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DEW! :(

Gloris

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Gloris

Gloris

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Just been up to west wycombe to try my new 8"dob, and while it was darker, and the skies clearer than my back garden, the experience was somewhat dampened (pun intended) by my first encounter with the enemy that is known as dew. It left stunning views of Jupiter in a sort of cloudy haze, and I have come home and looked inside the scope to see my main mirror absolutely soaked. Is there an easy way to counter this and is there anything I should do now other than leave it to dry? Is it safe to even keep using it tonight despite the haze, what should or shouldn't I do?

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sunshine185

sunshine185

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The mist on the primary is probably due to bringing it inside, it is more than likely your ep's that heave misted over.if you are staying in, just leave the dob horizontal until it has cleared, if you are going back out I would do the same, leave it horizontal until the primary clears. It has been said that keeping the ep's at slightly above outside temp can help with them misting over.

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Gloris

Gloris

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Okies, I'll do that for next time, or possibly just invest in a dew shield...but how about right now? Should I just leave it inside to warm up? Should I point it up or down? I'm at a loss as to know what to do to clear the mirror.

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Gloris

Gloris

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Ok, thanks....think I'm gonna call it a night, LOL. Frozen to the bone from being at such higher altitude LOL (i make it sound like a mountain, its just a big hill). It has started to clear but there are still huge patches of water. Quite scary, being my first major scope, but I assume they think of things like this when they make them, so it won't actually damage the mirror? I just need to be patient and wait for nature to do its thing and clear it?

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John

John

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Just leave the scope overnight and the optics will clear. It's bringing cold glass into a warmer environment that does it. By all means wipe the mechanicals down but don't touch the optics !.

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Gloris

Gloris

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right, went to blacks today, got myself a 9mm thick camping mat, totally black :)

got some stick on velcro from wilkinsons.....now for the construction....any tips?

i must say, i'm a tad confused....all the pics i've seen show the dew shield fitted to the open end of the scope.....but i'm not sure how well it will stay on, as i've only got around an inch an a half at the end of the skyliner 8" dob before you get to the adjusting screws....how to people get around this?

do you just fit it literally to that inch and a half? or cut circles where the screws are? or cut grovves and just slide it on?

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Gloris

Gloris

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Make cut-outs for the adjusting screws so you get 3-4" on the tube....

cool, thanks.

i've cut out for the screws, and it's on about 3" now. feels quite sturdy. I'll try it out tonight, but if it doesn't work out i still have enough material left to try again, and maybe i'll cut around the focuser and finder...but for now this will do as a first attempt :)

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todd8137

todd8137

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well if it was put in the car as i take it ,the heat in the car would have added to this and made it mist over ,not sure how you transporting itnot vertical in any way i hope can you not pack it out with pillows at 45 degrees ?a couple a sleeping bags and pillows normalyy does the trick for me,i always leave the cap on in the car theres a lot of dust floating about in cars a cheap 12 volt hairdryer some a camping and caravan type one,and as suggested a diy dew shield, cheap 4" pc fan and a sheet of plastic and some glue you could make a fan that fits at the big mirror end and a rechargeable batt of some sort thats what i do never had dew since just thick coats of ice , i always rub the outside of the tube down bags of silca gell 20gram bag ones to soak any damp out

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Gloris

Gloris

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yes, my dad suggested the same thing. when me and my brother transported our scopes to west wycombe, we did have the heat cranked up on the way, and on the way back (especially high on the way back too).

anyways, so far so good....nice cloud free skies here tonight....seeing still isn't as good as i've seen though. but anyway, the dew shield seems to be doing its job, i can't see a single drop on the primary for sure...nore anything on the outside of the tube.

one thing i am noticing though, is that i think my eyepieces are misting up occasionally....sometimes to the extent that every bright star has a misty cloud around it, and sometimes sort of, "lightening bolt" style streaks of light surrounding it....however, if i move away for a bit, leave the eypiece be, it soon clears up again.

maybe just because it's so cold out, i'm breathing more heavily or soemthing....hot air + cold optics = mist? :)

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Gloris

Gloris

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i actually am starting to think i might have just been a bit too close to the eyepiece as well...since i've moved my head position back a bit (only slightly mind), i've found that the eyepieces are not misting up....tonight i've also discovered the benefit of staying focussed on one particular object in the sky for a while...just spent the best part of an hour looking at the nebula in orion, and by the end the view was stunning, i really could make out the shape, where previously i'd just seen it as a "sort of cloudy" area. Also found out that if you're enjoying a view like that, DON'T REPLY TO YOUR PHONE :)

I looked at it's bright screen for only a few seconds, looked back to my scope and the shape and detail was completely gone...my eyes just lost their dark adjustment, like that, in an instant...another rookie mistake...it's just started to cloud over so i've come in to wam my toes for bit before heading back out, hopefully moon will be out soon so i can have a look at some more of the details there.

only got my dob a few days ago, and i am so impressed. totally new to astronomy, but this is all fascinating...it really makes me wonder why i didn't ever consider this as a hobby before...

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M4lcs67

M4lcs67

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Me too. Thank goodness I did have my dewsheild on, but the whole setup had a lovely film of frost on it tonight. Brass monkeys or what. Luckily had my duckdown jacket, hat, scarf and gloves on tonight. Crystal clear here in Yorkshire. Just hope it holds out for the start of Stargazing live on Monday.

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Dunkster

Dunkster

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A couple of (capped) EPs stashed in jacket pocket works a treat! I'm still learning (forever!) but narrowing my EP choices down more or less suitable to the objects I have on my plan - so only a couple in the pocket, one in the diagonal.

My dew shield held my 6 up for 3 hours tonight, and I'm OK with that. Maybe a heater would help :)

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