9.06.2020 Kowa TSN-884 1.25" astro eyepiece adapters & binoviewer.

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I purchased the astronomical eyepiece adapters at the same time as the telescope. I have inverted one of them for the photograph to show the details but they are essentially identical. Which seems rather pointless. The thumbscrews make it impossible to screw in the adapter!

The one with the hidden grub screws means that the eyepiece has to be fixed into the adapter first, and the grub screws tightened, before insertion into the telescope. The zoom eyepiece having been removed first to expose the internal thread.

I mention this early in my description of the telescope system because I want to try binoviewing with the superb Kowa optics. Which meant using one of the adapters to hold the binoviewer spigot firmly in place.

These images show how I tested the basic concept using an old, no-name 20mm eyepiece and one of the adapters. I was easily able to reach focus [and well beyond.] While the resulting image was superbly sharp and bright. Providing a power of 25x to match the lowest zoom magnification.


The images on the right right show the result of removing the ring which protects the large male thread intended for digiscoping and also to accept the 1.6x Kowa Extender.

The Extender is a sophisticated form of negative lens [Barlow lens] used to amplify the original telescope [zoom] powers from 25-60x up to 40-96x! Which suggests it may well have astronomical uses as well as to bring in very distant wildlife subjects. More on this subject later when I have had a chance to try it more thoroughly.

Well that was disappointing! Despite using a full compensation [2.6x105mm] T-S, Glass Path Corrector on the nose of the Telescope-Service binoviewers I could not reach distant focus in the Kowa. I screwed the adapter in first and then pushed the binoviewer gently in as far as it wanted to go. It still could not focus much beyond 30'. I was at the full range of the '884s focusing knobs. Odd. I thought it might work. The ordinary astro eyepieces have plenty of inward travel to find distant focus.

Mystery solved: Despite the dealer's claims, the 2.6x GPC is not fully compensating for the binoviewer. I checked on another telescope with lots of room to focus inwards. The T-S GPC is 20mm short of full compensation. Since the binoviewer cannot be physically pushed 20mm inside the Kowa telescope it cannot possibly reach distant focus. The magnification is rather high anyway with the 2.6x GPC.

In late sunshine I had a look at a Blackbird perched on the ridge of a distant roof, at 175 yards, at 96x. Every detail of his glistening plumage was clearly visible. As were the details of his eyes. That is a truly remarkable, optical performance from the Kowa!

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9.06.2020 The Kowa TSN-884 88mm 25-60x.

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The Kowa TSN-884 is a "straight through" [ST] telescope. Which is an advantage over a "bent" 'scope for digiscoping. Firstly, the camera or smartphone screen won't reflect the sky. 

Nor will there be such a problem pointing it at a subject. As is often the case when transferring a sighting from binocular to 'bent' 'scope to camera.  It takes far more practice to align on a subject without a straight tube to sight along. Though Kowa thoughtfully provides a "gun sight" on the retractable and rotatable sun/dewshield.

The 'bent' design is often more comfortable to use and better suits people of different heights. They just have to stoop over, more or less, to look through the eyepiece. 

The "ST" 'scope would require major changes in height of tripod for different users. Or risk painful [bent] knees or standing on tip-toe. The ST also requires a much taller tripod for most users. Which means you are a more easily spotted as a dangerous human in the eyes of your shy quarry. A bent 'scope provides a lower user profile and is [arguably] less obviously human.

You might even have to raise the central pillar to make the tripod tall enough. Which risks increased vibration with a powerful telescope. Best to have a tripod which is tall enough by leg extension alone.

The Kowa enjoys a good quality stay-on case [fitted bag] in heavy nylon to provide some protection from the weather and light knocks. Once the case is fitted it is probably less visible from a distance than the 'naked' telescope. It certainly looks suitably business-like when the '884 is perched on the tripod while fully clothed.

The delightful 2-speed focuser is provided with a cover patch. While a "nose bag" protects the eyepiece. Being attached by two lanyards with Q/R buckles to the carrying trap and several poppers for extra security. All very well thought out.

My only criticisms, so far, relates to "the fitted bag." I really can't see how it becomes a "case". Which, one would assume, refers to a stiff box.  Rather than cloth.

The tripod aperture [in the bottom of the stay-on bag] has a permanently attached cover with Velcro on only one side. When the cover patch will never be used once the 'scope is permanently attached to a tripod plate. The dangling flap only gets in the way because it hangs down precisely where one wants to mount the telescope on the tripod.

I shall probably unpick the stitching of the tripod aperture patch and put it "somewhere safe." In fact it took me all of 30 seconds to remove the flap using a stitch picker. Leaving not a trace of its having ever been there. Now the patch/flap can no longer get in the way when mounting the telescope on the tripod head.  Furthermore, the patch/flap no longer blocks access to the friction knob on the '500 head.

Meanwhile, the focus knob "patch" cover [on the top] is fully removable and has Velcro strips on either side. Presumably to allow free access to left or right handed users. Might a lanyard have avoided loss of the focuser patch in the wilds?  I can slip it into the tripod carry bag. Ready for immediate use should the weather change.

The cloth cap over the objective [the large front lens] is zipped and covers the plastic, protective plate [or the bare lens.] I expect the cap will become more floppy with time. Though I would really have preferred the cap was fully detachable. Or less well attached.

A popper is provided to hold the cap back but this is very oddly fixed off-centre. Causing the circular, cloth cap to be twisted very awkwardly when hanging down. It also makes it very difficult to find and close the popper. A very odd arrangement. Completely out of keeping with every other detail so far.

A bit 'clumsy' for my tastes. So I shall probably just leave the cap dangling down when using the telescope. The zip running round the cap is very smooth in action.  I had imagined it might be a struggle but it really isn't. A pleasant touch of thoughtful quality.

I shall consult The Head Seamstress of The Household to see how the cloth cap might become removable. [Or not, as the case may be.] The expert opinion was that it would require a new, open-ended zip. Plus lots of fiddling to allow complete removal and easy remounting of the cloth cap. Best avoided.

So I will leave it well alone and let the cloth cap hang free when it is not closed. Though I may well remove the ugly white label inside the cap which makes it look very untidy. At this level of expenditure and manufacturing quality one expects these small details to be properly attended to. Even a coloured cloth label woud have helped. White simply jars the senses. Otherwise, I really like the stay-on bag for its overall neatness, excellent finish and functionality.

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