Kowa TSN-663 ED telescope

It was only last year that Kowa pulled off a major coup with the launch of the TD-1, the world’s first telescope to include a built-in digital camera. Prior to this, the company had long been renowned for its production of high quality telescopes, which continue to retain a significant element of popularity among birders throughout the world. One of these models, the TSN-663 ED, has been on the market for two years, and I recently took it out for extensive testing in the field.

This is an angled-eyepiece scope with a lightweight polymer body, and is finished in the long-established corporate colour of light grey-green. Weighing a fraction over 1 kg, and with a 66 mm objective lens, it is very much a mid-range player in terms of size but, when used with the zoom eyepiece, it leans towards the top end of the range in terms of price and performance.

I used it successfully in conjunction with a light (1,320 g) carbon-fibre tripod and simple ball head – the combined ‘over-the-shoulder’ carry weight amounted to less than 2.4 kg.

Although I am not a fan of angled eyepieces (the straight-bodied equivalent is the TSN-664), I quickly found it easy to adjust to and to use. The 20-60x zoom eyepiece is a simple bayonet fit and, although there is no locking device to secure it, it stays firmly in position and can be removed only if some significant turning pressure is applied to it ‘beyond’ the 60x magnification limit. There is an integral milled ring to adjust the magnification on an incremental scale between 20x and 60x, and a small, fixed red marker on the side of the eyepiece indicates which magnification has been reached. However, users have to learn where the marker is because it is so tiny, and it is not visible at all in poor light! Adjusting the magnification is very easy: although the milled ring is the principal point of finger contact, the whole of the lower part of the eyepiece (53 per cent of its length) actually turns – very smoothly – allowing three-finger contact if desired. The eyecup is overlaid with firm but soft rubber, and twists out to click-stop in no fewer than five different positions.

The body is nitrogen-filled and fully waterproof, with the foot (tripod attachment) mounted on a collar. This can be loosened by a finger-operated retaining screw to allow the scope to be rotated on a tripod to alternate between landscape and portrait photographs if used with a camera, or to look forward or backward if used with a car window mount. There are discernible click stops within the circumference of rotation but tightening the screw effectively locks the scope in any position.

I have used a number of scopes on which the objective lens hood sticks to the barrel when you attempt to extend it. Not so this one, which glides out smoothly as if on a cushion of air, even when wet. Recessed threading inside the end of the barrel allows the attachment of a screw in objective lens protection cap, which also locks the hood in place.

The knurled focusing knob is offset to the right, turns smoothly and easily and is approximately one and a half ‘fingers’ wide. I must confess to finding it a little too sensitive and, because of this, trying to obtain a sharp image was sometimes difficult without a little perseverance, particularly when wearing gloves.

When you get there, though, it’s worth it. The image is crisp, bright and sharp to the edges of the field, with wholly natural, true-to life colour tones with no detectable colour fringing. The brightness and clarity of the image is no doubt a reflection of the ‘ED’ specification, which centres on the use of fluorite glass for the objective lens, and the fully multi-coated glass elements used within the scope generally. In the dull, wet conditions of a fading winter’s afternoon I found there was still some mileage to be squeezed out of this scope in terms of brightness and the delivery of a more than acceptable image. It is also worth noting that a 66 mm objective has in excess of 20 per cent more light-gathering capacity than a 60 mm objective so this, too, would contribute to a noticeably superior image if compared with a smaller scope – for instance the TSN-601 – within the Kowa range.

I did not test the scope with any fixed magnification eyepieces, although 20x, 25x and 30x wide-angle eyepieces are all compatible with this model.

So, if you’re looking for a medium-sized scope with some clout and you don’t want to pay top-of-the-range prices, the TSN-663 is certainly worth a look.