When you go from inside to outside to take a picture, there is a difference in temperature at the moment, and the telescope fogs up.  Now, if you want to continue shooting at this point, you need to take the time to clear the fog from the telescope, otherwise, you won’t be able to shoot.  If you don’t want to spend time cleaning your telescope’s lens of fog, you should take some precautions to prevent the telescope from fogging in the first place.  Let’s learn how to prevent the telescope from fogging up.  

1. Why do telescopes fog?  

The first is when the binoculars are carried from the outside to the inside, the telescope lenses fog due to temperature differences.  

The second is when you take cold binoculars and place them over your eyes, and the breath or moisture from your eyes or skin condenses into a fine mist on the lens, which also fogs up.  

The fog on the lens is nothing more than condensed water vapor.  This happens when optical devices are exposed to rapid extremes of temperature, more precisely from cold to warm.  

2. How to prevent the telescope from fogging up?  

How to prevent the telescope from fogging up?  There are several ways to avoid this.  The first is to put the binoculars through a slow cooling or heating process with little difference in temperature.  This may not be practical.  The second method is to apply a special gel or product to the lenses to prevent fogging.  The third way is to store the telescope in a dry place.  The telescope should be stored safely when not in use.  Desiccant is ideal for good storage and should be placed in an airtight container with binoculars.  Desiccant absorbs excess water in binoculars.  This eliminates the cause of fogging from the binoculars and prevents fungal growth.  

Fogging of telescope lenses, whether on the outside or the inside, is a common fact and can be avoided in some cases and not in others.  This isn’t something to worry about too much, but be careful to store your binoculars for long periods of time, especially in areas with large temperature differences between day and night or high humidity.  I recommend that you store them in a vacuum-sealed bag to avoid the above problems as much as possible.  

FAQ:

How do I stop condensation on my telescope mirror?

To prevent condensation, lock the cold outside around the primary with some kind of airtight covering before you bring it in. The cold outside air will be much drier than the inside air (warm air holds more moisture). When the mirror has warmed to the inside temps, you can remove the covering if you wish.

How do you bring a telescope to the cold?

put one on the controller of the telescope to keep the display from freezing up. Grab an old rug to put on the ground to insulate your feet while standing. Dew shields or lens warmers are a must for the telescope and don’t forget your camera lens too if you’re shooting piggyback.

Do reflective telescopes need dew shields?

Reflector telescopes do not require dew shields because the primary mirror is located at the bottom of the optical tube, and the tube acts as a natural dew shield.

Is humidity bad for telescopes?

Humidity has no direct effect on the views through a telescope.

Is it OK to store a telescope in a garage?

You might consider a good spot for your telescope to be in your garage or shed. Just make sure it is insulated against dampness and excessive heat forming. The same holds true for basements, closets, or other storage areas where you intend to store your instrument.