Stratosphere 2" 42mm 58 degree super-wide Eyepiece

Olivon is probably a fairly new name for most amateur astronomers. They are based out of Richmond in British Columbia and refer to themselves as “a manufacturer based company”; specifically they call themselves the “North American branch of the sales department” They specialize in importing optics from the far east, and have been manufacturing OEM items in their own production facilities for years.

But direct sales are new to them.

They contacted me in late fall about reviewing some of their eyepieces and accessories, and sent their Stratosphere eyepieces shortly there after.

These are a rather unique eyepiece – I’ve only seen them resold under one or two other brand names, and frankly after looking at their performance – that surprises me a bit. But I’m getting a little ahead of myself here.

Initial Impressions

First lets take a look at the eyepieces themselves. There are three in the Stratosphere line up: a 28mm, a 35mm and a 42mm. Physically they are fairly impressive eyepieces – as most 2” ers tend to be - but even here these are a little different. They are rather lightweight for their appearances. I was quite curious about the optical design of these items and penned Olivon directly, but received

multiple answers. Evidently the sales arm and the factory arm aren’t the same arm. In the end, apparently we settled on a three element modified kellner design. I say apparently, because frankly, I’m still not positive,and it does not behave like I would expect a kellner to – but mayhap that’s the modified part. The 28mm weighs in at 11oz, the 35 at 13.3, and the 42 at 15.2 – so it’s pretty unlikely that these would cause a serious balance problem in any of your setups – a definite plus if you are a dob user.

The stated AFOV is 58 deg, a bit wider than a standard plossl, and fits in with the 2” design, as 32mm at 50 deg afov (typically) gives you about the maximum true field of view for a 1.25” barrel.

The Stratosphere’s are well constructed, with a good fit and finish – the eyecup is a design similar to that found on the Pentax XL’s and XW’s – but the rubber is quite a bit softer, and there is no sign of the grease you find on some eyepieces with this type of adjustable cup.   These are certainly as good as some of the offerings we’ve seen from other companies lately – however, I wouldn’t put them up with Tele Vue, Pentax, or even Orion’s standards. Don’t look for any engraving here – there’s not even a name. They only boast a sticker that says “multi-coated” and has the focal length.

The field element in the 40 was definately larger than that in the 35, but curiously both had field stops of around 40mm, while the field stop on the 28 measured about 27.5mm. The field lens was set progressivly further back in each eyepiece, with the 28 being closest to the end of the barrel, and the 40 being furthest away. The eyecup has around 15mm range of travel on the 42 and 28, and closer to 21mm of travel on the 35.

The eye lens is very generous, and the coatings look quite good with no obvious blemishes or unevenness.

There is a safety undercut on the 2” barrel.

While they come with a cap for the field lens, the samples I received did not come with anything for the lens. Further, removal of the eyecup (for cleaning) was not obvious (I never did actually figure it out) so I’d recommend purchasing some bolt cases with the eyepieces themselves. For cleaning, I wound up just cleaning with the eyecup in place, as best I could. Since these are fairly large eyepieces, it turned out it was not really an issue.

The prices are fairly reasonable – especially for the 28. They currently list on the Olivon site at $62 for the 28mm, 71 for the 35mm and $88 for the 42mm.

Physically, I found them to be a fairly attractive eyepiece (especially the 35 and 28) – but we all know there are lots of attractive eyepieces on the market – the real question is – the one that you want to know before you lay down your hard earned money: how do they perform?

Performance and Comparison

In order to answer that, I had these for a couple of months and had opportunity to get them in a variety of telescopes. I’ve been seeing a lot of different equipment lately, and that coupled with my personal gear allowed me to get a pretty good feeling for how these eyepieces perform overall. I used these in everything from an 18” f4.5 Obsession to an f8.6 Tele Vue 102. They also saw duty in a WO-FLT-110 (f6.5), a 10” f5 DBA Certified SDO, a WO f5.9 fluorite doublet apochromatic refractor and probably a half dozen other telescopes besides.

