Kowa TSN-66A PROMINAR Zoom Kit & TE-80XW Eyepiece Review

Back in 2021, I wrote a piece on the mighty Kowa TSN-99A Prominar Spotting Scope Zoom Kit. Whilst using Kowa’s flagship spotting scope under field conditions it didn’t take me long to realise that I was in the presence of optical greatness. My musings on the subject can be found here: Kowa TSN-99A Prominar Spotting Scope Review.

The TSN-66A Prominar

Courtesy of the nice people at Kowa, I recently got my hands on one of the TSN-99A’s smaller stablemates: the Kowa TSN-66A Prominar Spotting Scope Zoom Kit, no less. As the name suggests, we’re looking at a 66mm diameter objective lens here, as opposed to the whopping 99mm offered by the larger scope. In ‘Zoom Kit’ form, the 66A body comes with the tried and tested TE-11WZ ll zoom eyepiece but Kowa also very kindly also provided me with a second eyepiece: the TE-80XW. This is a fixed magnification model which provides an extra wide (80 degree) field of view.

Fixed eyepieces were once very popular but are fairly rare beasts these days, so the option to have both fixed and zoom variants does give any existing or potential Kowa user a certain degree of enhanced flexibility.

I first encountered the TSN-66A in the flesh at Global BirdFair back in July 2023. The 66mm models had just been released and, quite frankly, the sheer quality of the image pretty much rocked me back on my heels.

I knew that optical performance would be excellent but, having already experienced the 88mm and 99mm scopes, I think I half-expected the 66mm objective to be noticeably less impressive in some way. As it happened, I couldn’t have been more wrong. First impressions count and as soon as I took my first tentative look I knew that this was another killer spotting scope from Kowa, albeit in a slightly more compact form.

As with pretty much all of Kowa’s scopes, the TSN-66 models are available in both straight and angled variants and, in terms of appearance, they bear a strong resemblance to their larger siblings.  All models sport the same green, anodised finish with that distinctive red ring around the barrel; Kowa’s way of indicating premium glass for the best part of forty years.

Crystal clear

Where Kowa’s Prominar series is concerned, premium glass comes in the form of an objective lens which is made of pure fluorite crystal. Kowa is the only sports optic manufacturer to offer this feature and only uses the term ‘fluorite’ to describe pure fluorite glass – worth noting!

Flourite is difficult to work with but the main advantage it gives is almost complete elimination of chromatic aberration, i.e. the colour fringes which are often visible around the edges of a subject, particularly at high magnification. Every Prominar scope I’ve ever looked through has been excellent in this regard and the test model was no exception: a beautifully bright, clean, sharp image with very natural colour rendition and reassuringly free of aberrations, even under poor lighting conditions.

Ergonomics

Kowa Prominar bodies are 100% magnesium alloy (very strong, yet light) and, as we’d expect from a premium optic these days, they’re all nitrogen-filled and fully waterproof. Each scope boasts a slide-out lens shade (as shown in the image below) and I can confirm that said shade slides out and retracts very smoothly indeed.

When I first reviewed the TSN-99A three years ago, one slight disappointment was what I perceived as a missed opportunity for Kowa to move to an Arca Swiss footplate.

The Arca system helps prevent your scope from swivelling loose on the tripod head during transit by fitting the footplate directly into the tripod head without any need for a quick-release plate.  I’ve fallen foul of that very issue in the past, but what Kowa has done with all of these scopes is to tackle that very issue by including two threads in the base plate.

Like this:

My current tripod release plate came with two screws – one 1/4” and one 3/8” and, once those were both deployed, I can confirm that the TSN-66A stayed very firmly attached with no need to keep tightening things up again every five minutes – something which has been a bugbear with other scopes in the past. With the 66A, I found myself having to re-tighten occasionally, but maybe only once every third or fourth sortie into the field; so Kowa’s system, whilst very simple, is also very effective in tackling a common irritation.

