Kowa TSN-99A Spotting Scope
Expert Review
Review Highlights
- Incredibly bright, sharp, high-contrast images
- Massive 99-mm pure fluorite crystal objective lens
- Precise dual-speed focusing
- No detectable chromatic aberration
- Solid digiscoping options
Review Topics
We received a demo model of the amazing Kowa TSN-99A spotting scope for review and field tested it using two different eyepieces: the TE-11WZ II 30-70x zoom eyepiece and the TE-80XW fixed 40x extra wide angle eyepiece. First off, let us just say this spotting scope is a BEAST in every sense of that word! Putting this scope through its paces during field testing was an absolute joy! A little background information on this product line is probably in order. Kowa TSN-99 spotting scopes are available in both angled and straight models, with an A or S in the model number indicating the type. We only field-tested the angled version, and there are some differences from the straight configuration in weight, and length that we will discuss in the appropriate sections. Kowa TSN-99 scopes became available in the fall of 2021, and the wide angle eyepiece was released at the same time. The TE-11WZ II eyepiece is older, so generally speaking, availability of models or eyepieces should not be an issue.
Brightness and Clarity
It is hard to accurately describe the stunning brightness and clarity of this scope. One of the ways we field tested it was to take it on a shorebird survey. We were standing on a beach looking out to sea with the light from behind. Easily half a mile out, there were shearwaters flying by, and it was ridiculously simple to see their dark vents, confirming their identity. Similarly, distant foraging terns were child’s play to identify, as were the multiple species of cormorant and gull - well, most of the gulls… Many of these birds are notably difficult to ID, but with the level of detail this scope provides, the job is rendered much easier. The images were tack sharp all the time, which meant you swiftly moved beyond mere identification and into aging and sexing the birds. With the kind of light-gathering capability inherent in a large scope with great glass, the brightness on the TSN-99A was really impressive! As light fades at the end of the day, looking through this scope makes the world appear brighter than it does to your naked eye. This is the kind of optical instrument that makes you want to go back and see birds you’ve already seen through other scopes with this one, just so you can see them better!
Glass and Coatings
Glass and coatings comprise the core of this spotting scope – everything else is just details. The Prominar™ pure fluorite crystal objective lens is now combined with an XD element that reduces chromatic aberration to nothing. The XD stands for eXtra-low dispersion, and its purpose is to minimize chromatic aberration It works really well! We simply couldn’t detect any under field conditions! The fluorite crystal probably does most of the work in minimizing the chromatic aberration, but the combination is super effective. This does not sound like we’re saying much, but in fact, this is actually very significant. Chromatic aberration muddies images and views in subtle ways – you often don’t even realize that’s what you’re dealing with. But with the TSN-99A spotting scope, you don’t have to even think about it. Part of what allows this scope to produce such crystal sharp views comes down to the quality of lenses and coatings. All high-end optics these days are fully multi-coated; typically, the more you are paying for an optic (at least from a reputable manufacturer), the more layers of multi-coating they put on their products. And again, without delving into the science of how these things work, suffice it to say that Kowa’s multi-coatings are very good. One last coating that is worthy of special mention is the KR coating, which protects the lenses from dirt, reducing its tendency to adhere to the lens, thus making cleaning easier.
Eyepieces
The Kowa TSN-99 spotting scopes come with a choice of two eyepieces. Both eyepieces have bayonet mounts that lock into the scope body. To remove an eyepiece, you press a small button on the upper housing of the scope body and then twist. Recommended for general birding is the TE-11WZ II 30-70x zoom eyepiece. A minor drawback of this powerful scope is that you don’t really have an option for an eyepiece that gives you anything less than 30x magnification at the bottom of its range. There are compensations, however. The wide angle eyepiece is particularly useful when you are doing survey work or are on a Christmas Bird Count and trying to get a count on a distant large flock. We used this eyepiece to great effect while doing the shorebird survey, and found the broader field of view to be very helpful. In case the numbers don’t “speak” to you, the broadest field of view for the zoom eyepiece, at the lowest magnification of 30x, is 105 feet at 1000 yards, whereas the wide angle eyepiece, at 40x magnification, has a 111-foot field of view at 1000 yards. Typically, higher magnification means a smaller field of view, so this wide angle eyepiece really does deliver a much bigger field of view. Another important difference between the two eyepieces is that the 40x wide-angle eyepiece also includes a field flattener lens element. This kind of lens element is increasingly common on high-end optics these days, and it really improves certain aspects of their optical performance. That being said, it’s precisely because this is a wide-angle eyepiece that the field flattener is more useful than on the zoom eyepiece. This is also the reason why the wide-angle eyepiece is heavier: the weight of the glass in the lens element is telling.
| Eyepiece | Magification | Field of View @ 1000 yds | Eye Relief | Weight |
| TE-11WZ II Zoom | 30-70x | 105-60 feet | 17 mm | 13.2 oz. |
| TE-80XW 40x wide angle | 40x | 111 feet | 17 mm | 17.0 oz. |
Physical Properties
The Kowa TSN-99A spotting scope body is 14.9 inches long (37.8 cm) weighs 63.8 oz. (1.81 kg). If you don’t feel like calculating this in your head, that’s barely shy of 4 lbs., before you add an eyepiece. The TE-11 WZ II eyepiece added another 13.2 ounces of weight, bringing the package to 77 ounces (2.19 kg) – the better part of 5 lbs. total weight in the field. One thing we noted is that for most angled and straight spotting scope product pairs, there isn’t much difference between the two when it comes to weight. But this is NOT the case for the TSN-99 scopes, where the straight model actually weighs a bit more than the angled version, at 64.7 ounces (1.83 kg). It’s not a huge difference, but it’s an interesting one. In all these discussions of weight, it’s worth noting that the chassis on the TSN-99 scopes are made with a magnesium alloy, which is both lighter weight and more durable than other metal alloys Kowa could have used.
