Dealing with dew on eyepieces etc?

[LittleSkink]

we (my 9yo with my help/enjoyment too) have only had our 100P since Santa came and have seen some cool stuff already - until last night when the eyepieces simply wouldn't stop misting up

It was just below zero so I put the telescope and eyepieces outside at c5pm. At 7pm everything was dripping wet (worse than previous evenings) - the eyepieces and secondary mirror were well misted so I left things another hour, and then another hour - but couldn't seem to get the eyepieces usable

Tried wiping them, warming them in my pocket and waving them about (I knew if I blew in them it would be even worse)

Jupiter could have been amazing but all we could see was a fuzzy disk

So what did I do wrong - or what can I do differently? One thought is to put the eyepieces in a tupperware box before putting them outside so they cool without gathering a ton of moisture

[dweller25]

Here is what I do.....

1. keep the eyepiece capped when not in use.

2. When the eyepiece does fog over remove it from the scope (cap the focuser), then just hold the body of the eyepiece in your hand with both ends open to the air and slowly wave it to remove the dew.

Hope that helps

[Tinker1947]

I use a hairdryer medium heat setting, to warm the EP's as i want to use them, don't use a mains hairdryer  outside, the heat from your eye will cause them to fog up if there clear but cold.....

[Floater]

Hi, LittleSkink.

It would appear the gods decided that before being allowed to view the heavenly wonders, we mere mortals must be made to contend with all sorts of difficulties and challenges.

Clouds, rain, wind, light pollution, air turbulence, numbing cold, scope stability, stumbling in the dark, costly equipment ...

I could go on but you get the picture, I'm sure

- and now you've discovered the delights of dew!

p.s. The Clear Outside app/website will indicate a 'dew point' along with the forecast, which may help you to be forewarned and forearmed?

[Charic]

I tend to leave my telescope  and oculars outside cooling for 1 hour minimum, prior to viewing.  I've found that most, if not all the thermal disturbances are firmly reduced when observing straight away at my  lowest focal lengths.

If there is still a major disturbance, or Dew is forming, the scope goes back inside, as there's always another night to observe.

[rwilkey]

Hi LittleSkink, it is fine to let the telescope cool down to the ambient temperature, but you DO NOT need to do this with eyepieces, they can be kept in your pocket or your ep case until you are ready to use them.

[ronin]

Simple:
Tell the 9yo it is all their fault :eek:  and they have to stop breathing within 20 feet of the scope. :rolleyes:

[Astro Imp]

Hi LittleSkink, it is fine to let the telescope cool down to the ambient temperature, but you DO NOT need to do this with eyepieces, they can be kept in your pocket or your ep case until you are ready to use them.

Yes and keep the case closed.

[cotterless45]

Very often if there's that much dew around , observing can be pretty rubbish with humidity in the atmosphere picking up and scattering light,

Nick.