Telescope Reviews: Report: Sky Window Mirror Mount

Report: Trico Machine Sky Window (TSW) - binocular mirror mount.

I'll have a first light report as soon as I get enough clear skies, and a bit of experience with the sky window. This report is about the TSW itself.

Disclaimers:
1. I am not affiliated in any way with Trico Machine or any of its owners or employees.
2. This report is entirely my own opinion based on my personal knowledge and needs, with my specific unit. Your results may be different.

Background:

I have arthritis in my hips and back, making standing and bending difficult, and often painful. While I enjoy using binoculars for astronomy, I do not enjoy "paying for it" with pain and stiffness for a full day afterward. Hand held views were not satisfying because of my personal shakiness -- I can not keep 7-8x binoculars "rock steady" for more than a minute. 10x and up are simply unuseable hand held. A tripod steadies the view but forces me into painful positions, and viewing above 45 degrees to the zenith is worst of all.

I spent hours sifting through user and builders reports for p-mounts, special binocular chairs, tripod configurations, etc. The Cloudy Nights members are nothing if not resourceful! Unfortunately, none of these mounts actually solved my problem, until I discovered the Trico Machine "Sky Window" mirror mount.

From horizon to zenith, the binocular eyepieces do not move, ie. it is not neccessary to raise, tilt, or lower the TSW to reach the eye-pieces regardless of the altitude you are viewing. This provides a comfortable seated position similar to reading a book laid on the table.

It took me several weeks to take the plunge, and order the TSW. This unit is fairly expensive, currently the basic unit is $259.95. Mirror upgrades add another $35 for the silver level, $70 for the gold level mirror. I called and talked to Jim for a few minutes and he recommended the silver upgrade mirror for my uses. I discuss the mirrors further down in this report. In addition to the mirror upgrades, there are threaded adapter rods available to fit a variety of binoculars, including Canon IS, and the Celestron types with the center rod mount. Trico Machine sells a 9x60 binocular for those that need one. There is also a green laser pointer and holder availabe for use as a finder.

Out of the Box:
It took 3 weeks for my TSW to arrive. The delay was due to my timing --- they were out of tested upgrade mirrors, and Jim was waiting for the night skies to clear enough to do the needed star tests. Finally, The Box appeared on my front porch without any sign of damage to the packaging. My hopes for an intact TSW increased futher when I noticed the large red "Fragile" & "handle with care" tags and firmly attached strapping tape. Upon opening, the usual pile of styro-peanuts erupted across the floor to reveal the mirror and mirror tray undamaged within its bubble wrap. The package also contained a plastic bag of hardware, three hard plastic cup feet, the mirror mount base, the upright, and a set of instructions.

I tend to be very cautious with assembly, I've messed up a number of such tasks before, so assembly took 10 minutes. I suspect most folks could do it in under 2 minutes, it is very simple and obvious. Assembly only requires attaching the upright to the base, inserting the binocular attachment bolt, and setting the mirror/tray unit into the slotted uprights in the base. Obviously, you would reverse the assembly to break the TSW down for travel in a (user supplied) case.

The first impression of the TSW was "man this thing is heavy!" The spec sheet lists it at 7 pounds (3.2kg). The weight is due to the machined solid aluminum bar stock used to make the TSW, no sheet metal stampings here (except for the mirror cover). The machining is top quality too. There are no rough spots, burs or tool marks visible. All assembly screws were tight and properly aligned (no tilted screw heads), squared edges were square and lightly polished to remove any sharp edges. The slot in the base that accepts the upright was just large enough to fit the upright without wobble or binding ( no small feat, try it yourself sometime). All visible threaded holes were cleanly cut without signs of "false starts" or recutting, and fit the threaded bolts perfectly just as they should. Trico Machine could teach the manufacturers of metal patio furniture a few things about accuracy and precision. This is a quality product. (thanks to my late father - a master machinist- for teaching me what quality machining should look like. He'd be pleased with the TSW, I'm sure.)

Set up

I mounted my Pextax 8x40's to the TSW and discovered a problem. The 1/4x20 attachment bolt was slightly longer than the depth of the female threads on the binoculars. This results in less than 1/4 inch (6.3mm) of bolt extending beyond the bottom of the upright, and more importantly, allows these binoculars to rotate freely around the center post axis. However, in use this posed no problem at all, the binoculars self-center and stay put unless I grab hold. I did notice the 8x40's brass(?) mounting thread plate and the TSW upright were being marred by their rubbing together. I bought a 1/4 inch thick nylon washer, and inserted it between the binocular and the mount upright. The washer allowed the binocular to mount firmly without spinning. This problem did not exist with my Nikon 12x50 Actions.

