What size dew shield?

[lavoisier]

I have an Explorer 200P and am going to make a dew shield from a camping mat and sticky velcro. I'm just not too sure how long it should be. Any help please?

Thanks

Paul

[John]

The one I use on my 10" scope projects about 40 cm above the top of the tube. Hope that helps. I don't think it's a precise art with newtonians - mine serves mostly to keep stray light out of the top of the tube which helps with contrast as I have some neighbours lights and the odd nearby street light to contend with.

[lavoisier]

Thanks. Good to know it's not a precise science it's easier not to mess up that way.

Thanks

Paul