Nov
5
James Mackay has kindly submitted his review of the new Baader 8-24 Hyperion Zoom eyepiece :
Faced with limited space in the family car when we go camping and the inevitable “Why don’t we leave the scope behind?” question I decided it was time to rationalise my collection of eyepieces. I have a case full of them (some good, some bad). Then I came across the Baader Hyperion Zoom eyepiece at the South West Astronomy Fair in August.
The Baader Hyperion Zoom eyepiece has a focal length range of 24mm down to 8mm with stops at 24, 20, 16, 12 and 8mm so potentially could cover most of my observing needs. Steve was kind enough to loan me one to test and to compare with my other eyepieces.
Up against
24mm & 15mm Televue Panoptic
21mm & 8mm Baader Hyperion
20mm Televue Plossl
16mm Nagler T5
10mm Pentax XW
All the above are very good and capable performers, several are arguably the best on the market at their focal lengths. The Baader Zoom will have to perform well if it is to rub shoulders with the others!
Baader Hyperion Zoom (middle) with 24mm Televue Panoptic (left) and 8mm Baader Hyperion eyepiece (right)
Used with
Celestron C10N 10″ f/4.7 Newtonian (a tough test for any eyepiece!).
Skywatcher Evostar 120 4.75″ f/8.3 Achromatic refractor.
Meade 4.5″ f/8 reflector.
Looking for
Correction of optical issues such as astigmatism, spherical aberration and field curvature.
Clarity and sharpness of image to the edge of the field of view.
Eye relief/comfort of use.
Apparent field of view.
It’s performance compared to fixed focal length Hyperions.
Other issues such as kidney beaning.
First impressions
First impressions at the SW Astronomy Fair on opening a new Hyperion Zoom were good. The eyepiece fairly reeks of quality! Like other Baader eyepieces it is packed well, comes with a leather pouch, is solidly built and just a little heavier than a standalone Hyperion. The zoom mechanism is firm but smooth with positive click stops. The action enables you to quite easily set focal lengths between the click-stop settings so that most focal lengths between 24 and 8mm are available. The click-stops are also conveniently labelled upside-down relative to the brand name for ease of reading when attached to the telescope focuser.
Performance
I first used the Zoom in a Coronado PST solar telescope and was able to focus on the Sun at the 24mm setting and then zoom down through 20mm, 16mm, 12mm to 8mm. A slight refocus was needed at 12mm. The apparent field of view starts off at 50 degrees at 24mm and increases as you zoom through the focal lengths ending at a respectable 68 degrees at 8mm. The ability to smoothly ‘zoom in’ was attractive - I couldn’t wait to try it on a star cluster or globular…
The tough test - 10” f/4.7 Newtonian
Baader 8-24 Hyperion Zoom fitted to Moonlite focuser on a Celestron C10N
I got a chance to spend a night recently at a dark(ish) site with the Zoom eyepiece and my 10” reflector. This scope’s fast focal ratio is a tough test for any eyepiece as it has to deal with a steep light cone and the zoom was up against my usual eyepieces for this scope: 24mm Panoptic, 16mm Nagler and a 10mm Pentax, all of which are considerably more expensive and well corrected at this focal ratio. For comparison I also used two Hyperions (21mm and 8mm). The scope was well collimated using a Catseye autocollimator and had been cooling down for about ninety minutes.
Its worth noting that the Panoptics/Naglers/Pentax are all excellent performers (the Panoptics and Nagler show the merest hint of astigmatism) which is only to be expected considering their price, and all are significantly more expensive than the Baader Hyperion Zoom.
Starting with objects near the zenith I looked at M13 & M92 in Hercules, some open clusters in Cassiopeia and at some dense star fields in the Milky Way. The Zooms field of view at the 24mm setting is 50 degrees, a restriction that is quite noticeable to anyone used to wide field eyepieces, but a more narrow field of view can be forgiven if the image quality is good.
The view at the 24mm setting was somewhat disappointing. There were aberrations visible in the outer 25% of the field of view and the effect was a little like looking down a tunnel with the sides being a little blurred. There appeared to be both field curvature (stars focused at the middle needed refocusing in the outer 20% of the FOV) and astigmatism (moving each side of focus revealed aberrations that flipped 90 degrees) with the field curvature being the more pronounced. The view on axis was good and clear but I was a little disappointed that good image correction wasn’t maintained across the whole of the 50 degree field of view, after all 50 degrees isn’t particularly wide.
Somewhat apprehensively I flipped down through the zoom settings which revealed that a slight refocus is needed at each click stop, just a slight tweak. The quality of view improved through the click stops with the aberrations decreasing steadily until the 8mm setting where the view was really rather good. At 8mm the apparent field of view widens to 68 degrees. This leads to a little disorientation as I’m used to low power wide-field eyepieces and narrower fields for higher power.
Visual aberrations at the 8mm setting were limited to the last 5-10% of the 68 degree field of view and they were only noticeable when I made an effort to look for them. The view was good enough for me to fit the 8mm Hyperion for a comparison. The Zoom was every bit as good as the standalone 8mm eyepiece, which I rate as being a very good performer. Moving back through the focal lengths to 24mm the aberrations gradually worsen until they impinge on my enjoyment of the view at around the 16mm setting.
In fairness, the aberrations are not severe except perhaps at the 24mm setting. Many observers will not notice them or care what happens at the edge of the field and I am comparing the Zoom with some exceptional eyepieces.
