Do you have an old pair of binoculars? What can you do with them?

Many people have an old pair of binoculars in the back of a cupboard or in a bottom drawer. As the weather warms, it’s a perfect time for some nature viewing or heading off to the sports, but do you know that almost *any* pair of binoculars can be used for astronomy? While BINTEL sells specialised astronomy binoculars, you can get started with your existing pair.

The reason why binoculars are popular with astronomers is they have a wide field of view, and this lets you observe some of the more expansive parts of the night sky.  They’re ideal for viewing:

  • The Moon
  • The star clouds in the Milky Way
  • Our largest satellite galaxies, the Large and Small Magellanic clouds
  • Large nebulae, like the Orion Nebula or Eta Carina
  • Plus more!

Binoculars are not ideal for planetary viewing as they don’t have the magnification needed to see finer details like the rings of Saturn or bands across Jupiter, although you might be able to see the four moons of Jupiter spreading out either side of the planet.

And old pair of Swarovski binoculars

Cleaning binocular optics

It’s pretty common for binoculars to become dirty with all sorts of stains through use, but they can also suffer from mould or fungus if left unused for long periods of time. This happens to optical surfaces of all sorts, including telescopes, camera lenses and microscopes. There’s a bunch of microbial bugs who seem to really enjoy munching on the coatings applied to lenses!

The best way to help a pair of old binoculars back into service is to clean the optics, especially if they’re misty or cloudy. If there’s a few specs of dirt of dust, don’t worry about them too much. They might be annoying, but the amount of light blocked will be minimal.

There are two sets of surfaces on binoculars that need cleaning. The front or binocular objective and the eyepiece side where you look through. It’s important to clean both ends are they’re both equally important.

The first step is to remove any dust or dirt on the glass surfaces.  If you rub these to clean them off, you run the risk of creating tiny scratches on the lenses.  Instead, blow the dust and dirt off using a commonly available air blower. You can pick these up at large department stores or camera shops.

A better option is to use compressed air in a can. They’re also called “air dusters” and you buy these for a few dollars at places like Bunnings. If you have an air compressor DO NOT use this. They can spray small amounts of oil on the glass surfaces.  You can also use fine dusting brush to remove particles.

Once you’ve removed the dust and dirt, it’s time to move on to cleaning any stains, oils, finger prints or mould/fungus off the optics.

Two points:

  • If your binoculars have lived mainly in the city, they will be dirtier than a pair that have spent their time in the country. There are more particulates in the city air due to air pollution.
  • You should take care when cleaning mould or fungus off binoculars by doing so in a well-ventilated area, but this is not usually the “black mould” found in premises that is a major health concern.

To clean optics, we suggest using a cleaning solution and plain, unscented tissues. We would highly recommend using the BINTEL Cleaning Solution or similar:

Another option that is not as effective would be commonly available plain WINDEX. Dilute it 50/50 with distilled water. Full strength glass cleaner can leave streaks.

Apply a few drops to a plain tissue. The tissue needs to be just damp, not soggy or saturated. Crumple the tissue and then gently wipe it across the optical glass. Don’t scrub or apply pressure. You’ll need to do this several times until you’ve cleaned stains off the glass. When this is done, take a dry tissue and dry off any remaining cleaning fluid.

Take your time! Cleaning optical glass surfaces is slow and gentle work – not hard work. You might be surprised at how clear the views through your binoculars are once they’ve been cleaned.

What if the cloudiness is on the inside of the binoculars? This is a problem. It means that mould has made its way into the body of the binoculars. The only way to clean them is to take them apart. Dismantling binoculars is a tricky process and needs to be done in a workshop.


Another fault that old binoculars might have is poor collimation.

You might have heard about collimating telescopes. This is where a telescope’s optics are re-aligned to make sure they produce the sharpest image possible. Some telescopes need frequent collimation, especially after travelling. A good example of this are Newtonian style reflectors. In most cases, collimation is a fairly simple process that only takes a few minutes. (We have a recording of a full workshop on telescope collimation at the BINTEL YouTube channel which can be found here. )

Binoculars are collimated in the factory as part of the manufacturing process.  The primary collimation is to make sure that the two barrels side by side are perfectly in parallel with each. There are also other elements in both roof prism or porro prism style binoculars that need to be aligned to produce other a clear image. Unlike telescopes, binoculars are not designed to be re-collimated by their owners. However, they can also go out of collimation. In almost all cases this is due to them receiving some sort of physical damage, often from being dropped on a hard surface.  It might not show on the outside, but the alignment of the optics might be damaged.

What’s the easiest way to know your binoculars are out of collimation? – You have a headache or eyestrain after using them for even a short period of time! They might also show “double images” when looking through them.

Re-collimating binoculars is best left to an optical repair workshop. Please note we do not collimate binoculars at BINTEL. There are a number of “how to” guides on re-collimating binoculars on the web and YouTube. We strongly suggest that the chance of further harming your binoculars by trying such material yourself is very high!

If your binoculars are out of collimation you can still use them by simply looking through just one side. Either keep one eye closed, or hold them at an angle so only one side is up to your face.

Mechanical problems and worn bodies. 

Again, due to their complexity, repairing broken focus wheels or fixing the bodies of binoculars are best left to the experts.  The same cleaning process that is used to clean optical surfaces can also be used to clean binocular bodies. Avoid harsh cleaning sprays, especially on rubber coated bodies.

Restoring an old pair of binoculars.

If you have an old pair of binoculars that has sentimental value – and for some reason binoculars especially seem to a link to previous generations for many families – there only a handful of companies that can do this.  One place we always recommend is Optical Repairs. Contact them on the web here or call them on 07 3715 5603.


The old pair of binoculars you’ve had for many years might have some new life breathed into them with a careful clean. Take your time and head out to enjoy the spring weather and the night sky above us!


Earl White


20th Oct 2023




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