The night sky can be frustrating sometimes. You are trying to get a good focus on a distant celebrated celestial object, but the eyepiece you are using just won’t focus properly. It is the wrong magnification. Exasperated, you go and fish around in your bag and grab another one. You detach the original eyepiece and hook up the other one, being careful not to move the telescope too much. When you realign the scope, you realize that the object you were tracking has drifted out of view, and you must restart the whole process of finding and focusing over again.
Anyone who has gone through this song and dance and felt frustration during what should be an exciting and soothing hobby knows how awful this can be. Various eyepieces are part of the rub, and almost every telescope comes with at least two, if not more. There has been an attempt to remedy this inconvenience, and that has come about in the form of zoom eyepieces.
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What is a zoom eyepiece?
Zoom eyepieces are variable telescope accessories that can be adjusted to different magnification on their own. Eyepieces are usually a fixed magnification level because they have a static length and lens. Zoom eyepieces either have multiple lenses within them, or they have a telescoping function to adjust the length of the eyepiece and, therefore, the magnification.
Many zoom eyepieces have a range of magnifications they can accommodate, which means that there is no need to swap between multiple eyepieces during a viewing session. This can cut down on some of those frustrations that eyepiece swapping can cause.
Zoom eyepieces come with a variety of benefits over fixed lenses.
Pros of Zoom Eyepieces
A versatile addition to the telescope toolbox
The most significant upside to zoom eyepieces is that they can do the job of multiple eyepieces in one package. This means that depending on the night, you might never have to swap out an eyepiece during an observation.
A typical backyard astronomer might have three to four different eyepieces at various lengths. These usually come in multiples of four, and each offers a low magnification or a high magnification. With a typical zoom eyepiece, you can get a range, say 8mm to 24mm, that can cover and account for multiple different fixed lenses.
For anyone who enjoys these zoom lenses, they can be used in place of the fixed lenses. This can save a lot of money over time. Instead of buying three, four, or even five different eyepieces over time, you can get one quality zoom eyepiece that will take the place of multiple similarly priced lenses.
This can also save space and confusion. If you like to travel with your telescope as many do, having to take only one single zoom lens with you instead of a back of multiple eyepieces can cut down on the stress. You won’t have to worry so much about losing, breaking, or forgetting any single eyepiece while taking your telescope out and about. You only have to keep track of a single one.
This versatility, both in the backyard and on the road, means fewer disruptions during actual viewing. It can be a drag to have to swap out a lens in the middle of finding an object. This way, you won’t lose that flow and can adjust to the conditions of the night sky as they come about.
An eyepiece like that also increases the ability to be spontaneous while stargazing. With fixed eyepieces, if you are looking around and spot something that looks unique or unknown, sometimes that object cannot be appropriately focused without swapping lenses, and swapping the lens might cause you to lose the new object before you can get a good look at it.
With the zoom eyepiece, it is easy to adjust the magnification level on the fly so that new deep sky objects won’t get lost in the void while fiddling with the telescope. It can increase the joy and wonder in exploring the night sky.
If zoom eyepieces are so versatile and hassle reducing, then why do most telescopes still ship with fixed eyepieces? That is a great question.
Cons of Zoom Eyepieces
Jack of all trades and master of none
If zoom eyepieces sound too good to be true, that is because they are. If they were truly superior to fixed eyepieces, they would have taken over the market and forced out the inferior fixed eyepiece. This has not happened for a variety of reasons.
The versatility of the zoom eyepieces means that they are not optimized for anyone magnification or focal length. This means that they can have some optical quality issues in comparison to their fixed lens brethren.
A fixed eyepiece is specifically designed for a specific magnification level with a specific lens and a single focal length. This means while it might be frustrating to have to swap lenses out, the lenses being swapped are tuned specifically to do that one zoom level exceptionally well.
In contrast, a zoom eyepiece has a variable focal length or multiple lenses in them. This can lead to unwanted reflections and light bending. This is because the lenses are not tuned to a specific focal length and cannot perform at its best.
What this means…
For example, if you adjust the focal length of a zoom eyepiece to a point where an object looks better than it did before. The lens being used had an optimal quality at focal length x, and now the lens is trying to look at something at the focal point Y. This means its working in a way it was not tuned for, and the image quality might not be at peak performance compared to what you could get out of a fixed eyepiece.
They also have a smaller field of view than fixed eyepieces. For the same reasons that optical quality can take a dip in zoom eyepieces, they also see a smaller slice of the sky than a fixed eyepiece. This can be a big downside if you plan on doing long term night viewing.
Keep an object in focus over some time is much harder to do with a smaller field of view than a wider field of view. Therefore, a fixed eyepiece is usually superior when wanting to look at a single object.
Is a Zoom Eyepiece for Me?
While zoom eyepieces are not perfect, they can be a useful addition to any astronomer’s kit. They are versatile, fairly cheap, and can fill a lot of holes in specific circumstances. If the optical drawbacks do not worry you, then they can be very handy.
