Dew is less likely to condense on a reflector's mirrors in the night air, an annoyance with the other designs unless they are provided with a long dewcap
The generously long dewcap
is secured with two locking screws, so it won't slide back down the tube with a bang when aimed straight up.
Any telescope in bright local lights should also have a long dewcap
to keep stray light out of the tube.
But just 15 inches (38 cm) long with the dewcap
retracted, the TMB tube is as short as some 80-mm apo refractors.
The retractable dewcap
is a nice touch, and it never slipped or sagged in use.
This happens only with the SD because its foot is reversed relative to that on the other scopes to allow the dewcap
to fully retract (the SD has the shortest tube).
A sliding dewcap
extends almost 2 inches beyond the objective.
6-kilogram) tube measures 16 3/4 inches (42 1/2 centimeters) long with the dewcap
and focuser retracted.
The felt-lined dewcap
retracts completely for storage but slides forward to add 312 inches of extension to keep dew off the front element.
But at 28 inches (71 cm) the tube is longer than it needs to be for storage or transport because the 6 1/2-inch-long dewcap
does not retract as with most other high-end refractors.
With a tube only 14 1/2 inches (37 cm) long when the dewcap
is collapsed and weighing only 4 pounds (1.
With their exposed front lenses, a dewcap
would be useful for the Meade scopes.