realize it then, but when I was in high school I had all the free time in the world. Part of that free time was spent setting up and taking down my Celestron C8 and Losmandy GM-8. As I got older and my free time diminished, I eventually realized that the C8 was no longer fitting my needs. The views were amazing, but I could no longer afford the time it took to set it up. And I didn’t have an observatory to leave it up.

A couple years ago I sold my C8 and GM-8 and started the hunt for a grab-n-go setup. What I landed on was a beautiful ensemble: an AstroTech AT72ED refractor, a Half-Hitch FTQ mount, and a Manfrotto 475b tripod. I had carefully selected and limited my equipment to fit inside just two cases: one case for the tripod and mount, and another case for the refractor and all accessories. I could take everything in just one trip. It was a beautiful, efficient, and effective setup, and I enjoyed it for a year. But over the course of that year I realized something about myself. As quick as the little refractor was to set up (it took only about 5 minutes), I finally admitted to myself that I had reached a point in my life and my hobby where I wanted zero setup time. That meant I needed either one of two things: 1) an observatory or 2) a pair of binoculars. While an observatory is an ultimate life goal for me, in the short term I opted to place my hobby strictly in a pair of binoculars. But which pair?

*

My dad and I had always dreamed of owning a pair of Zeiss 20x60S binoculars. We loved the Classic Dialyt design, and over probably 20 years we owned a number of different models in that line including 8×30’s, 7×42’s, and 8×56’s (I still happily own the 7×42’s). For us, the primary problem with the 20×60’s was the cost—at $8,000 new, it was hard to justify selling a car for a pair of binos. But after my dad passed away last October, I decided to cast all financial concerns aside and to purchase the 20×60’s in his honor. That happened in December when I found a used pair on eBay. Since then, I have not had a second of buyer’s remorse.

I have enjoyed the views the 20×60’s have given me, but I have equally enjoyed simply studying their mechanics. Below, you will find not just a review but also my attempt at explaining how these things actually work. They are a marvel of ingenuity and engineering, and I am beyond proud to own one of the most—if not the most—mechanically advanced binoculars ever made.

Disclaimer:
I am writing this as an amateur astronomer with a life-long interest in physics and astronomy. However, as an architectural and urban designer I make no claims to provide you with a completely accurate or exhaustive understanding of this instrument. I am only sharing my passion to the extent that I can. That said, I welcome any feedback or knowledge about these binoculars that you can share. I will be happy to update this page as I learn more from you.

Basic Information

Technical Data:

From Zeiss.com

  • Magnification: 20 x
  • Effective Lens Diameter: 60 mm
  • Exit Pupil Diameter: 3 mm
  • Twilight Factors : 34.6
  • Field of View at 1000 yd : 156 ft
  • TFOV (not from Zeiss): 2.79 degrees
  • Subjective Viewing Angle: 60 °
  • Close Focus in Ft: 45.93 ft
  • Diopter Adjustment Range: +4 | -4 dpt
  • Pupil Distance: 57 – 73 mm
  • Eye Relief: 13 mm
  • Lens Type: Achromat
  • Prism System: Porro
  • Water Resistance : Sealed against spray water
  • LotuTec® : no
  • Nitrogen Filling : no
  • Functional Temperature in °F : -4 | +104 °F
  • Height in Inch : 10.8 inch
  • Width in Inch at an eye width of 65 mm: 6.33 inch
  • Weight in Use in oz: 58.55 oz
  • Cost new: $7,999

Usage Suggestions:

From Zeiss.com

  • Birdwatching 4/5
  • Hunting 3/5
  • Nature observation 2/5
  • Events 1/5
  • Traveling 0/5
  • Marine 3/5
  • Astronomy 5/5
  • Outdoor activities 3/5

My Equipment

I confirmed with Zeiss that my binoculars were manufactured in 1993. They said that the specs of my model are exactly the same as those that are currently produced.

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20x60 and 7x42
20x60 and 7x42
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The binos come standard with a hard case that’s fitted perfectly for them. It provides excellent protection. I like to keep a cleansing cloth and microfiber cloth in the case at all times.