Next I aligned the binoculars with the center of the mirror. You rotate the mirror to both extreme positions (ie zenith or horizon position) and see if the mirror tray edge shows. If so loosen the bolt holding the upright in the slot and slide the upright forward or backward until only the mirror shows in the binoculars. It takes less time to do than to write it down.

At this point I was ready to view, but it was mid-day with heavy over-cast. I went outside and set the TSW on the patio table (heavy, stable, iron, and ceramic tile top). The three rubber feet clung to the table top without any slippage, not even when I tried to slide it. While you can force it to slide in this configuration, its a lot easier to just pick it up. I do know I could have put the plastic cups over the rubber feet if I really wanted it to slide, but I didn't bother.
Also, with my two binoculars there was no hint of instability, nor did it seem at all top-heavy. I suppose you could mount a binocular that was too heavy, but I can't comment on that.

The seven 1/4x20 threaded holes on the tripod adapter plate allow attaching at, or at least very near, the balance point for my two binoculars. The quick release plate for my bogen 3-way quick release head attached with no problem and did not interfere with setting the mount on a table.

With no stars to view and a blank grey sky, I rotated the mirror to view the top of a willow tree across the yard. Not exactly a "stellar" first light... except birds suddenly glided across my field of view a moment later (really!). Given the lack of other viewable objects, and no real sense of the quality of star views in the mirror, I packed the TSW back inside.

At that point it hit me! I had gone outside and back in carrying the complete kit in one hand, while using my cane in the other and had given no thought at all to the weight, my balance, or any increase in my pain level. Such a small thing to most of you, but to me this is huge.

Details, Details

It's the little details that make the difference between a quality product that is easy to use, and one that is merely adequate. The TSW is quality even in the details.
1. The tripod mounting plate has seven 1/4x20 threaded holes. Each hole is numbered with large readable text, and these numbers are machined into the mounting plate, not painted on. Your great grand kids will still be able to read these.
2. Knobs are either large plastic ones with good grip, or machine knurled patterns- either flat-topped diamonds or fine vertical lines. All three provide a good grip with my fuzzy wool gloves.
3. The upright that holds the binoculars is shaped like a large wave pattern that fits your gloved fingers for a secure grip when carrying the unit. It could have been a plain straight bar, but somebody thought this out very well indeed.

The Mirror

The mirror is the heart of this system. The mirrors used in the TSW are made from float glass. These are not true optical flats, as gravity is the "flattening" agent. Float glass is made by floating molten glass onto a "bed" of molten tin (usually), temperature control keeps both materials molten long enough to reduce stress in the glass and allow the glass to self-level. The rest of the process is not particularly important to astronomy. The final phase is coating the front surface with aluminum which is overcoated to seal and protect it.

Mirrors of this type I am told have a wave front of around 1 wave compared to true optical flats that are usually 1/4 wave or better. (experts, please correct this if I am misinformed) Obviously the optical flat is best for magnified viewing, and if you can afford $5,000+ for an 8x10 inch front surface optical flat -- go for it. The rest of us need to be aware of the limitations of our float glass mirrors -- they can not handle high magnification without image distortion. The TSW is designed, and intended as a low magnification, wide field view system. My personal decision is to avoid pushing the magnification to the "breaking point". I suspect I might try anyway, but at least I have good intentions. Trico Machine lists the maximum magnification each mirror grade is suited to: standard = 10x; silver = 15x; gold = 22x.

Now the reason I chose the middle road - the silver grade mirror rated for up to 15x. My finances have never been that great - I pushed the limit of my budget as it is .... the silver upgrade kept my finances from going into the red. Also, I have looked at specs of many binoculars with 12x and greater magnification, and my finances, my exit pupil needs, my eye relief needs, and my weight restrictions limit me to binoculars up to 15x70 for the most part. I would have liked the gold upgrade, but ...

The bottom line:

If you want maximum magnification, the TSW may not be for you. If you are willing to stay within the limitations, I think it is a very good choice. Also, if you decide to buy a TSW, try it, and don't like it - Trico has a 30 day return policy.

Positives
1. quality of build
2. compactness, and portability
3. very comfortable viewing even for people with physical problems
4. a specialized, wide field, low power viewing system. Excellent views of the Milky Way, etc. easy to share view with others.

Negatives
1. the mirror has magnification limits that may be too restrictive for some observers
2. the price, especially when you add upgraded mirrors, binoculars, adapter, laser mount, and laser.
3. a mirror image, which shouldn't matter viewing the heavens, but can be disorienting at first.
4. limited to a specialized, wide field, low power viewing system. Not suited for some astro objects and no way to "convert" it for high magnification use.

I hope this was helpful. It will probably be 4 to 6 weeks before I can give a viewing report. That may be optimistic given the weather, smoke, etc around here. Please Stand By

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Nikon 12x50 Action; Pentax 8x40 PCF WPII
Bogen 3220 w/3way+qw
Trico SkyWindow