In focus

It would be remiss of me to talk about any of the Prominar scopes without making a mention of Kowa’s legendary dual focus system. This involves two focus wheels, one for coarse focus (or quick focus, if you prefer) and one for making fine adjustments in order to bring your subject into the sharpest relief possible.

The two wheels are ergonomically positioned atop the body of the scope and, in my view, represent the best focussing system out there. Each wheel operates smoothly but with just the right amount of resistance and the fine focus adjuster allows pin-sharp images to be achieved – vital when digiscoping, for example. Having the focus wheels mounted on top of the scope also allows the scope to be used whilst resting on a bean bag – an advantage over helical focus rings (the ones that go all the way around the body) so possibly worthy of note.

Comparing eyepieces

The TE-11WZ II eyepiece is already a well-established product in its own right. There’s been lots written about this model over the years so I won’t dwell on it for too long. Suffice it to say that this is quite simply one of the best zoom eyepieces out there. Magnification is 25-60x with Kowa’s 66mm and 88mm Prominar models, increasing to 30-70x when used with the 99mm scopes.

I’m not the biggest fan of zoom eyepieces in general but this one is definitely one of the exceptions; just wonderfully sharp and bright with only a very slight drop-off in performance right at the top of the zoom range. More often than not, I found myself scanning at 25x and then zooming up to 50x as I found this provided the ideal balance between power and clarity.

The ‘W’ in the name signifies that this is a wide-angle ocular and I can confirm that there’s no sign of the tunnelling effect which is so prevalent with some zoom eyepieces. Kowa offers its Prominar spotting scopes as ‘body only’ or as a kit with the TE-11WZ included. For anyone buying their first spotting scope or making the switch to Kowa from another brand, a zoom kit does look like the sensible and logical choice as it gets you up-and-running straight away…just add a tripod!

But what of the other eyepiece I mentioned? What of the interestingly-named TE-80XW? What does that bring to the table?  

As I mentioned earlier, this is a fixed magnification eyepiece. Magnification is set at 35x with the 66mm and 88mm models, increasing to 40x when used with  the TSN-99A or TSN-99S.

Not too long ago, fixed eyepieces were a popular choice and pretty much all brands offered at least one version. Over the last couple of decades, however, zoom eyepieces have improved quite dramatically in terms of optical quality. As a result, fixed eyepieces have declined markedly, to the point where some manufacturers now offer a zoom eyepiece as the sole option….but not so with Kowa!

Naturally, the TE-80XW doesn’t offer as much versatility as a zoom. What it does offer, however, is a beautifully wide field of view with terrific clarity, colour fidelity and outstanding edge-to-edge sharpness. And when I say ‘wide’ I mean W…I…D…E!  All of these factors combine to give a very immersive viewing experience and, if your main interest is sea watching or scanning for raptors, to give just two examples, that’s where this eyepiece really fits the bill.

I always find a good-quality fixed eyepiece to be a bit more relaxing to use, particularly over extended periods. Apart from the fact that you’re (quite literally) looking at the wider picture, there’s no temptation to keep fiddling with the zoom magnification all the time – something to which I am somewhat prone whenever I use a zoom.

Nope, with a good old fixed eyepiece you just find your target, focus and you’re done. In that regard, it’s a bit like a photographer using a prime lens as opposed to a zoom lens. Which leads rather neatly onto…

Phonescoping.  For anyone with an interest in capturing smartphone images or video, the TE-80XW also has a major trick up its sleeve: the wide field of view means that this eyepiece is extremely effective at eliminating vignetting, even when using your smartphone’s 1x camera. Vignetting is the black border you often see around the edges of the image once you’ve connected your phone to your scope.

Using my iPhone 14 Pro in conjunction with the TE-80XW, I was able to use the 1x camera in photo mode, video mode and cinematic mode all with no vignette whatsoever. Given that your 1x camera lens is likely to give the highest quality images, I feel that this is worthy of mention, but images are probably the best way to illustrate this so here’s a couple of moulting/slumbering Anatidae.