As an alternative to the hard case, I purchased a small, soft leather case for when I take these binos on a hike. Some people have expressed apprehension over taking these binos on a hike, but I didn’t buy them to not use them. Hopefully I don’t fall on my back in a creek somewhere, but if that ever happens I’ll pay Zeiss to fix them and life will go on.

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I purchased a pair of 3-1/4″ diameter solar filters from Thousand Oaks. The clearance between the objective lenses on the binoculars is narrow due to the casing, but it is just large enough to accommodate the thickness of the solar filter casings together. Because the filters have to be snug in the center, they overhang the outer edges slightly. I accommodated for this by installing felt liners only on one side.

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As a couple of accessories for the binoculars, I have a WalkStool and a Manfrotto Compact Tripod. While not necessary, they make observing a little more comfortable. The binoculars are heavy, so the tripod takes care of that. It may seem crazy and counter intuitive to consider using a tripod, but I have to say once you engage the stabilizer the image is sharper and more stationary than anything you’ve ever looked through.

OLYMPUS DIGITAL CAMERA

The binoculars attach to the tripod by way of a small, circular disc that came with the tripod. The disc screws into the underside of the binos and then locks into place on the tripod head. While the connection appears to be perfectly secure, it is anything but stable. The binos wobble severely on the tripod head which is a bit unnerving, but they’re not going anywhere. Once the stabilizer is engaged the wobble goes away completely. One benefit to a loose connection is the slight freedom of movement for the binos–rather than having to disengage the tripod head you can just tilt the binoculars one way or the other.

K04_4717-bw OLYMPUS DIGITAL CAMERA tripod-head-clamp

Finally, I purchased a Zeiss 3×12 tripler to attach to the eyepiece of the 20×60’s. The tripler is well made and carries all the quality you would expect from a Zeiss product. However, when attached to the 20×60’s the result is not good. The image lacks the crispness that the 20×60’s normally provide; it’s dark, dull, and cumbersome. I tested this on the sun, Venus, Jupiter, and Saturn. Venus was surrounded by a severe purple halo. I couldn’t make out the cloud bands on Jupiter as it was just a large, dim ball. Without the monocular attached, Saturn was nice and crisp with its rings easily distinguishable; with the monocular it became more of an elliptical blob. I was careful to focus and attached and detached the monocular numerous times to make sure I wasn’t doing something wrong.

It’s too bad. Since I don’t have a telescope I was really hoping I could convert the 20×60’s into a 60 power 60mm scope. I wasn’t expecting a miracle by any means–I knew going into it that a dedicated telescope would be the best thing for higher-power viewing. I just wanted an “emergency” 60x just in case, but the quality of the image was so bad that it just wasn’t worth keeping.

I sent Zeiss an email requesting that they fabricate a 2×12 monocular to add to their line up of products. If you have had a similar experience with the 3×12 as I have perhaps you should consider doing the same.

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The Mechanical Stabilizing System

I will get to the optics a little later. First, I want to discuss what really sets the 20×60’s apart from every other bino on the market: the mechanical stabilizing system.

If a Zeiss representative told me that these binoculars are powered by magic I would believe them. The stabilizing mechanism is incredible. At 20x unstabilized, the moon is a jittery bouncing ball. It’s essentially impossible to focus on anything for any meaningful amount of time. However, as soon as I engage the stabilizer everything floats. The first time I did this I could feel my heart rate increase—but with Zeiss’s magical stabilizer I couldn’t see my heart rate reflected in the optics. It’s simply amazing.

From what I have observed, in hand-holding high-power binoculars there are three classes of tremors that cause the image to shake:

  1. Hand tremor
  2. Heartbeat
  3. Body sway

The effectiveness of the stabilizer varies based on the viewing angle. Here are my estimates of tremor reduction at varying degrees of altitude:

Viewing Altitude | Hand Tremor | Heart Beat | Body Sway
0-20 99% 90% 10%
20-60 99% 70% 5%
60-90 99% 20% 0%

With the binoculars unstabilized, hand shake is ever-present, heartbeats obscure the image regularly and periodically, and there is an overall sway of the image. With the binoculars stabilized, the only real noticeable tremor is due to body sway. Given the limited motion and range of the mechanics this makes since.

