Once again thanks to the collaboration of Kowa Optimed Deutschland Gmbh I was fortunate enough to observe and photograph with the brand new KOWA TSN-66 PROMINAR. It is available in an angled version called ’TSN-66A” and a straight version ”TSN-66S“. I reviewed the angled model in the “ZOOM KIT” version which currently costs €2,698.00. It is in fact offered with the well-known TE-11 WZ II zoom eyepiece which allows for a magnification range between 25x and 60x. As you will understand, therefore, while obtaining the same magnification range as the TSN-88, its focal ratio is “longer’ than the larger diameter models and this It already bodes well for excellent performance, however… if you want to know more I recommend you watch the video review and read the article.
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STANDARD ACCESSORIES
Having received one of the first telescopes available, the Kowa TSN-66 A arrived without the official accessories. Kowa confirmed to me that the zoom kit available to the public will include the following accessories:
- TSN-66A PROMINAR Angled Riflescope
- TE-11WZ II 25-60x Wide Angle Zoom Eyepiece (I think with green velvet pouch and caps)
- Lens cap
- Lens cleaning cloth
ACCESSORIES CAN BE PURCHASED SEPARATELY
Loyal KOWA readers know that purchasing a spotting scope opens up a world of possibilities, thanks to the wide range of adapters available for observation and photography with both DSLR and mirrorless cameras and smartphones. In this case too, KOWA offers a series of suggestions for accessories to consider.
Recommended options include:
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TSN-DA10 Photo AdapterThis accessory, costing 149 euros (excluding the adapter ring), makes it easier to connect mirrorless cameras to their lenses, allowing for a photographic experience without compromise.
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Kowa TSN-EX16 1.6x Teleconverter: At a price of 329 euros, this focal multiplier expands the creative possibilities of each of us, allowing us to obtain even closer and more engaging details.
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TE-80XW Wide Angle Eyepiece (35x): At a cost of 699 euros, this eyepiece offers a wide-angle field of view without sacrificing sharpness and contrast, enriching the observing experience.
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TSN-RP adapter: Available for 117 euros (excluding adapter rings), this versatile adapter is particularly suitable for connecting most smartphones to the TSN-66, making it an essential component to consider for those who want to take full advantage of the potential of this compact yet high-performance spotting scope.
MECHANICS AND FOCUSING SYSTEM
As mentioned previously, the new KOWA TSN-66 is available in two variants. The angled configuration (defined by the letter “A”) is aimed specifically at birdwatchers and nature and sky lovers, while the straight version (S – straight) is perfectly suited to the needs of sport shooters and hunting enthusiasts.
This spotting scope is built and assembled in Japan and is designed to withstand impacts and harsh weather. Similar to the KOWA TNS-99 and TSN-88, a thixotropic alloy molding process was used. Specifically, this involves magnesium injection molding, which allows for the creation of optical enclosures with a complex, precise, lightweight, and robust structure. My electronic scale, in fact, estimated a weight, without eyepiece, of 1142 grams which becomes 1514 grams with the TE-11 WZ II mounted.
Among the various innovations (already present in the new TSN-88 and TSN-99 models), as I previously indicated, the following immediately emerges: the appreciable new design in the area adjacent to the eyepiece. This design incorporates a black anti-slip armor and introduces a new, more powerful button for attaching and detaching the eyepieces.
The long foot, equipped with two threads with 1/4 and 3/8 pitches, ensures extremely secure attachment. This fixing mechanism prevents any unwanted movement of the spotting scope, both when transported on a tripod and when a DSLR or mirrorless camera is connected via the TSN-DA10 system.
For those who want to use it along the sea shores, on cliffs and during adverse weather conditions, I highly recommend considering purchasing a 72mm diameter protective filter for the front lens.
Another design improvement (already seen on the TSN-99 and TSN-88) concerns the dust ring in the eyepiece area. This ring performs a protective function, safeguarding the thread that allows for the attachment of a wide range of accessories. In conclusion, the new features of the TSN-88 and TSN-99 models offer a series of improvements that go beyond aesthetics, contributing to a more reliable and functional user experience.
