ABOUT OUR SHROUDS
Every Shroud by Heather is layed out, measured, re-measured, sewn, and inspected with great care prior to shipment. We use only the finest Nylon/Lycra blended materials, which in concert with elastic banding on each end of the shroud yield a light-tight enclosure around the open section of your Truss Dobsonian.
Our shrouds are not made from "kite material" and will not sag into the optical pathway of the scope. The materials we use make for a form-fitting, curve-hugging, aestetically pleasing shroud.
There are no draw-strings to break, or tie-downs that rip the fabric, or velcro and snaps that come loose on our shrouds. Simply put, each shroud is custom tailored to your individual telescope and requires no adjustment on your end. Simply leave the shroud bunched up around the bottom of your UTA and then pull it down over the Truss poles when assembling the scope.
Furthermore, water will not collect on the shroud surface and then drip onto your primary, as other shrouds allow. Instead, Shrouds by Heather allow the dew to gently soak into the shroud material and spread out, keeping drips from forming. The shroud need only be left outside the next morning for our resilient material to air dry.
WHY HAVE A SHROUD?
There is a great debate whether shrouds are indeed necessary for visual observations out in the field, and there are strong opinions on both sides. Our thinking is of course in-line with the necessity of a shroud in all but the darkest, dew-free and people-free environments.
Light Pollution: Most observing takes places in suburban observing landscapes, or at best brighter rural landscapes. Light pollution has become a factor in most astronomers' observing sessions, except for those fortunate enough to have access to truly dark locations many tens, or even hundreds, of miles from population centers. This ambient light can enter the optical pathway and reduce contrast at the eyepiece. This is particularly true for those scopes where, when looking down the drawtube of the focuser (without an eyepiece), you can see out the top of the Upper Tube Assembly (UTA) or out the bottom of the UTA, or possibly both. A shroud will help take care of light entering the focal plane from below. The same is also true for your mirrorbox, as light can potentially be entering through the open top and reducing contrast.
Moisture Control: If you have seen Schmidt-Cassegrain Telescopes (SCT) out in the field, chances are you have seen dew-caps that extend past the front of the main corrector. These help combat dew from settling on the corrector, and the same thought process holds true on Truss Dobsonians. By adding a shroud in front of the primary mirror, you are in essence allowing the scope forward of the primary to act as a giant dew-cap, keeping your primary dew-free in even the most damp of conditions.
Mirror Protection: Lastly, there's always the fear of dropping tools, eyepieces or other misc. parts next to your scope during an observing session. The same goes for people walking near your scope, especially children who may not be aware of the pricelessness of the primary mirror residing at the bottom of your open mirrorbox. For most scopes, the height of the mirrorbox is at hand-level or lower, increasing the risk of something inadvertently being dropped onto the primary. A shroud is an excellent way to seal up your tube assembly so you can have a worry free observing session.
ORDERING A SHROUD
When placing an order, please have the following measurements ready:
Top Circumference: measured around the bottom of the Upper Tube Assembly (do not include any hardware that protrudes from the UTA, unless protrusion is excessive, ie. 4"+).
Bottom Circumference: measured around the top of the Mirrorbox (do not include any hardware that protrudes from the mirrorbox, unless protrusion is excessive, ie. 4"+).
Length: from the top of the mirrorbox to the bottom of the Upper Tube Assembly when the scope is assembled.