SI-TEX Sirius 12 stabilized binoculars, stability at a nice price

Within a few months of leaving to travel America’s Great Loop, I decided there were two things my boat was sorely lacking. The first was a set of wireless headsets or marriage savers — rarely has a product been so accurately named. The second tool I found myself lacking was a pair of stabilized binoculars. A few nausea inducing episodes of trying to read the transom of a moving boat from the pitching deck of Have Another Day convinced me of the utility. While the marriage savers were quite affordable, the stabilized binoculars left a larger dent in my wallet. So, I was quite pleased to have the opportunity to try out SI-TEX’s Sirius stabilized binoculars and their much more affordable cost of entry.

Specs and pricing

The SI-TEX Sirius 12 binoculars carry a 12×21 rating. That means they offer 12x magnification and an objective lens effective diameter of 21mm. The binoculars run on just one AAA battery for up to 12 hours. The binoculars measure 4.7 by 5.2 by 2 inches. Weighing in at 438 grams or just under one pound, these are among the smallest and lightest stabilized binoculars I’ve come across. The toggle switch on top of the binoculars turns stabilization on and off. If you forget to flip them off, they automatically turn off after 30 minutes to conserve battery. The Sirius 12 retails for $699 with a carry case, strap, two sets of eye cups, and neoprene glare shield.

Just for a little comparison, while travelling on the Great Loop, I bought a pair of Nikon StabilEyes 14×40 binoculars. I found a big special from Defender on a refurbished pair. Suffice it to say, at $699, the SI-TEX pair is a bargain. Comparing the two pairs is a little tough, the Nikon offer an additional two power of magnification and with their 40mm lens diameter they admit more light. That additional light admittance means the Nikon image is brighter and easier to see in low light. However, that brightness and magnification comes at the cost of size and weight. The Nikons are a little bigger at 7.3 by 5.8 by 3.5 inches. But at 1,340 grams or three pounds, they’re more than triple the weight! That weight difference is before adding four AA batteries compared to the one AAA for the SI-TEX.

On the water with Sirius

Last summer, my wife and I took a trip to Croatia and chartered a boat with two other couples. Among the six of us, four held various USCG captains licenses, we’d each completed the Great Loop at least once, and all six of us have lived aboard boats for years. I brought a handful of portable test gear to try out during our charter. The Sirius 12 quickly became the most highly used piece of equipment I brought. The binoculars lived just inside the forward door of our sailing cat and saw action dozens of time a day.

The binoculars primarily saw use during daylight hours. I found the image to be plenty bright and impressively stable. These are pretty small in your hand with a pretty high magnification power. Without the stabilization, especially on the deck of a moving boat, it would be very difficult if not impossible to keep them stable. In fact, if you pick them up quickly without turning on stabilization, it only takes a second looking through them to be reminded it’s off.

If you haven’t had the opportunity to use stabilized binoculars, you might be wondering about their utility and weather they’re worth the expense. Allow me to cast a resounding yes vote. Stabilized binoculars make seeing the names of boats, numbers on aids to navigation, clearance boards, bridge names, and so many other things on the water vastly easier. In a highly unscientific guess, I estimate that I can read these details about twice as far with stabilized binoculars as unstabilized. Additionally, stabilized binoculars make higher magnifications usable. 12 and 14 times magnification is very difficult to hold still; but add stabilization and it becomes a piece of cake.

Sadly, my Nikon StabilEyes were on Have Another Day during hurricane Ian. I rescued them and cleaned them up, but the electronics have not recovered. So, I am not able to directly compare. However, my recollection is that the StabilEyes had slightly more agressive stabilization. Especially with the additional magnification, that makes sense. However, I find the Sirius’ stabilization to be effective and useful. Plus, I imagine more stabilization would mean less battery life and more batteries required. The compact package of the Sirius 12 is one its greatest attributes.

The Sirius 12 collected heaps of praise for their high power, easy use, and stable view. The one consistent complaint I heard came down to the relatively small visual target as you look through the binoculars. The result is that if your eyes are not well aligned in the eyepieces, the image is either cut off or you see all black. Some research reveals that the exit pupil describes the size of the image in the eyepiece. Exit pupil size is a function of the objective lens diameter divided by the binocular’s magnification power. The Sirius 12 have 21mm objective lenses and a 12x magnification. That yields an exit pupil of 1.75mm. In comparison, the 14×40 Nikon StabilEyes have an exit pupil of 2.85mm or 63-percent larger. So, at the end of the day, their biggest downside is simply a matter of physics. For the exit pupil to be larger, the objective lenses would have to be larger, which would make the binoculars larger, heavier, and more expensive.

Final thoughts

For my current use, on smaller boats and sometimes moving from boat to boat, the SI-TEX Sirius 12 represent a nearly perfect compromise. They are small, relatively affordable, offer strong magnification and effective stabilization. I’m not sure what else one could ask for from them. In a larger pilothouse, I might prefer a larger set of binoculars with larger optics to allow a little more light in, but even then, I’m not sure the extra weight would be worth it. If you’re looking for something to make reading boat names, clearance boards, markers, and other features on the water easier to read, the SI-TEX Sirius 12 fit the bill quite nicely.