In general I found their performance to be fairly good – at moderate focal ratios. The worst possible thing you can do to any eyepiece design is to stick it in a fast telescope and look at targets at the edge of the field. Even some of the most expensive and highly regarded designs begin to fall apart under f5. In fact, there are only a few lines currently available that are known to have good off axis performance in fast telescope – and most of these are EXTREMELY expensive. These aren’t in that ballpark. They aren’t designed to be.

The most common aberration found in simpler designs that tend to push their AFOV’s a bit further than they probably should is off axis astigmatism – and these definitely showed that at fast focal ratios. At f4.5, I’d estimate that only the inner 50% or so of the field was really sharp, but the residual astigmatism wouldn’t be enough to bother me if I were using them as finder eyepieces – which, with the exception of the 28, I would be.   Over the years, I’ve found that on nearly all my telescopes, my most used low power focal length is in the 20-24mm range. The 28 fit into that range pretty well, and thus quickly became my favorite of the set.

As you would expect, as I increased the focal ratio of the telescope, the edge performance of the eyepiece increased.   In particular I felt they hit a definite wall right around the f6 region.   In my f5.9 apo, I found edge correction to improve significantly.

I’d probably recommend these for f6 and longer scopes, but they did a fairly credible job (in terms of edge correction) at f5. Below that they went to pieces rather quickly. Frankly, given that this is (we think) a modified kellner design, I was pretty surprised it did as well as it did at f5 and f6.

Overall, correction was decent in regards to lateral color (not perfect, but well within what I would expect for an eyepiece in this range), and they provided pleasant sharp views.

I noted little to no blackout, and personally found the eye relief to be as comfortable as you could expect in a long focal length eyepiece.

Under the eyecup, I was unable to measure any of the eyelenses, but as I mentioned above, they were generous enough to give a nice porthole effect when viewing.

These eyepieces do have some advantages to other wide field eyepieces with more elements. Namely, with the minimal number of elements, I found that they provided very high levels of transmission and contrast, and even lower levels of scatter than I would have expected. On axis views were very sharp and bright - noticeably brighter in some cases than some other, older, multi-element designs.

For comparison, Hardin used to sell a 2” Astrola Kellner in the 32 (ish)mm range around this price point, and frankly, it’s performance was only moderately acceptable – ok, well - fairly horrid - at nearly every focal length I ever saw it in. While you could technically bring it to focus in a telescope, this Astrola’s best use was probably as a dust cover. I suppose I should more properly say that Hardin tried to sell it at this price point – I remember getting a couple for free (and giving em away too). Make no mistake - the Stratospheres have that particular Astrola beat 10 ways from Sunday.

Summary

Frankly, these are an interesting entry into the marketplace.    They aren’t perfect, but they may fill a need.

I think the 28mm presents a decent value for someone looking for a 2” introduction to the world of low-to-moderate power semi-wide field eyepieces.   Overall, the light weight of the line should appeal to dob or alt/az users – less weight means less rebalancing and thus, less hassle. High throughput will be appreciated by those looking to get the absolute deepest penetration out of their scopes – I found the 28mm an especially nice low power match for my little 66mm uber-tiny travel scope. For someone looking for just about the widest TFOV possible in a 2” eyepiece, the 42mm provides that – the 41 Panoptic will give you more true field, better correction (and more weight) but at 7x the price.

It would be nicer to see the price a little lower for the 42 – if you’re like I am, you tend to use those lowest power eyepieces very rarely, so it would be a bit harder for me to justify the 42mm at $88 when the 28mm can be had for $62. Perhaps the best value of the series is the 35mm; which at only $9 more than the 28mm presents a good compromise both fiscally and optically between the three.

If you’re seeking an inexpensive low power semi-widefield eyepiece with good transmission qualities, then these are certainly worth a look. While performance would be best in a long focal ratio telescope, these are nice and lightweight and thus should also bear some consideration for finder eyepieces in a dob. However I probably wouldn’t recommend them for use in scopes under f6.

If you visit the Olivon website, you can see they have another very interesting line of eyepieces in the works – and they shipped me a couple of those recently as well as some additional accessories – but you’ll have to wait for an upcoming article (or keep an eye out in the forums) for more details.