Cooling Down My Scope - Lenscap On or Off?

[bigglesdad]

This may seem like a silly question, but when I put my scope out to cool down should I also take the lens cap off the end? I have been leaving it on, but does that slow down the process? I also wondered, if I've left it on and then I take it off will the glass steam up straight away cos it's warmer than the surrounding air?

[Steep]

leave it on, you never know what's likely to fall out of the sky when you're not looking.

[Cunhaval]

Not silly at all. What I've been doing is, remove scope cap, put dew shield on (homemade from camping mat), & place outside with scope horizontal. No dew problems - works for me!

Of course, my scope is stored in a coolish place to start with.

The body of the scope is likely to get dewed during the course of viewing anyway - as long as the dew stays off the lens, I can live with that!

[bigglesdad]

Cheers Cunhaval. I made a dew shield from a camping mat yesterday, so I'll try your method on the next clear night....whenever that may be!!

[keef_uk]

sorry to hijack this thread, but think I am going to make a dew shield. Does it matter how long its made? (to fit a 102SLT)

[bigglesdad]

Reading other threads it should stick forward one and a half times the width of the scopes diameter. Mine is a 5 inch, so the shield should go out 7.5 inches. As my measurements weren't up to much mine is 10 inches!

[Moonshane]

I have newtonians which are open tube designs of course.

I leave my scope outside to cool and with the tube about 45 degrees with the top cap off, the theory is that heat rises up and out the tube. never had any problems. condensation works the other way round generally when you go from cold to warm not warm to cold.

[RikM]

Not silly at all. What I've been doing is, remove scope cap, put dew shield on (homemade from camping mat), & place outside with scope horizontal. No dew problems - works for me!

Works for me too, that's exactly what I do.