How to remove dew?

EzyStyles (Eric) · #1 04-04-2006, 12:27 AM

Hi,

Was just wondering if I can remove dew by simply using a hair dryer or even a small heater? seems as the weather get colder in Melb condensation/dew plays a big roll.

Any advise would be appreciated. Thanks.

nightsky · #2 04-04-2006, 12:37 AM

Hi,a dew cap would help , I had a m8 with a DOB and he used to use a portable hair dryer but sometimes he had a problem with foging, but he still thought it helped.
BTW it was a 20" mirror

RAJAH235 · #3 04-04-2006, 02:06 AM

Ezy, try a 12 volt hair dryer. Works fine. Just be sure to use a large capacity battery n don't use it all night... also can build a tube extension..
HTH.

L.

acropolite (Phil) · #4 04-04-2006, 08:19 AM

Ditto what Laurie said. 12 Volt hairdryers can be had for under $20 from most marine suppliers.

nightsky · #5 04-04-2006, 08:23 AM

Quote:

Originally Posted by acropolite

Ditto what Laurie said. 12 Volt hairdryers can be had for under $20 from most marine suppliers.

marine suppliers!!! those fisher men, always have to have there hair looking good lol

rmcpb (Rob) · #6 04-04-2006, 08:37 AM

The dryer is a good idea but try all you can to stop, or at least delay, the problem in the first place. Tube extensions are the go in this department and never leave your scope pointing up if you are not using it, set it horizontal during rest periods.

Another really good preventative for newtonians is to fit a fan that blows the air out the front of the scope. Since fitting one on my scope I have had a LOT less dew problems.

Striker (Tony) · #7 04-04-2006, 11:20 AM

Best way to remove dew is to prevent it in the first place.

I have an orion dew heater and orion dew shield on the c11.....I have yet to ever have any dew on the optics.

sheeny (Al) · #8 04-04-2006, 06:02 PM

Yes I agree. Prevent it as much as possible. A tube extension or dew shield is a good passive measure.

Procedurally minimising time with the tube looking up is good as well, and it helps the tube extension / dew shield work.

The next priority I suggest should be a dew heater, but that may end up more expensive than a 12V hair drier, so depending on your budget you might choose to go with the hair drier first? Up to you. If the dew is really heavy the heater is a must! I have experienced dew that recurs in less than 10 mins after using the hair drier... hopefully it's not so bad where you are?

I have and use all the above dew solutions on my C8... I tried for a long time with just a dew shield, but up here... there's just no chance!

Al.

matt · #9 04-04-2006, 06:31 PM

Same here Al.

With the rate of temperature drop-off and the overnight lows here in Canberra, anything with a corrector plate without active heating is trouble waiting to happen.

I can imagine your environment would be easily the equal of here.

Just ordered the Kendrick Model VI standard dew controller and astrozap heater for my 9.25.

That should be a good start

acropolite (Phil) · #10 04-04-2006, 06:35 PM

Dew heaters are great on SCT's but I think Ezy has a Newt...

Striker (Tony) · #11 04-04-2006, 06:56 PM

Good point Phil.

But wouldn't a dew heater work as well on a newt as a SCT...all you need to do is increase the internal temperture a degree or 2.

anthony2302749 · #12 04-04-2006, 07:32 PM

With a newtonian the may concern is to keep dew from settling on the secondary mirror, therefore Ezy would need some method of warming the secondary so that it is just above dew point so as to prevent fogging. There are dew zappers design to do such a job.

sheeny (Al) · #13 05-04-2006, 01:27 PM

From memory when I had my Newt, I had issues with dew on the primary a reasonable number of times. Being at 1100m, temps get pretty low here, so dews are pretty frequent and often heavy.

Having said that, apart from installing some resistors on the secondary to warm it up, the hair drier would be the way to go.

I would bow to the advice of more experienced newt owner re: dew control on the primary. I didn't have any method to combat it when I had my newt. A dew heater may work around the outside of the mirror, or even on the back of the mirror, but I wonder about the potential for thermals in the tube???

Dew heaters can be a bit of necessary evil!

Al.

janoskiss (Steve H) · #14 05-04-2006, 02:30 PM

What is dewing up, Eric? Eyepieces, secondary, primary, finder? All of the above?

EzyStyles (Eric) · #15 06-04-2006, 11:37 PM

thanks for your replies so far guys. i think i stick to the hair dryer method. a cold air hair dryer might be better than hot air.

Hey Steve, my primary and eyepieces are dewing up.

janoskiss (Steve H) · #16 07-04-2006, 01:02 AM

Primary? Ouch! Hair dryer won't help there. Baffled fan behind mirror should though (and also with cooling) if you haven't got one yet. If you do, I have no idea. My 8" never dews up with the fan on (and only rarely with the fan off).