They are great for the wandering astronomer, the person who wants to take their telescope with them with minimal baggage and enjoys scanning the night sky for neat and unplanned sights. The ability to zoom on the fly without taking your eye off the sky is great for those who want to scan for new and exciting sights.
They can cut down on the costs of multiple expensive eyepieces. You can get away with taking one decent zoom eyepiece with you instead of a bag of fragile eyepieces.
I would not replace my collection of fixed eyepieces with a couple of zoom eyepieces, like many things in the wonderful field of astronomy they serve a purpose and are one of many different tools and accessories that make telescopes such versatile and amazing devices.
Here are three excellent zoom eyepieces that can be great additions to any telescope accessory bag.
Budget Zoom Eyepiece:
Celestron 93230 8-24mm 1.25 Zoom Eyepiece
For the price of a single fixed magnifying lens, you can get the Celestron 93230 8-24mm 1.25 Zoom Eyepiece. This zoom eyepiece can fluidly go from the zoom of an 8mm eyepiece to that of a 24mm eyepiece without taking your gaze from the telescope.
This is a large range of magnifications that come in this eyepiece, making it a great accessory for the versatility alone. It can comfortably take the place of three or four fixed eyepieces in terms of magnification, meaning much less swapping and less hassle when taking accessories around.
From the reliable makers at Celestron, this zoom eyepiece comes with multicoated lenses and a folding eyecup. It is light and is made to fit any 1.25” compatible telescope.
However, the wide range of zoom levels in one eyepiece means that it does none of them particularly well, and it does not fit all telescope eyepiece mounts. For the money, it is a good zoom eyepiece that can do a lot for a little. It is universally well-reviewed and can be an excellent tool for any backyard astronomer.Check Latest Price
Mid-Priced Zoom Eyepiece:
Orion 8-24mm Pro Lanthanum Zoom Eyepiece
For a good chunk more, the Orion 8-24mm Pro Lanthanum Zoom Eyepiece offers some excellent quality upgrades over the budget version of the 8mm to 24mm zoom eyepiece.
This eyepiece just oozes quality in design. It comes with a large zoom adjustment zone, which is covered in a textured rubber grip that is pleasing to both the eye and your fingertips. This rubber grip also doubles as a waterproof coating so the eyepiece can stand up to a little weather.
It also comes with a super cool parfocal zoom feature, which keeps the eyepiece focused as you change the magnification. This means no refocusing required as you switch zooms on the fly. This truly feels more like using a good pair of binoculars over a telescope. The ease of magnification adjustment and refocusing is genuinely outstanding.
Minus the automatic focusing, which is an awesome feature, the performance of this eyepiece is very similar to the Celestron one. If the quality of life upgrades in terms of grip, focusing, waterproofing, and looks are important to you, then the upgrade in price is definitely worth the money for this one.Check Latest Price
High-End Zoom Eyepiece:
Baader Hyperion Universal Mark IV Zoom Eyepiece
If versatility is what draws you to the zoom eyepieces, the Baader Hyperion Universal Mark IV Zoom Eyepiece is the pinnacle. This eyepiece includes five magnification levels that are easy to swap between without removing it.
It comes with an easy swap between 8mm, 12mm, 16mm, 20mm, and 24mm focal lengths. All of the standards included in one eyepiece.
Unlike the competition, the Baader Hyperion Universal Mark IV Zoom Eyepiece is truly universal. They have made it so that this eyepiece can truly take the place of any other eyepieces you might have lying around.
It comes with multiple kinds of eyecups for different users. A folding eyecup, winged eyecup, and a straight eyecup mean that this eyepiece can be used with almost anything—people with glasses, a Barrows magnifier, and even cameras for astrophotography.
On top of this, it comes with a changeable barrel, which makes it compatible with both 1.25″ and 2″ telescopes. This makes it truly universal. While the other eyepieces on this list can only be fitted with 1.25″ telescopes, this one can do both of the most common sizes. This eyepiece can be taken and used with any telescope in almost any situation.
You will never be caught flatfooted if the Baader Hyperion Universal Mark IV Zoom Eyepiece is in your accessory bag. The versatility and universal nature of this eyepiece mean that it truly has no weak spots. If the budget can absorb the price, this eyepiece can cover a lot of gaps and come in handy in almost any situation.Check Latest Price
Though they have their drawbacks, zoom eyepieces are neat and useful telescope accessories. They can be bought at a discount to cover the cost of multiple fixed lenses while just getting started, or you can drop a decent sum on high-quality versatility and get an eyepiece that can be used in almost any situation.
Whatever the case may be, these are three of the Best Telescope Zoom Eyepieces that should catch the eye of any amateur astronomer. They can just kit out any telescope set up and make for fluid and easy viewing of the vastly explorable night sky.