Instruments and Imaging: How to prevent condensation inside a closed system?

In summary: If so, purging the scope under the driest (read lowest humidity) conditions possible with nitrogen may help to remove the moisture.
  • #1
Astrid
6
0
Dewing of a mirror or object glass can be countered with various devices
and methods, but its occurrence inside a closed system is particularly
problematic. I have received the following enquiry (from an experienced
observer who has used several instruments over many years) concerning
dew on a corrector plate, and would be pleased to hear from anyone who
who has a remedy:

'Having recently obtained an 8-inch Meade SCT I have been having serious
problems with condensation, which persistently accumulates on the inside
of the corrector plate. I have fitted a dew shield and tried a heater,
but these have been only partially successful in limiting and/or
delaying the inevitable.'
 
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  • #2
Have you tried flowing dry nitrogen over the affected area?
 
  • #3
The INSIDE of the corrector plate? Wow. I have a Schmidt-Newtonian and I use a hand held blow dryer, like the ones women dry their hair with, as a final resort if things get bad. It works pretty well and can even clear the inside of the corrector plate in a minute or two. It just sucks because sometimes you have to apply it every 15 minutes or so depending on how humid it is.
 
  • #4
Your friend needs a http://www.lymax.com/sct/. Run it inside the house where it is dry and warm to dry out the interior of the SCT.
 
  • #5
Astrid said:
...
'Having recently obtained an 8-inch Meade SCT I have been having serious
problems with condensation, which persistently accumulates on the inside
of the corrector plate. I have fitted a dew shield and tried a heater,
but these have been only partially successful in limiting and/or
delaying the inevitable.'

Dew shield/heater units are for condensation on the outside of the corrector plate...
something all us SCT owners suffer from, unless you live at really high altitude ;)

As hinted at by others... you really need to purge the inside of the scope OTA under the driest (read lowest humidity) conditions possible and consider filling the OTA with nitrogen to purge the damp air

this leads to the question tho ... how did moisture get in there in the first place ?
Have you had the OTA apart for main mirror cleaning etc ?

Dave
 

1. What causes condensation inside a closed system?

Condensation inside a closed system is caused by the presence of moisture in the air. When the temperature inside the system drops below the dew point, the moisture in the air condenses and forms droplets on the surface of the instrument or imaging device.

2. How can I prevent condensation from forming on my instruments or imaging devices?

To prevent condensation, you can use a desiccant, such as silica gel, inside the closed system to absorb excess moisture. You can also insulate the system to maintain a consistent temperature and reduce the chance of the temperature dropping below the dew point.

3. Can I use anti-fog coatings to prevent condensation?

Yes, anti-fog coatings can be applied to the surface of the instrument or imaging device to prevent condensation. These coatings work by reducing the surface tension of the water droplets, causing them to spread out and form a thin, transparent layer instead of large droplets.

4. Are there any other methods to prevent condensation?

In addition to using desiccants and anti-fog coatings, you can also use a heating element or a dehumidifier to control the temperature and humidity inside the closed system. Proper ventilation and air flow can also help reduce the moisture levels and prevent condensation from forming.

5. What are the consequences of condensation inside a closed system?

Condensation can cause damage to sensitive instruments and imaging devices, leading to malfunctions and inaccuracies in readings. It can also create a barrier to clear visibility, obstructing the user's view and hindering the performance of the device. Additionally, condensation can promote the growth of mold and bacteria, which can be harmful to both the equipment and the user.

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