The stabilizer at 20x is equivalent to an unstabilized 3x Bino. I am officially spoiled–even my 7×42’s are too shaky for me now.

Stabilization Mechanics

When I first received these binos, I put on a headlamp and peered inside the casing through the objective lenses. I sat there for an hour, subtly shaking the binos, engaging and disengaging the stabilizer, trying to figure out how they worked. At the end of that session, I figured magic was good enough. Then I found the patent.

Patents are great. They protect the intellectual properties of inventors and investors, but they also allow people like me to learn more about the devices they use. You can download your own copy of the patent here. While this patent is filled with technical jargon, I was able to glean a satisfactory level of understanding for myself. Let’s see how well I can translate that for you.

First, here the major components of the binocular:

  1. Binocular casing
  2. Objective lenses
  3. Stabilizer
  4. Eyepieces

The stabilizing system is composed of the following parts (refer to the diagrams below which I produced by color-coding the drawings from the patent):

  1. Moveable double holder (grey): the frame that pivots around when released and holds the other stabilizing components.
  2. Base frame: the moveable double holder is attached to the base frame via a pivot; the base frame, in turn, is attached to the casing of the binoculars.
  3. Spring joint (yellow): about half of the patent discusses this device. This makes me suspect that it is very important, but I do not know why.
  4. Magnetic damping device (orange): this includes the magnets at one end of the moveable double holder and wires that trip based on the eddy current that is generated. The magnets also act as a counterweight for the inverting prism system at the opposite end of the double holder.
  5. Inverting prism system (blue): these optics manipulate the light path between the objective lenses and the eyepieces. As the magnetic damping device does its magic, these optics adjust accordingly. Also, these prisms act as a counterweight for the magnetic damping device.
  6. Stabilizer Color Keys

The stabilizer fits between the objective lenses and the eyepieces. Light enters through the objective lenses then gets “stabilized” before entering and exiting the eyepieces. See the two light-path diagrams below. These were produced by overlaying the patent diagrams onto images of my binoculars, scaled appropriately.

Patent Diagram 1 Patent Diagram 2

Here’s what I cannot explain (to me this is still in the “magic” category):

1. The spring joint. It is unclear to me why this is explained in such great depth in the patent. The concept seems simple enough: it’s the thing that releases or locks the moveable double holder. It seems like that should be relatively easy and straight forward mechanism to accomplish that.
2. The magnetic damping device. I know what magnets are. I know what eddy currents are. I know in general terms how these things could dampen vibration, but seriously–how the hell do you calibrate these forces? Even if a Zeiss engineer sat me down to explain it to me I am pretty sure it would be beyond my comprehension.

Optics

Over perhaps 18 years I have owned an 80mm ED Orion refractor, a C8 with XLT optics, and an AstroTech AT72ED. They all gave me fine views, but until I looked through this pair of Zeiss 20×60’s I had no idea what I was missing. I had conditioned myself to observe stars as little blobs—albeit tiny little blobs. I suppose I thought “well, that’s what stars look like through our atmosphere.” When I saw the perfect points of light through these binos I was amazed. Stars are points—perfect, zero-dimensional points. It took me 18 years to see how important that observation really is.

All of that said, the view is not crisp to the edge. There is some obvious distortion. I would say the inner 80% of the field of view exhibits no obvious distortion. The remaining 20% gets progressively worse as you look to the edge, culminating in little streaks.

Note: Given the length of this article I am starting to feel the effects of writing fatigue. I’ll update this section with more material one day. Or maybe someone else can review the optics for me?

What can I see with these?

Planes

I am amazed at how crowded the skies are. With the naked eye, I only notice high-altitude jet fuel trails, low-altitude planes coming in for a landing, or helicopters making emergency flights to Piedmont Hospital. I’ll pull the binos out to take a closer look at these and undoubtedly I will always find something else flying around that was invisible to me otherwise. There are planes everywhere. I know I’m in Atlanta which is a big flight hub, but I just didn’t realize how crowded the skies really are around here until I got these binos. I suppose in a few years I’ll be saying the same thing about drones.

