Markless™ Counterweight System is a sliding, adjustable system which can be used to quickly re-balance your Obsession® Telescope (or almost any other Dobsonian mount Newtonian reflector truss telescope) when you have changed eyepieces, and/or added/removed something from the Upper Tube Assembly (UTA). The barbel weight typically used (2.5 lbs. for larger scopes) is not included because it costs more to ship than its purchase price at Walmart™!
The system consists of a front sliding counterweight and a rear sliding counterweight. Both are necessary due to the need for the center of gravity of the system to aligned as closely as possible with the mechanical axis of the OTA. Doing so ensures that the scope will be balanced at any angle of elevation. In practice, one would split the total sliding weight between the MCW and the FCW. For example, if you used 5 pounds of sliding weight, you would put 2.5 pounds on the MCW and 2.5 pounds on the FCW. Most of the time, you would not need to adjust the position of the FCW weight.
The FCW will require two or three #8 screws (supplied) for mounting. The accompanying photographs show the FCW (and the RCW) in place on a 12.5” Obsession clone. They have 1.25 pound weights attached. Different sizes of FCW/RCW systems are available for each Obsession size and any other big truss tube Dob, so please indicate your Obsession model or your telescope's mirror box dimensions when you order.
The Rear Counterweight (RCW) is very similar to the FCW in style and construction. Like the FCW, the RCW is not "markless". It mounts with stainless steel sheet metal screws. However, the RCW has a safety cable since the top of its track extends toward the opening of the mirror box.
I have located an excellent source for the weights and they have all of the small sizes (down to 1.25 pounds) in gray, black, and even chrome! Write me for the link when you order.
North Carolina residents please add 7.25% sales tax.
To order, or for more information, email me at cs(at)marklessastronomics dot com
Charles Starks, Charlotte, NC
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Astrocrumb Filter Slides - a "MUST HAVE" accessory for your Big Dob. Roger builds 'em RIGHT!
Copyright 2003-2015, by Charles Starks, Charlotte, NC, All Rights Reserved
Updated: 4:51 PM 11/23/15