DEW PREVENTION

[HippyH]

Hi all,

I'm new to this site so forgive me if this is a repeated question

I have just bought a 200p/HEQ5 Newtonian scope and would like advise on proper placement of dew tapes for the Primary mirror and eye piece.

Should the main tape be on or in front of the mirror cell? How close to the eyepiece should the 1.25" tape be?

Thx in advance

HippyH

[swamp thing]

Hi Hippy

It is very unlikely that your primary mirror will get dew on it.

It is well protected being right down the optical tube. Which is acting as an extra long dew shield.

The secondary on the other hand will benefit from a dew tape wrapped around the edge of it ( take care not to touch the reflective surface).

Alternately make a dew shield this will work too.

I have both systems on my larger Dob. Better safe than sorry.

I find the 12v hair dryers work best for keeping eyepieces dew free.

Regards Steve

[JamesM]

Hi Hippy and welcome to the forum.

Newtonian scopes don't need dew prevention as the mirror is at the bottom of the tube and well protected from dew. The eyepiece can be protected by simply placing the plastic lens container that it came in over the top of the eyepiece when you are not observing. You might consider making a dew shield to extend the front of the scope to help keep out stray light and to offer some protection for the secondary mirror that could attract dew if you are out for a long time. Don't buy a dew shield but instead make one out of a length of camping mat (Tesco sell them for £1.50) and make this dew tube so that extends about a foot beyond the top opening of the scope. You might want to make a baby dew shiled out of the same material for your spotter scope too!

One of the many virtues of the reflector scope is that it is not a dew magnet unlike refractors and cassegrain type scopes because they have a cool surface at the front.

Hope that helps

James

(P.s Steve got there before me - must learn to type quicker!!!)

[HippyH]

Thx James and Steve for replies and welcome.

Erm Does any1 want to buy an 8" Dew tape ? Lol

[swamp thing]

Thx James and Steve for replies and welcome.

Erm Does any1 want to buy an 8" Dew tape ? Lol

Afraid not, my secondary's not that big.

[JamesM]

If it could be used to keep my other half quiet then YES - but I fear I will need more aperture!!!!

James

P.S So easy to be brave when she's not looking!

[HippyH]

If it could be used to keep my other half quiet then YES - but I fear I will need more aperture!!!!

James

P.S So easy to be brave when she's not looking!

HAHAHAHAHAHAHAHAHAHAHAHAHAHAHA!!!!!!!!!!!!!!!