Taking gear in and outdoors...

[NickW]

I am wondering how people handle their gear with respect to temperature changes and dew. Tonight was my first real attempt at observing. I put my scope in the porch to let it cool and then moved it to an even colder area before taking it outside where I got some good views of Jupiter with banding and moons as well as the Orion nebula. I then did the reverse but noticed that the OTA was v wet when I moved it in to the porch and examination showed the front glass of the tube to be misted (its a MAK btw).... and so to my questions...

1. do people generally make gradual changes in temperatures like I tried or do u just go straight outside and leave it there a while?

2. what about the return trip?

3. should I be worried about the misted glass - I refrained from touching and wiping it but left it open (no covers replaced)

many thanks for your guidance

Nick

[Eastridge]

Sure someone with a mak can reply more specifically but in general from what I do having followed advice on here from many:

1. Straight outside and leave for 30 mins + with caps off and tube facing slightly downwards so nothing can 'drop in'

2. Bring it in, position as 1 with tube slightly down, put caps on next morning.

3. I have never had a problem from misting ( downwards slope means nothing condenses and drips onto mirror, but that's with a Dob not sure re a mak.

[damnut]

Hi Nik,

The maks corrector plate attracts dew like flies to doggy do!!.

You should let your scope cool down, the bigger the mak the longer to leave it before you use it. This equalises the temperature of the air in the tube and improves 'seeing'. You should also do the reverse when bringing it in. Using a dewshield will provide some protection but you may need a dew band in heavier dew conditions.

Some folk use a hairdryer to eliminate the dew, just don't immediately try and clean it with a tissue/cloth or you may loose those lovely coatings on the optics. Once dry and at a stable temp if the optics need cleaning (THEY DO NOT MOST OF THE TIME! ) it is worth investing in som Baader Wonderflud and cloth to clean.

Cheers

[M4lcs67]

Yep. MAK's and SCT's are very suceptable to dewing up. I have one of each and can confirm that it is a problem. It is basically damage limitation. You will need to get a dewsheild at least, but if that has no effect then the only option would be to get a dew suppression system (heatertape and controller). With regards to bringing from one extreme temperature to another (hot to cold), just set it up outside and leave it to cool down (so the temperature inside the tube has equalized with the ambient temperature outside) before you start observing.

When bringing inside after observing the whole rig will be damp and covered in moisture. Just leave it in a corner (away from direct heat like a radiator) until it has warned back up to room temparature again. Make sure you keep the covers off the ota until you cannot see any more mist. Then put the covers back on. Also you correctly mention about not touching the glass. Leave well alone.