The excellent focusing system, of course, remains unchanged. It features a knurled ring assisted by a gear reduction system that facilitates accuracy during the more delicate focusing phases, such as adjusting the focus point via the camera's display during digiscoping.
The minimum focusing distance I measured at 25x is three and a half meters, while at 60x it is four.. From this distance, I had to rotate the knob (counterclockwise) just under a turn and a half to reach infinity focus (at 60x, the travel is slightly more).
I believe that the KOWA focusing system is better than many collar systems, not only for precision but also for the possibility of generating less vibration during critical focusing phases, for example when focusing beyond 2000mm focal length.
However, when using collar rings, I generally tend to apply more pressure to the optical body. It's clear, therefore, that I always appreciate the gear reduction system developed by Kowa, which has been on the market for many years.
OPTICS
Objective
Compared to the competition, Kowa stands out as the only company to use pure fluorite crystal in its prestigious high-end product lines, such as the TSN-99, TSN-880, TSN-550, and the “legendary” Kowa Highlander.
Conversely, other companies rely on ED glasses that also include fluorite in their composition. Readers will recall that mixed glasses are easier to work with than fluorite crystal, which requires considerable skill, especially when producing diameters greater than 60-70 millimeters.
A notable aspect of using pure fluorite crystal is its exceptional ability to reduce chromatic aberration. And since the zoom eyepiece provides the same magnification as the TSN-88, it's easy to understand why the TSN-66 has a shorter focal ratio. For this reason, the correction of chromatic aberration (and spherical aberration) is excellent!
I can already confirm, in fact, that the new Kowa TSN-66A, with which I had the privilege of interacting, It offers very high quality images, furthermore the images are neutral with vivid and bright colors (in proportion to its diameter).
In my opinion, the KOWA TSN-66 is currently one of the best performing spotting scopes available on the world market.
Anti-reflective treatment
As I mentioned in my reviews of the new TSN-88 and TSN-99, Kowa's engineering team has made significant improvements to previous optical coatings, both on the lenses and the prism. This effort has led to the creation, once again, of an observation telescope that offers even higher wavelength transmission levels than spotting scopes from just a decade ago. This improvement extends across the entire visible color spectrum, helping to provide a viewing experience with even more natural colors that faithfully represent the diverse beauty of the surrounding nature.
TE11-WZ II zoom eyepiece
Readers who have been following me since 2006 will remember my previous review of the first generation TE11-WZ zoom eyepiece. The new model is practically identical even if it has been improved with the new hydrophobic and oleophobic treatment "KR". This second generation eyepiece also features, therefore, in its optical scheme, two XD lenses. (low dispersion) which serve to correct chromatic aberration as effectively as possible. Furthermore, it benefits from a constant 17 mm eye relief throughout the entire magnification range. Although the TSN-66 loses a little in brightness compared to its larger diameter siblings, it has proven to be an excellent all-rounder for both visual observation and photography. To learn more, I invite you to read my previous review by visiting the following link.
Kowa TE-11 WZ eyepiece
CHROMATIC AND GEOMETRIC ABERRATIONS
Having had the opportunity, thanks to the astronomical adapters mentioned above, to use many third-party eyepieces, I can confirm that both chromatic and geometric aberrations vary slightly based on the magnifications and eyepieces used.
Aberration analysis with the Kowa TE-11 WZII eyepiece.
Chromatic aberration at the center of the field
I would say invisible, even in the worst lighting conditions. It is one of the best results obtained, it competes with the excellent Zeiss Harpia and is better than the Swarovski ATX. The observation at over 153X with “TWO” focal multipliers was incredible, I would have expected an evident chromatic aberration, but as you can see in the video and in this image, Kowa amazed me. No chromatic aberration on the lunar limb, the same is true for Jupiter and Saturn.
Lateral chromatism
While I had noticed some lateral chromatic aberration in the worst lighting conditions with the TSN-99 and TSN-88, this time, with the TSN-66 I was unable to notice it. This is an excellent performance.
Field curvature
In daytime use at both 25x and 60x I did not notice any obvious degradation at the edges of the field and personally I consider it a spotting scope without field curvature.
