Advice please -new 8" skywatcher 200 dob - condensation drip on mirror.

[PeterE]

Hi. I'm new here and have just been out for one of my first nights viewing with my new 8" dob and, as far as I can tell, the mirror has a drip of condensation on it. It also doesn't look as clean as it did when new,just a few hours ago too. It looks murky and doesn't sparkle when I peer into the tube.

So, what I need to understand is am I worried unnecessarily and it will dry and the mirror be unaffected or have I committed a sin by letting condensation drop onto the mirror? If I have,do I need to have the mirror cleaned (professionally)?

Also, I have just read about not touching or cleaning the eye piece lenses after doing both, especially as they started to fog with condensation. They don't look damaged but do you think I will now have to look at replacing them? Is scratching and damage usually quite obvious?

Thanks in advance for any advice.

Pete

[Moonshane]

hi Pete

don't worry I am sure there's no damage.

as a general rule telescope mirrors 1) look awful if you shine a light down the tube (don't do it) and 2) are pretty much unaffected by dewing and condensation if left to dry overnight. store the tube with cap off at about 45 degrees and this will stop drips falling onto the mirrors but there's no effect at all to the view. generally cleaning mirrors has no benefit and can damage the coatings so I don't generally bother.

re eyepieces, never clean when damp or in the field. if they fog up then if you fan the eyepiece with your flat hand, this often clears the dew quickly; some use a little fan or even a 12v hairdryer (a bit loud for me). if you just used your finger, then the chances are there's no damage as eyepiece coatings are quite hard. if there's a finger print then cleaning might be a good idea. I use isopropyl alcohol and soft tissue (no pressure, just the corner and chase the liquid around gently until clean). others use Baader wonder fluid but be gentle and patient.

[PeterE]

Thanks Moonshine.

I will leave the scope to 'dry' overnight and recheck but, now, worry less.

as for the eye pieces I am now wiser after the event. Thanks for the tips. I have camera lens cleaning gear - I am a keen photographer too - so will use that with caution and hope I haven't damaged the coating.

Thanks again.

I hope I have avoided expensive lessons.

Pete.

[knobby]

Don't worry Pete, Shane's right!

Just don't do it again

[NGC 1502]

Hi Pete, welcome to SGL.

Post #2 is great advice. A drip on a mirror is nothing to worry about. Just let everything dry out thoroughly before storage. Mirrors get dirty, that's normal, and best left alone until things get very grotty indeed. Don't check by shining a light down the tube, all mirrors look horrid if you do that, unless they are literally brand new.

No need to replace those eyepieces either, if they look unscratched they are fine.

Just relax and enjoy the view (if ever the pesky clouds go away )

Regards, Ed.

[Moonshane]

this http://www.petapixel.com/2011/06/16/how-dust-and-damage-on-lenses-affect-image-quality/might make you feel better. you can still get a surprisingly good image with a lot of damage and this applies pretty much to all optics in reality. we all tend to understandably 'baby' / coddle our equipment but it's almost certainly not necessary for good performance to continue.

[PeterE]

Thanks everyone and MoonSHANE (I really should learn to read - apologies!).

Here's hoping for less cloud. I have a nebula filter I am eager to try....

pete

[Moonshane]

ha ha - I've been called worse