Newton question.

[Paul Bulbeck]

Quick newbie question,  do newton telescopes have a front glass or are they open ? Wonder about dust prombles in use .

[kerrylewis]

Newtonian reflectors do not have front glass but remain open. Dust is not really a problem while in use and some sort of cover usually protects the mirror when not in use
 

SCT scopes have a mirror at the rear and a glass plate at the front but that is a different design 

Kerry

[Paul Bulbeck]

Thank you. 

[Louis D]

Dust has to be really heavy before it affects the views in any appreciable manner.  You can stick your hand in front of a large Dob's opening while observing, and the most disruptive effect will be from the heat waves shimmering off your hand in cold weather, not the actual blockage.

Overzealous cleaning of optics can lead to micro-scratches that will affect contrast by increasing light scattering.  It's generally best to leave light dust evenly coating a mirror or corrector plate rather than trying to clean it off.

[starwatcher_ch]

There exists Maksutov-Newtons (e.g. Explore Scientific MN152/740) with a Maksutov glass. With it you don't need a corrector for photography. The Maksutov glass is the corrector and of course at the same time a dust protection.

But as the others mentioned, standard Newtons are open.