Angular distortion
In analyzing this aberration, however, I noticed a bit of pincushion distortion towards the 85% from the center of the field. I didn't have the opportunity to make a comparison with the Kowa TSN-88, but going from memory, it seems to me that the TSN-66 corrects it slightly better.
Other aberrations in astronomical use
In astronomical use, with the TE 11-WZ II zoom eyepiece, stars at 25x maintain excellent pinpoint sharpness right to the edges of the field of view. With high-quality eyepieces like the Docter UWA 12.5mm, the star image is even sharper across the entire field., with astonishing contrast and quality. This rendering can be compared to that observed through a high-quality astronomical refracting telescope.
Increasing the magnification to 60x with the same zoom eyepiece, while observing the brightest stars I noticed a slight presence of astigmatism, however, this effect is not particularly significant or annoying.
USAF CHART TEST AT 35 METERS
If I had to name the best USAF CHART test of the year, I'd cite this one. During the day, it performed practically the same as the KOWA TSN-88A, falling only slightly short at 60X, in the sense that the lines at number "3" were slightly more visible in the TSN-88. The obvious brighter image aside, the TSN-66 A provided a sharp and contrasty image "like a high-quality astronomical refractor" with, what's more, a total absence of residual chromatism even at 60X. This is not a given, even for a TOP OF THE RANGE telescope.
PHOTOGRAPHING WITH THE KOWA TSN-66A
Digiscoping
Whenever an enthusiast asks me which company offers the widest range of photographic accessories for digiscoping, my answer is always Kowa. When it comes to Kowa spotting scopes, I always recommend using the TSN-DA10 adapter with a lightweight mirrorless camera, such as one with a Micro Four Thirds sensor. However, given the compact size and light weight of the TSN-66 A, I feel inclined to suggest the phonescoping approach, that is, using a simple, lightweight smartphone.
I personally use the universal smartphone adapter Smartoscope Vario, as I need to use it with different eyepieces and smartphones. However, the TSN-RP adapter could be an ideal solution, especially when paired with smartphones with high photographic capabilities. As you will see, the clips in my video review were all shot with one https://www.termicienotturni.it/recensione-smartphone-cat-s62-pro/ I use it primarily as a rugged work tool and it's not known for its top-notch photographic performance. However, as you'll see, capturing herons from over 100 meters away at 9:00 in the morning provides ample evidence of the TSN-66A's capabilities.
IMPRESSIONS ON THE FIELD
Naturalistic observation
I've also frequently used the TSN-66A with an old General HI-T carbon fiber tripod, which I've been using happily for almost twenty years and which could easily sit in a pub and tell a thousand adventures. On this tripod, I've sometimes mounted a lightweight Manfrotto 701 video head and other times a small Sirui ball head.
The more I used the KOWA TSN-66A, the more I realized that, for certain types of observations, it is not necessary to have a powerful 95-99mm telescope with you.
While these are brighter and more effective for photography, they may be too bulky for bird-of-prey viewing, which may involve long hikes. During a walk in the Palude Brabbia Nature Reserve, I also appreciated the remarkable contrast, sharpness, and color rendition offered by this small spotting scope. For primarily daytime use, I believe the TSN-66A can effectively replace the 773 series model and is undoubtedly a higher-performance telescope than the 56 mm models that have recently attracted renewed interest.
Personally, I encountered the same enthusiasm among amateur astronomers when the first 66mm telescopes with ED optics were introduced years ago. These instruments were universally appreciated because, despite their compact size, they were able to reveal details on the Moon, Jupiter, Saturn, and Mars. Even in the birdwatching field, I confirmed what I had previously observed with the USAF CHART test: the sharpness is exceptionally high and the chromatic aberration correction is so superb that the images displayed in full daylight are undoubtedly among the best ever observed.
Of course, this isn't an 88mm telescope, so in dense vegetation, among reeds, or at twilight, the difference will be noticeable. However, if you're looking for a lightweight yet high-performance spotting scope, the TSN-66A might be your best bet right now.
Twilight observation
Admittedly, I didn't have much opportunity for this type of observation, as I would have liked to compare the TSN-66A with the TSN-773. However, thanks to the large prism and excellent anti-reflection coating, I was able to satisfactorily appreciate the sight of deer and foxes in the early moments of twilight. It might have been preferable for me to have a specific eyepiece from Kowa that offered magnification between 12x and 15x, in order to take advantage of a larger exit pupil. However, I understand that this may not be the specific field of action of this spotting scope.
