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MIRROR CELL:  One of the most critical parts of a telescope is the mirror cell.  Whether the mirror is flat on its back when the scope is pointed at zenith, or almost vertical when pointed at the horizon, the mirror cell has to support the mirror perfectly.  Even the slightest deviation and the image at the eyepiece suffers greatly. 

Computers have been designing mirror support systems as long as there have been computers.  But it took David Lewis to design a program called PLOP that revolutionized the layout of the cell. What makes PLOP so different is that it takes into account the type of glass, the thickness of the glass, the focal length of the mirror, the obstruction size of the secondary mirror and a host of other factors not accounted for in old, simple "spread out the load" programs.  Even though PLOP has been available for many years, most telescope manufactures have never updated their ancient cell layouts. 

Knowing where to place the support points is only half the battle.  The actual engineering and execution of the support system is the hard part.  If you take a look at the other commercial mirror cells out there, they "balance" the load of the mirror by just laying the cell parts on machine nut heads.  The parts just rattle around on the six sides of the head!  Our mirror cell parts float on hardened, American made stainless steel bearings that ride in a stainless steel raceway lined with Teflon.  Just like an eyeball in its socket, ALL of our moving parts glide in 180 degrees of motion, with no hangups or restrictions.  We started using this system in 2003 and it has amazed all who have seen it.  I know the engineers out there are saying to themselves that these bearings would add a few hundred dollars to the price of the cell, but when you are supporting a $15,000 mirror, we believe that this is money well spent.  If you haven't noticed by now, we don't cut corners on anything!

EDGE SUPPORT: When a the telescope is viewing anywhere but at zenith, the mirror needs edge support (unless you go with our GLUE DOWN option).  Our edge support system uses a thick stainless steel aircraft cable consisting of 49 individual strands.  This super flexible cable conforms to the mirror edge, giving perfect support at precisely the center of gravity (which, by the way, is NOT the center of the mirror edge).   By ONLY placing the mirror weight at exactly the center of gravity, ALL of the resulting edge stresses are parallel to the back of the mirror.  No other sling system can do this. 

The cable can hold 1000s of pounds of tension before stretching even a millimeter.  Talk about solid support!  Industrial Velcro® holds the cable in place, yet is easily removed for service.  The cable glides against the glass surface with hardly any friction.  If adjustment is ever necessary, the cable can be precisely ADJUSTED WITHOUT ANY TOOLS AT ALL. 

Lesser "quality" telescopes feature synthetic fabric "slings" or belts that stretch or expand with every temperature change.  Kevlar ages and frays (that's why bullet-proof vests have 3-5 year expiration dates).  Anything coated with rubber, vinyl or cork expands and contracts with changes in temperature and will have much more friction against the edge of the glass. 

Band slings intrude too close to the sensitive face edge of the mirror, exactly the place we want keep pressure away from.  Because Band slings put pressure on the mirror edge outside of the center of gravity, at lower elevations, they can actually lift the mirror away from the support triangles.

Even worse, we have seen some edge supports that use 2 pegs that actually rest against the mirror edge, distorting the figure of the mirror in 2 places.

If you own another brand telescope and are starting to get that sinking feeling, don't worry, we sell our stainless steel cable edge support system as a SLING RETROFIT KIT for only $60.  We can't rebuild your entire cell for you, but we can give you perfect edge support.

18 POINT MIRROR CELL WITH CABLE SLING

AIR FLOW:  Using the strength of steel in our frames, rather than wood or aluminum, has allowed us to utilize one of the most open cell designs anywhere.  Take a look at other "quality" designs, and see how much of the mirror surface is obstructed by bars, cross members, rings, and other hobbled together devices.

LEAVE THE MIRROR IN THE CELL:  Our cell is designed so that you can just leave the mirror safely in the mirror box, where it belongs.   No need to remove the mirror every time you move the scope.  This eliminates the chance of dropping the mirror and keeps your spine out of harms way too. When you are tired at the end of the night, the last thing you want to do is walk around with an expensive mirror in your hands. You can wash the mirror right in the mirror box too!  The only time you will be removing the mirror is if you are shipping the scope, or are going to be "off roading" on some really crazy trails. 

Our mirror cells are available to the ATM HERE.

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