I spent the next hour or three just looking at different targets through the Baader Zoom. As the majority of targets were in the zenith area I barely needed to move. I also didn’t need to change my eyepiece at all! There was no fiddling with switching eyepieces in the dark, no major refocusing, no dropped lens caps, just an occasional twist of the eyepiece and the range of magnifications provided (50x - 150x) were fine for the vast majority of targets.
I did find however that I tended not to use the 24mm position due to the aberrations, stopping at 20mm. The magnification difference between 20mm and 24mm (60x v 50x) is pretty small and the true field of view covered is very similar.
The eye relief for the eyepiece was comfortable, my neighbour and observing companion reported the eyepiece was easy to use with glasses. The zoom has a twist-up eye cup that extends out a centimetre or so which helps nicely with positioning the eye. I noticed no major eye placement issues with the eye cup extended and little or no blackout or kidney-beaning, even when observing the Moon.
So, all things considered, a successful observing session with a level of convenience I wasn’t used to. Being able to simply and quickly alter the magnification with only a minor refocus rather than fumbling in my eyepiece case, removing one eyepiece, capping it and putting in the new one is quite something.
The easier test - Skywatcher Evostar 120 f/8.3 refractor (achromatic)
The next night I set about testing the eyepiece in my refractor. I expected an improvement in overall performance compared to the f/4.7 reflector and I wasn’t disappointed. The aberrations were still present at the edge of the field of view at the 20 & 24mm settings but were considerably reduced. The astigmatism remained but the field curvature was reduced somewhat with problems residing in the last 15% or so of the FOV. Whilst the edge performance was clearly enhanced when fitted to he f/8.3 refractor, the on-axis view, or central area, was hard to compare due to the vastly greater light gathering and resolution capability of the Newtonian’s 10” aperture. In both scopes the centre of the field of view is sharp and clear. Once again the problems, although reduced, were most noticeable in the higher focal lengths.
The performance of the 8mm setting was still an easy match for the regular 8mm Hyperion and the overall performance moved closer to that of my other eyepieces.
One issue that did occur was a problem with turning the Zoom between clicks. In my diagonal the compression ring screw had to be tightened quite hard to grip the eyepice firmly enough for me to change the Zoom without it rotating. This is more an issue with the diagonal than a flaw with the Zoom as I prefer the firmness provided by the eyepiece at each click stop.
Another easy test? A Meade 4.5” f/8 Reflector
I was also able to use the Zoom eyepiece in my neighbours reflector. His telescope has a higher focal ratio than my Newtonian and I was keen to see if this improved the performance of the Zoom eyepiece. We collimated the scope and started using the eyepiece… and yes, the performance is improved in much the same way as it was when fitted to my f/8.3 refractor with similar results regards aberrations and field curvature. Overall, the Zoom performs very well in this telescope.
Conclusions… the subjective bit…
Many of the issues mentioned, particularly the quality of views at the higher focal length settings, are personal and subjective. For the purposes of reviewing the Zoom I’ve actively looked for problems, I’ve compared it to several excellent eyepieces and I’ve used a low focal ratio telescope which is a hard test for any eyepiece to face.
Many observers aren’t at all bothered by what happens at the edges of the field of view. Similarly, many will have higher focal ratio telescopes such as a Schmidt-Cassegrain or Maksutov so, if the difference in performance between my f/4.7 scope and f/8.3 is anything to go by, they might not see any of the aberrations I’ve mentioned
In my opinion the Zoom has performed well. The simplicity and convenience of being able to use just one eyepiece is a fair compensation for my disappointment at the view seen at 24mm in my fast scope. The Zoom is in effect five eyepieces in one (more if you choose to stop between the click stops) yet it costs about the same as two regular Hyperions and if you were to build a set of Hyperions to cover the range offered by the zoom, you would be spending over £400. Though to be fair, the longer focal length models would offer better performance.
So, is the Zoom a match for Panoptics/Naglers/Pentaxes? No, it isn’t and nor does it pretend to be. Any one of those eyepieces cost significantly more. If as an observer you are seeking the very best views (and I’m a little like that) and you can afford it then stick to high-end eyepieces single focal length eyepieces. But, if you’re looking for convenience, value for money and very good performance in higher focal ratio scopes, and reasonable performance with lower focal ratios, then the Baader Zoom deserves your consideration.
Pros
Convenience of having one, mostly parfocal, eyepiece to cover a wide range of magnifications.
Good quality views. Reasonable even in fast focal ratio scopes at the lower focal lengths.
Good price - same as two regular Hyperions and less than half the cost of buying a number of them to cover 8-24mm.
Cons
Limited field of view (50 degrees) at the 24mm setting.
24mm click stop seems superfluous given that the apparent field of view is relatively narrow and the 20mm setting offers a similar true field of view.
Aberrations visible at higher focal length settings especially at 20 & 24mm in fast scopes.
Ultimately
A major indicator with any kit loaned for testing is whether the tester returns the kit afterwards. Well, Steve isn’t getting this one back!
The Baader Hyperion Zoom delivers ‘good enough’ views in my 10” Newtonian and very good views in scopes with longer focal ratios. It is also much more convenient than using a number of single focal length eyepieces, so its definitely a keeper!
——
James Mackay - Oct 07
That pretty much confirms my view of the Hyperion zoom James. A lot of field curvature in fast scopes at the lower mag settings but great in slower scopes.
Great review James,
I agree, the Hyperion Zoom works great in my f/10 SCT, but I wouldn’t like to see it at f/5.
Great review, although a pity there is no comparison with Vixen/TeleVue 8-24 zoom (now I have a problem of choice between Hyperion and Vixen)