Zooms: Cheap is OK, but wider is better

Does a cheap Celestron zoom eyepiece compare well with one that gets good reviews and sells for two or three times the price? Yes. but a new, wider zooms appeals t me as well.

But before going into that, let me say that for my personal use – and my use in public programs – I'm convinced that zoom eyepieces are a good and useful tool. They have received a lot of criticism in the past – and it may be well deserved – but what I am looking at – and looking through – are a pleasure to use. No, they are not quite up to the standard of a dedicated eyepiece and at low powers offer comparatively narrow field – but the simple advantage of having one eyepiece and zooming it outweighs these faults in many observing situations.

Now the question is, which zoom? First, the zooms don’t get that many reviews because serious amateur astronomers seem to not take them seriously. But in the reviews I have seen the Vixen 8-25mm zoom seems to get the highest marks. These have typically sold for $190, I advertised for one on Astromart and got it for $115 a couple weeks ago. Sounded like a good deal. But in the interim a better deal has come and gone. Vixen has been running a wholesale sellout that I wasn't aware of and they sold their stock – their stock in America – of these zooms for $128 each. All are gone now.

Meanwhile at Optics Planet (and elsewhere) a Celestron Zoom that looks very similar has put in an appearance at a very reasonable $63 - and that includes shipping. Satisfied with my Vixen, I ordered one of these and it arrived yesterday. Last night I tested it in a ShortTube 80. I tried the Moon, Saturn, and Mizar and in each case I simply couldn’t see much to choose from between the Celestron and the Vixen.

Now I don’t have a clue if these are both made in the same factory – or have any relationship to one another. The Celestron I have has a slightly gritty feeling to the mechanical side of things when you turn the zoom – but it's mild and does not seem to impact use. As I switched back and forth, this was the only way I could readily tell in the dark which one I was using. Looking through them didn’t tell me anything. I saw more internal reflections than I like to see – but I switched to some Plossls of similar magnification and they showed the same thing, so I have to think the problem there is with the scope.

They look a little different and when I put them on the scale theVixen7.4 ounces and the Celestron 8.3. Why? I don't have a clue.

Bottom line – I would not hesitate to recommend the Celestron. Great price for an eyepiece that could become the one you use the most.

Meanwhile, the folks at Baader Planetarium have me thinking because they have a reputation for producing good products and their Hyperion line gets positive reviews. They are offering a new zoom that takes a big step toward alleviating the field of view issue. Take a look at the specs on the Celestron, then the new Hyperion. and pay particular attention to the afov specification.

Eyepiece is Fully Multicoated.

Specifications for 1 1/4-inch Celestron Zoom Eyepiece 93230:

Focal length: 8mm - 24mm
Field of view: 40 – 60 degrees
Eye relief: 15 - 18mm
Optics Coatings: Fully Multicoated

Baader Planetarium - 8-24mm Hyperion Clickstop Zoom Eyepiece

* This Baader Hyperion 8-24mm Zoom eyepiece has click-stops at 8, 12, 16, 20, and 24mm and remains parfocal across the zoom range.

* Perfect for binoviewing, as long as your binoviewer can handle barrel diameters of 57mm.

* Field of view ranges from 50º to 68º...not bad for a zoom eyepiece!

* Eye relief is really nice (between 12-15mm, depending on the magnification).

What's the extra fov really translate to? Take a look at these images taken from Starry Nights software. They both show the true field of view when these eyepieces are used in my Orion 80 ED. The first shows a comparison at highest power on the cluster M35 – the second at lowest power on M45, the Pleiades. (Click image to enlarge.)

Not a great big difference, is it?

But, what's the intended use? The main personal use I have for the zoom is in my 80Ed – or similar scope – ounted on the parallelogram mount. In this situation there is no clock drive, so having more field – with no sacrifice in power – is important, even if there's a significant drop in quality of the image at the edges of the field, having a wider fov just means fewer adjustments to the scope, and that means less time waiting for the scope to settle down. It also make it simpler to find things and to keep them in view once you have found them.

So I'm thinking very seriously about the Hyperion. Stay tuned!