From the top of Stone Mountain, with the 20×60’s I can easily watch planes land at Hartsfield Airport 20 miles away and I can see them all taxiing up in the sky for landing. When a plane flies over Stone Mountain I would swear I could see someone waving if I knew exactly where to look.

The Moon

The view of the moon is just incredible. For my first look at it through the 20×60’s, I was fortunate to have a waxing crescent. The shadow side was subtly illuminated, rendering the moon as a heavenly sphere. At 20x stabilized, every detail is visible; unstabilized, don’t even bother.

See simulation below:

20x60 vs 7x42 FOV Compare Moon Night

The Sun

Twenty power seems to be the turning point for resolving sunspot details. At 7x, there’s no point looking at the sun. You’ll just see a yellow bouncing ball that has a few black specs on it. However, at 20x details come into view. You can easily see sunspot details, granulations, and those white water vapor regions along the edge of the solar disc.

See simulation below:

20x60 vs 7x42 FOV Compare Sun

The Planets

  • Jupiter: Jupiter appears as a bright, large disc surrounded by its four galilean moons. Based on their relative sizes, brightness, and color, I can easily distinguish one moon from another. I have tried and tried to observe cloud bands on Jupiter, but have not been able to due to the intense brightness. Even on a night of good seeing, Jupiter appears to be just too bright.
  • Venus: Because Venus is so bright it is difficult to observe phases, but it is possible.
  • Saturn: “The rings and the space between the rings and the planet are barely discernible. This is a 20x handheld binocular—it’s impressive that they’re discernable at all but it’s not a particularly impressive or majestic view. Titan is just visible as a faint tiny point.” That was written during unstable seeing conditions. During a night of clear seeing, the rings were easily discernable. The gap between the planet and the rings was obvious. This observation highlights the following: when viewing planets at 20x there is only so much you can see (there is no “detail”, just the thing itself). When the seeing is bad, it doesn’t just obscure the details, it obscures the thing itself. Seeing is critical.

City Skyline

I haven’t taken these to Manhattan yet, but I imagine they would be excellent for people watching. We have a nice view of the Atlanta skyline from my office. Here is an estimate of what can be seen:

20x60 vs 7x42 FOV Compare Skyscrapers

Birds, Wildlife, and Mountaineers

My wife and I recently took a trip to Switzerland. In the town of Murren, we had incredible views of some of the highest mountains in Europe. I was scanning the scene with the 20×60’s and stopped to study the top of the Eiger. Then I noticed some tiny little movement. After studying the view for a while I realized I was witnessing some hikers making it to the top. I was able to perceive their victory arms in the air and the colors of their jackets. Undoubtedly I was witnessing an achievement for them as mountaineers, but this was also an achievement for me and my 20×60’s.

From where I was sitting in Murren to where the hikers were standing on the Eiger is 5.8 miles laterally and 1.5 miles up (Murren’s altitude is 5,400 ft and the Eiger’s is 13,000 feet). The hypotenuse of that triangle yields the crow-fly distance between my binos and the hikers which was six miles. Six miles! And I was able to resolve a human figure at that distance. That is incredible.

me-in-murren

Closing Remarks

I have heard some people complain about how heavy these are. I’m no body builder, and they’re not that heavy. I have heard some people complain about finger fatigue from having to hold the stabilizer button down. I’ve never experienced that–I play piano, so maybe I have stronger fingers than the average user? And I have heard complaints about how expensive these are. Ok, this one’s true. I purchased mine used on eBay, but even then I had to sell my AT72 telescope, Manfrotto 475B tripod, Half-Hitch mount, Televue Binoviewer, and set of paired eyepieces. Some people would say I’m crazy for trading in such a wonderful grab-n-go system for these binoculars. But honestly, I’ve never looked back. These binoculars are bad ass. They look and feel awesome. They take up minimal space in my small condo. They fit in my back pack. I can use them to study bison in Yellowstone, waterfalls in Switzerland, people in skyscrapers, or nebulas in Orion. For me, their power and versatility has made the transition worth it. One day I’ll have a stationary observatory so I can get my 200x views of Jupiter back, but until then I am quite content to view the universe in my hands at 20x.

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