Astronomical observation
If you were considering investing the sum required to acquire this excellent (but small) spotting scope, it might make more sense to opt for a larger diameter astronomical telescope. However, My considerations come into play if the purchase is oriented towards naturalistic use and you also want to make occasional observations of the deep sky, the Moon and the planets.
What did I notice? First, I noticed that, while it shares the same focal length as the TSN-88 (i.e., 500mm), the focal ratio is slightly smaller, approximately F7/6. As the owner of a 128mm fluorite crystal doublet telescope with an aperture of F/8, I'm well aware of the positive effect a medium-high focal ratio can have when using a fluorite crystal.
Star test
In fact, I noticed a good correction not only of residual chromatic aberration, but also of spherical aberration. The star test turned out to be among the best I've ever done on a spotting scope, with the exception of a slight stray light at extra focal length. The star images are well corrected, sharp and pinpoint, while the lunar limb is completely free of residual chromatism.
I was able to observe Saturn and its rings clearly, although the observing conditions this year were not optimal, using the Kowa TSN-EX16 multiplier.. I also used Kowa adapters with Takashi HI-LE and LE eyepieces. Even the brightest galaxies are clearly visible from my backyard, thanks also to the excellent contrast that separates them from the background sky. For high magnification observations, based on what I described above, I would recommend purchasing the Kowa multiplier, mainly because it could be used extensively during daytime observing (provided that turbulent conditions allow it).. Despite a slight decrease in brightness, sharpness and contrast remain very high, in fact even at 96x magnification, observing the Moon and knowing its main features would keep you entertained for hours and hours.
In conclusion, there are numerous astronomical telescopes to choose from for the same price. However, a high-quality product will always deliver its full potential, both for nature and astronomical use.
PROS AND CONS
Pros:
- Objective lens with pure fluorite crystal
- Excellent sharpness
- Excellent color rendering
- Excellent chromatic aberration correction
- High contrast
- USAF CHART daytime test similar to a larger diameter spotting scope
- Compatibility with the Kowa doubler in daytime conditions and for lunar observation
- Complete photographic system, among the most advanced currently on the market
- Best current compromise between compactness and performance
Defects:
- High purchase price, in line with high-end competition
- Kowa has only made one fixed-magnification eyepiece. In addition to the 40 TE-XW eyepiece, I would like to use a 15x, to further enrich the options.
IN SUMMARY
Kowa is a company that doesn't rush into frequently evolving its instruments over the years, but when it introduces a new product, it always does so with care, intelligence, and expertise. I believe the new KOWA TSN-66A will soon become one of the most sought-after spotting scopes, especially among serious hunters, sport shooters, and birdwatchers. It combines the advantages of the TSN-883 in a significantly more compact body, and its exceptional sharpness, contrast, color rendition, and color retention will undoubtedly be a serious warning to even the most aggressive competitors. I strongly suggest you overcome any preconceived notions based on brand recognition and visit your local dealer to try it out for yourself. I'm sure you'll be pleasantly surprised, as I was.
PRICES
The “ZOOM KIT” version currently costs €2,698.00. Suggested retail price for the month of August is Kowa Optimed Deutschland GmbH
THANKS
I thank Dr. Gunter Reisner of Kowa Optimed Deutschland GmbH for providing the instrument under review, allowing me to share my unbiased impressions.
DISCLAIMER
Binomania is not a store. On my website, you will only find reviews of sports, photographic, and astronomical optical products. My opinions are impartial, as is the duty of any journalist, and I do not take any percentage of any sales from any product purchases. For this reason, if you would like to purchase or have information on any price changes or new products, I recommend visiting the official website. Kowa Optimed Deutschland GmbH By clicking on the banner, which is the only form of advertising in this article. Thank you.!
Piergiovanni Salimbeni - Journalist and independent tester, founder of Binomania.co.uk, with over 25 years of experience in evaluating optical and digital instruments. It offers practical reviews and personalised advice for informed purchasing choices.