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Celestron Zoom Eyepiece Review – 8mm to 24mm Focal Length

Zoom eyepieces are adjustable to cover a range of focal lengths. In this way, they let you enjoy different magnifications without needing to swap eyepieces.

In our Celestron 1.25″ Zoom Eyepiece review, you’ll find that this model is no exception. Its focal length ranges from 8mm to 24mm and, in addition, the body is marked for 12mm and 18mm stops.

See our complete guide to zoom eyepieces

To make the math easy, assume we have a telescope of 960mm focal length. Used in that telescope, this zoom eyepiece (EP) will take you smoothly from 40x to 120x magnification.

Using it is as simple as finding a celestial object and twisting the barrel to zoom in or out.

Celestron’s Zoom Eyepiece

Thanks to Rother Valley Optics* for their generosity in loaning the model used in this review and our video review.

Celestron Zoom Eyepiece Specifications

The apparent field of view on this model varies between 40° and 60°, depending on the focal length is selected. The longer the focal length, the wider the field of view.

Eye relief varies between 15mm and 18mm and is perfectly comfortable. There is a deep rubber eyecup attached to the EP, making it easy to achieve a comfortable viewing position. As you’d expect, the cup is retractable for wearers of spectacles.

The levels of magnification and fields of view make it a suitable EP for both solar system and deep space object observations.

Reduced
Celestron - Zoom Eyepiece for Telescope -...
  • Zoom from low to high power in an instant with this versatile eyepiece!
  • Compatible with any telescope that accepts 1.25 eyepieces
  • This fully multi-coated Premium eyepiece zooms to any focal length between 8 mm and 24 mm - pick the best magnification for your subject

The Zoom Eyepiece in Use

I used the Celestron over two nights of observing. The first had hazy cloud, but I managed to enjoy Venus and the Pleiades before the cloud got too thick for any more observations.

The sky on the second night was crystal clear, and I’d also had opportunity to collimate my telescope before use. On that evening I studied the Trapezium in Orion and hunted some double stars in the same constellation.

Optical Quality

I was pleasantly surprised to find the optics of a very high quality.

The focus on stars was pin-sharp and bright. I could see a little bit of coma on the stars at the edge of the field, but had to pay particular attention to notice it, and it was in no way distracting.

Venus was distant and small on the night I observed, and the zoom didn’t do much for me, although I did see the crescent. I would have liked the opportunity to see Jupiter with it, but it was not to be.

It’s a completely different story when it comes to the Pleiades.

They were absolutely glorious jewels of light at the lowest magnification and largest field of view. As I zoomed in, shortening the focal length, more and more stars appeared in the eyepiece. All the while clarity was maintained, even as luminosity came into view.

Pleiades
Pleiades with nebulosity showing (source)

Spying the Trapezium was just as rewarding.

Presented with a large field of view of the Orion nebula, the Trapezium was a small patch of just-about-distinguishable stars. As I zoomed in the gaps between the stars became larger and the trapezium almost filled the field of view at the greatest magnification.

Sadly, conditions weren’t good enough for me to pick out the dimmest members but, nevertheless, it was a spectacular sight.

The most fun of the evening came in hunting double stars in Orion.

There are a number of them scattered around this favorite constellation and the zoom eyepiece worked a treat on them. At the lowest magnifications I rarely saw the companion star, but I marvelled as they came into view with a twist of the barrel.

A few were ghostly and dim, but the optics did wonderful work of making them visible on a less than ideal evening.

Pros and Cons of the Celestron Zoom Eyepiece

I’m actually going to start with the cons because there aren’t that many of them and they are hugely outweighed by the pros!

The biggest issue I had was the lack of a click-stop telling me when I had a particular focal length selected. On the barrel of the EP are clear markings for 8mm, 12mm, 18mm and 24mm focal lengths, but the transition between them is completely smooth.

On the face of it this sounds like a good thing. However, when I was transfixed at the eyepiece it would have been very helpful to have a little click when I reached one of the standard focal lengths.

This feature is found in other zoom eyepieces and would make this one just about perfect.

Use this eyepiece with our top telescope models of 2020

It’s hard to say that my next comments are genuine cons because they are more a side-effect of physics.

Zoom eyepieces have more glass in them than a dedicated, single focal length eyepiece. This makes the view through them dimmer, but I did not find this was noticeably so.

In a similar vein, the process of zooming in noticeably darkens the field. This is most definitely down to physics, but something you should be aware of.

Finally, one other factor to note is that the various focal lengths contained within this EP are not parfocal. This means you have to adjust your telescope’s focus every time you twist the barrel of the eyepiece to increase or decrease magnification.

This was sometimes frustrating, but certainly no more so than changing between eyepieces… which nicely brings me to the pro’s of Celestron’s zoom eyepiece.

Focal length marking on the celestron zoom EP
Focal length markings on the barrel

One of the upsides I’ve already covered, which is the fantastic clarity of the optics. Seeing stars pop into existence at high magnifications at the twist of a barrel is a wonderful experience.

The biggest benefit of all, however, is the improved flow which having a zoom eyepiece brings to an evening’s astronomy.

My experience with this piece of equipment, and its impact on my enjoyment of the evening’s viewing, cannot be overstated.

For the price of one or two regular eyepieces, this zoom eyepiece provided the equivalent of four individual EPs. But, more than that, it allowed me to keep looking at a particular celestial object and increase or decrease the magnification without having to change eyepiece.

The flow which this brought to my viewing, because I was not having to fumble around and risk losing my dark adaptation in swapping over eyepieces, was immeasurable. I just spent more of my time with my eye at the telescope.

Changing magnification at will meant the object I was looking at stayed centered; I did not lose concentration and time to transitioning between EPs. And, if I didn’t like the view, or the magnification was too high, it took no time at all to dial back to an agreeable image.

This improved, more relaxed method of observing, coupled with the high quality optics, means that I have no hesitation in heartily recommending this Celestron zoom eyepiece.

looking down the barrel of Celestron zoom eyepiece
Looking down the barrel of the Celestron zoom eyepiece

Summary

The Celestron 8mm-24mm zoom EP retails for around $80. You can see today’s price by clicking this link.

When you consider that what you’re actually getting is the equivalent of four individual eyepieces with high quality optics, this cost is a steal.

Now, it doesn’t meet all needs. It does not have a massive field of view, nor does it deliver very high magnification. So, you may still want to bolster your collection with EPs to meet those needs (like this one).

This zoom delivers huge benefits though. Being able to find an object at low magnification in a large field and then zoom into it, without having to change eyepieces, brings a whole new level of enjoyment to astronomy.

For that reason alone, I am very happy to recommend the Celestron zoom eyepiece to every backyard astronomer.

Click here to buy yours now.

If you’d like a little more insight into my thoughts on this model, watch my full video review below.

Celestron Zoom Eyepiece Video Review


Rother Valley Optics is a renowned UK-based optical retailer. They sell a massive range of astronomy products from filters to telescopes and, with over 12 years’ trading experience, pride themselves on their honest, useful advice.

My thanks to them for the equipment loan. Check them out for yourself here.


*Rother Valley Optics neither sponsor nor have editorial control over this post. We do not receive any commission payments from RVO.

Last update on 2020-03-20 / Affiliate links / Images from Amazon Product Advertising API