Cooling Down The Mirrors ?!

[jamesFSO]

Hi,

I was just wondering, before I image I leave my scope outside (its a C9.25) for about an hour.

However does it make any difference if I leave the end cap on or off for the mirrors to cool down ? ...

If I leave it off, then sometimes I get dew and then have to blow dry it off which kinda defeats the object.

thanks!

JJ

(SteveL Edit: "Dew" not "Jew" )

[Taff]

The scope i have got is a 8'' reflector i puts it outside about 3 hours to cool down with the caps off.But if the mirrors are misted over i do use a hair dryer.Taff

[John]

Hi,

I was just wondering, before I image I leave my scope outside (its a C9.25) for about an hour.

However does it make any difference if I leave the end cap on or off for the mirrors to cool down ? ...

If I leave it off, then sometimes I get dew and then have to blow dry it off which kinda defeats the object.

thanks!

JJ

(SteveL Edit: "Dew" not "Jew" )

I used to leave my C8 with the diagonal out and pointed upwards (ie: with the scope pointing towards the ground) to allow the warm air to escape from the tube more quickly.

I would think that a 9.25" SCT would need a couple of hours to fully cool.

You really need a dew band / dew sheild or both to use a SCT in our climate - that front corrector plate attracts the dew so quickly !.

John

[SteveL]

With the baffle on the SCTs going almost all the way down, pointing the OTA down to allow the warmer air to escape isnt quite as effective as we would like.

Also, I had a battle with a small spider that had set up shop inside my C8 after I left it cooling with the cap off. Cobwebs everywhere (and lets not talk about the 100,000 light year wide spider that appeared whilst viewing M31!). I was just lucky the OTA was Fastar compatible, so I could get at the little blighter through the secondary holder.

[John]

With the baffle on the SCTs going almost all the way down, pointing the OTA down to allow the warmer air to escape isnt quite as effective as we would like.

Also, I had a battle with a small spider that had set up shop inside my C8 after I left it cooling with the cap off. Cobwebs everywhere (and lets not talk about the 100,000 light year wide spider that appeared whilst viewing M31!). I was just lucky the OTA was Fastar compatible, so I could get at the little blighter through the secondary holder.

Good points Steve - scrub the idea of pointing the tube down then JJ.

I think you can get specially designed fans that fit into the eyepiece holder and circulate the air more quickly to aid SCT cooling - might be worth looking out for ?.

John

[SteveL]

NS8GPS with my Cat Cooler from Lymax

http://www.lymax.com/sct/how.php

[Talitha]

Hi JJ the Lymax is a wonderful time saver for my 8" SCT. Before getting it a few years ago, I used to leave the end cap off and lock the OTA in a horizontal position when I was in a hurry to cool the scope down. Thankfully nothing ever crawled in, although a small Chickadee was perched at the opening once. It was early Spring and the bird was probably 'scoping out' nesting cavities.

[Tiny]

Just think - if over here (UK) a bird did go in you are only allowed to disturb it between November and January. Such are the nesting disturbance laws now.

I assume that cooler does not blow dust into the scope as I notice a filter on the end. Are they sold in this country?

[Talitha]

Thankfully, the Chickadee never actually went into the OTA. I was 5' feet away from the scope and when the bird saw me move it flew off.

No idea if the Lymax is sold outside the states.

There have been ongoing discussions regarding whether or not it could force dust, moisture or pollen into the OTA despite the filter, but to my knowledge no one (including myself) has ever had a problem. That being said though, the potential is definitely there. But if you're aware of present conditions and use common sense you'll be ok.