Since I started offering the Horizon in late 2012, questions regarding the Horizon design and the differences between our standard LE structures have been asked many times. The article below will help answers these questions.
The Horizon story began many years ago when a person commented that my LE scopes were nothing more than an aluminum version of a traditional wooden truss Dob. Let's just say that comment irked me a little, but not for the reasons you may think. I believe my LE scopes are a little more than a traditional truss scope. I also believe that the fact theyíre made from aluminum pushed the design into a new categoryÖbut thatís a story for another day. Truthfully, I was irked because basically he was correct. My LE scopes use the same mirror box design, same half round altitude bearings, etc.
I started building truss scopes in the late 90's. Early on I knew I wanted to build scopes for people. So when I considered a design that I intend to offer to the public, I went with what works. The traditional, simple truss tube dobsonian just flat out works, thereĎs no denying it. Itís why the design has been copied over and over again to this day.
Since I truly enjoying the challenges of designing and building telescopes, itís no mystery that a comment like this would intrigue me to think outside the mirror box. I wasnít looking to reinvent the wheel, I just wanted to change the design enough to offer an alternative to the traditional truss dob look. If you look at a square mirror box dob and eliminate the mirror box, increase the radius of the altitude bearings so they extend past the primary mirror and cell, lower the rocker box side walls accordingly, basically you have the Horizon. Over the years, Iíve seen many different versions of this type of design and I've always liked the different look it offered. I started playing around with the design, adding in my own touches, and the end result was the Starstructure Horizon. The name Horizon came after I completed the first working prototype. I moved the optical tube assembly all the way down, looked at it and said to myself, ďMy goodness, itís on the Horizon."
So you there have it.
Differences between the Horizon and LE Starstructures
The first and most obvious difference between the two scopes is the look. At first glance, the Horizon has this strange bent appearance thatís makes you do a double take. Itís not until you get close and see the primary mirror placement that things start to make sense. In my opinion, the Horizon has a smoother, softer, seamless look than the LE. The rocker box and mirror box appear to blend together. Itís not until you move the optical tube assembly that you realize they are individual pieces.
Next is the overall size of the scope. Horizonís mirror box sides and altitude bearings are one and the same. This arrangement eliminates the altitude bearing thickness from the overall width of the mirror box. As a result, the Horizon mirror box and rocker dimensions are smaller by as much as 3" in width depending on size. The larger altitude bearing radius contributes to the Horizon having a much lower rocker box. The lower rocker walls cut down on the amount of side to side deflection. This lowers the ground to altitude bearing tip height by as much as 5" depending on scope size.
The top of the mirror box on the Horizon (when at zenith) is angled down to the back of the scope 32 degrees. As a result, the opening on the top of the mirror box is oval instead of round. However, when you look at the opening from the front of the scope through the UTA, it will appear round the same way the secondary mirror looks when viewed through the focuser. The oval opening is larger and allows rising air to escape the mirror box more efficiently. This contributes to faster equalization and considerably less tube currents.
Another major difference between the scopes is the truss tube lengths. Because the mirror box has an angled top, the truss tubes are not the same length. The front four are shorter than the back four. A positive to this is that the trusses can only be installed one way. This assists tremendously with accurate repeatable assembly. The light shroud on the Horizon is a bit strange at first. It is cut to match the mirror box angle so it can only be put on one way.
Unlike the LE design, the mirror cell is NOT removable on the Horizon. The primary mirror is installed and removed through the oval opening at the top of the mirror box. The larger oval opening gives you ample room. On larger Horizons, the entire top plate of the mirror box is removable to give even more clearance for mirror install / removal.
Because the primary mirror and cell are located inside the radius of the Horizon's, mirror box the Servocat altitude motor can be mounted inside the rocker width dimension. This makes the Horizon 2.5Ē narrower then the LE with a goto drive. The location of both altitude and azimuth motors are on the opposite side as compared to the LE so the disengage levers are also located on the opposite side. The Servocat control box is mounted at the back of the rocker on the Horizon as opposed to the focuser side on the LE.
The weight difference between the LE and Horizon is minimal for sizes 22Ē and up. Only 5% +/- differential and not worth mentioning. Horizon sizes smaller then 24Ē can be up to 20 pounds heavier then the same size LE depending on focal length.
In conclusion, The LE Starstructure is a time tested design so almost all of the major components are incorporated into the new Horizon unchanged. A list of these components from top to bottom includes: The entire upper tube assembly (UTA), focuser board, secondary holder and spider. Truss tubes, light shroud, mirror cell, and the ground board are also unchanged. Although the scopes look different, the LE and Horizon designs load, transport, assemble, collimate and view the same way.
Keep looking up,
HORIZON VS. LE