Cool Down - what is it exactly?

[LoopyLunar]

I understand that the bins need to get to outside temperature and will need some time to get to this sate - is this what Cool-Down is?

[Pete Presland]

it certainly is, it would not stop me using them while they cooled down though!

[JamesM]

The same with refractors (more a problem with the larger scopes) A good tip is to leave the diagonal off the back and tilt the scope so that the focuser is higher than the front of the scope to help the 'warmer' air escape. The same with reflectors where warmer air supplied by a warm mirror then sits on its reflective surface creating a thin thermal layer to look through and hence the difficulty in focusing at the eyepiece when the scopes first brought outside. Cooling takes far longer in 'closed' systems like binos and cassegrain/maksutov type scopes.

James

[LoopyLunar]

Cheers it makes it clearer, pardon the pun I hear alot about dew shields - I guess these are more for scopes though, not sure how they work to be honest - I will just let my bins cool down

[romanmick]

I always thought it was what the other- half tells me to do when I am in the Astro-shop

[LoopyLunar]

[scogyrd]

I hear alot about dew shields - I guess these are more for scopes though, not sure how they work to be honest - I will just let my bins cool down

I think that one of the main advantages of using dew shields with binoculars is that they keep stray light off the lenses and can help improve contrast, especially if you live in a light polluted area.

I made a pair similar to these, although I lined the inside with felt instead of painting it, for my 20x80s.

Dew Shields for 20x80 Triplet Binoculars - IceInSpace

[LoopyLunar]

Excellent looks very handy! thanks

[LukeSkywatcher]

I take my 20X90 bins outside and use them right then and there. They dont need any cooling but they can become misted up within an hour on COLD nights.

I have made dew shields for them out of camping mat and velcro which helps.