[mick pinner]

after reading Mikes thread about his new scope and congratulations by the way, and then Ezy's thread regarding his NGT 10" and guidscope congratulations again they were both refering to their concerns regarding weight and l started to think, and this is where l am probably stating the obvious to most but the newbies may get something out of it, weight to a point is not the overriding issue it is where it is placed that becomes the problem.
l am not sure how the manufacturers come to their ratings and exactly what parrameters they use to get there but lets assume they calculate it along a line that runs parallel to the dovetail and say 125mm above it, a 250mm scope at f/l 1250 maybe under the load limit along that axis but adding say an ED 80 guidscope the axis of the guidscope may be 350mm from the balance line and this will, due to the cantilever effect make the ED 80 in effect weigh twice as much as it really does.
A long focal length Newtonian weighing the same as a short focal length scope will in fact present more problems when it is on the mount because you are moving the weight further fron the balance point, the dew shield on my Meade weighs around 600 grams but it takes 3 times that ammount of weight to balance it.
What weighs say 12kg in your hand could have the effect of weighing twice that when it is loaded because of the motors having to drag the weight through a greater arc than it was designed for.