Both eyepieces add approximately 3.5 inches of length to the scopes. For the TSN-99 scopes, this makes it about 18.4 inches (46.7 cm) long on the angled version and 17.8 inches (45.2 cm) long on the straight configuration. These are the numbers that matter, because you won’t be going into the field without an eyepiece. Well, if you do, we can’t vouch for the quality of the view! One other difference between the 99-mm scopes and their smaller cousins is that the “foot” on which you attach the removable plate from a tripod was re-designed. It used to have a single screw mount that accepted 1/4-20 and 3/8-16 screws with a removable bushing that converted the hole size. The re-designed foot has two of these screw mounts, each with its own bushing so you can mount a plate with two screws, which is far better than just one screw and a plastic anti-twist pin. This change makes it far easier to mount the scope more securely on the plates of various tripod brands. All the individual components of the optical system, scope bodies and eyepieces, are water-tight, dry nitrogen-purged and completely waterproof.
Focusing
Most of the currently available Kowa spotting scopes use the same dual focus knob system, and it’s a very good one. It is easy and intuitive to use. The wider diameter knob nearest the viewer is the coarse focus, and the smaller diameter knob closest to the objective lens is the fine focus. The knobs are coated with ribbed, rubber armoring, and the focusing action is facile with just the right amount of resistance. It’s smooth and easy to adjust, but it’s not so loose that it doesn’t stay put where you leave it. So Kowa gets full marks for their focusing system. One statistic that we haven’t mentioned so far is the close focus distance. And it probably sounds sort of silly to think about since, duh, we use spotting scopes to see things that are far away. But we also use them to see things better and occasionally those things are nearer. This detail is especially relevant if you’re digiscoping to get closer photos. And that’s where the close focus distance comes into play. The TSN-99A scope has a close focus distance of 19.7 feet (6.0 meters). That means you have to be at least that far away to get a sharp image through this scope.
Digiscoping and Accessories
Kowa offers dedicated digiscoping adaptors that fit the TSN-99 spotting scopes. For attaching a camera with a lens, the TSN-DA10 Digital Photo Adaptor screws onto the threads revealed by removing the eyecup from whatever eyepiece you are using. Alternatively, the TSN-PA7 adaptor allows you to mount the camera body directly on the scope eyepiece. At this point, we cannot say how well it actually works on the TSN-99, because these are aspects of this system that we didn’t get a chance to test. That being said, it’s the same adaptor we have previously used with the 88-mm Kowa spotting scopes, and it works quite well. We recommend two things if you want to do this with the TSN-99 spotting scope: 1) make your life easier and purchase the straight-through TSN-99S model if you intend to digiscope with it. It’s a lot easier to aim and getting the height of the system right is easier when you are shooting straight through. 2) Get a really steady tripod, to counter-balance the weight of both the scope/adaptor combo and whatever camera you’re attaching to it. For that, we recommend a carbon fiber tripod, both for its lower weight and for its vibration dampening qualities. There are a lot of accessories related to digiscoping, and it’s really outside the purview of this article to go over all of them separately. However, additional tips for this would include getting a fluid video head type for the tripod, preferably one with a QR sliding plate to facilitate counter-balancing the weight of the camera. Suffice it to say that whatever your camera, you can get what you need to make it work for digiscoping. There are also ways to digi-phone with spotting scopes, using Kowa’s phone adaptor or that of another manufacturer. A lot of these options are pretty sophisticated these days and a solution can usually be found for any type of phone. And these things may actually produce very good images. Remember that the quality of the glass in front of the camera is a huge determinant of the image quality resulting from it, and Kowa’s Prominar™ pure fluorite crystal lenses are better than any glass!
There is one additional accessory that we heartily recommend for the TSN-99 spotting scopes, and that is the fitted, padded case. Basically, these cushion and protect your investment in multiple ways. Kowa’s scopes do not come with any armoring on the scope body, so a case is extra important here. You can always buy a padded case from a manufacturer other than Kowa, but such cases typically don’t fit as well and the hassle you will encounter isn’t worth money you might save with a third-party manufacturer’s case.
The neck strap is the usual hybrid of cordura, foam rubber and plastic parts, but that’s where the similarity to a conventional binocular strap ends. Swarovski redesigned their neck strap from the ELs. One of the great features of their strap is how easy it is to adjust the strap length. This is really well designed. A couple other things come with the binocular, including a little soap and soft brush set and an optic cloth, both for cleaning it. We still recommend getting a lens pen to assist in cleaning any binocular. Using the lens pen to remove grit before you rub the lens with anything will help preserve those coatings that are so critical in providing the great image quality of the NLs.
Conclusions
The TSN-99 spotting scopes are both offered as body only purchases (if, for example, you already own an eyepiece that would fit them) and as a “kit” including the TE-11WZ II zoom eyepiece. Prices for these are laid out in the table below.
| Scope Body | Eyepiece Mount | Eyepiece | Price |
| TSN-99A | Angled | w/30-70x | $4,199.00 |
| TSN-99S | Straight | w/30-70x | $4,199.00 |
| TSN-99A | Angled | Body only | $3,450.00 |
| TSN-99S | Straight | Body only | $3,450.00 |
In the end, these spotting scopes are a joy to use. Birding is hard enough. Photography is hard enough. Having a superb optical platform to do those activities with makes life a lot easier and more pleasant! When you start to compare the prices of Kowa scopes to those of other manufacturers, you realize that in addition to being great scopes in their own right, they are also good bargains. We here at Optics4Birding feel that you simply cannot go wrong with a Kowa TSN-99 spotting scope.