Taken in photo mode, using the 1x phone camera lens and TE-11WZ ll zoom eyepiece with magnification set to 35x:

And the same Anatidae captured in photo mode with a 1x phone camera but using the TE-80XW eyepiece, giving magnification of 35x:

The wide-angle eyepiece also comes to the fore when the birds have spread themselves out a bit. When there’s two Pied Flycatchers rather than one, for example. With the zoom eyepiece I think I’d still have picked up the second bird but I think it would have been right at the edge of the field of view and possibly even partially cut off:

PiedFlycatcher Video

I should mention that all images were taken using the Smartoscope Vario adapter to mount phone to scope. For further reading, see here: Ultimate Smartoscope Vario-Adapter Review.

Choosing your kit

I think most birders are already aware that Kowa spotting scopes sit right at the top of the tree when it comes to image quality. Personally, I’d love to see the company produce a binocular to match the scopes (imagine pure fluorite crystal in a bin!!!) but, for now, we have the Prominar scope family to be going on with and my personal view - which spending time with the 66A has served to reinforce -  is that even the most demanding of users would be hard-pressed to fault the image on offer. Make no mistake, we are talking top, TOP optical performance here! But what of the eyepieces? Which one wins out?

Well, this is a tricky one because, inevitably there is always going to be a degree of ‘horses for courses’ at play. Both are optically outstanding; the fixed model is a dream to use when you need the widest field of view possible whilst there’s no denying the sheer versatility of the zoom with the option of extra power when it’s needed.

Having given the matter a not inconsiderable amount of thought I’d say that the pre-boxed zoom kit is probably the wise choice for all-around general birding bearing in mind that you can always add the fixed eyepiece at a later date. BUT (and this is a big but, hence the capitals) if you’re a dedicated sea watcher, if you spend a lot of time scanning for raptors, or your main interest is digiscoping you may prefer to go with body plus TE-80XW straight from the get-go… and that makes perfect sense.

I guess what I’m trying to say here is that you can’t really go wrong with either, it’s more a matter of personal preference and what your primary use is likely to be.

I spent a LOT of time in the field with the TSN-66A and both eyepieces and, no matter which eyepiece I started out with, I invariably found myself switching to the other at some point. It was really nice to have the choice and being able to swap definitely gives the Kowa user an extra degree of versatility.

It’s also worth bearing in mind that Kowa also offers the TSN-EX16 1.6x Extender, the TSN-1.25K Adapter for Astronomical Eyepieces and a plethora of digiscoping add-ons for their spotting scopes so, when you purchase a Kowa Prominar, you’re buying into a system and all the flexibility that comes with it. Kowa also produces some really nice neoprene stay-on cases to add an extra layer of protection for your flagship spotting scope and that’s well worth being aware of too.

To wrap up

In summary, the TSN-66A Prominar has to be one of the best spotting scopes I’ve ever used. There’s just no getting away from the sheer clarity, brightness, sharpness and natural colour reproduction offered by that 66mm pure fluorite objective; perfect for revealing the wonders of the natural world in all its multicoloured glory. The dual focus system offers flawless operation and I’ve spoken to many birders who’ve cited it as one of their main reasons for choosing Kowa. Add a couple of truly exceptional eyepieces to the mix and you have a killer combo on your hands.

Thank you for reading. I hope you’ve found this blog interesting and informative and, as always, Happy Birding!

STOP PRESS: since I began writing this article the Prominar range has been boosted by the addition of two 55mm models (one straight and one angled) each weighing in at under a kilogram. This adds a really nice travel option to the Kowa’s spotting scope roster so, if you’re in the market for a new spotter, Kowa has you covered!

Shop the TSN-66A Prominar

Get your hands on a Kowa TSN-66A PROMINAR Zoom Kit today.

Read next

• Kowa TSN-99A Prominar Spotting Scope Review
• Ultimate Smartoscope Vario-Adapter Review
• Best Backpack for Spotting Scopes | Vanguard VEO Active Birder

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