TLDR: Dust and Dew.
- How worried should I be about dust on a nebula filter, or dew stains on my objective lenses?
- Are the black spots in my unsealed eyepieces really mold? Should I avoid buying such unsealed eyepieces in the future, or how can I most effectively prevent mold from forming in the first place?
- Does everyone really wrap their telescopes and gear in big plastic bags when moving from indoors to outdoors in areas with humidity? I often drive to and from observation locations. This would be a real blow to my grab-and-go process.
Three unrelated events have me wondering (and worrying) about the proper care of telescope optics.
The first is my purchase of a used 2" Lumicon Oiii filter from CN classifieds for $155. The seller disclosed to me that it had some dust spots on it, but upon inspection there were more than I expected. I took the rubber rocket bulb air blaster that I use for my photo gear to it, but most of the dust persists.
Overall the filter and its coatings appear to be in great shape, but I am wondering how dust spots that late in the optics train will impact final images. I know that when I have spots on the diagonal those often jump out when put against bright targets like the moon. Are nebula filters more forgiving?
Second, while observing the full moon last night I noticed several dark spots in two of my cheaper, non-sealed and non purged eyepieces, the Orion 7-21mm zoom and a Paradigm 8mm. I tried blasting them with air also, in case it was just dust. But to no avail.
I am concerned that it may have been caused when I got ambushed by a wave of evening dew a week or so ago. I took great care to dry out my OTA, binoculars, and my eyepieces before putting them away. Is it possible that these less-expensive, non sealed and purged eyepieces developed internal moisture and mold from the fog event? By comparison, my Explore Scientific 82 eyepieces look perfect.
Third, as a result of the dew assault, the objective lenses of my telescopes and binos did develop some dew stains. I know many folks on here advocate against ever touching objectives, but I was surprised to see just how many folks in this thread (virtually all) advocated attacking such spots with microfiber cloths, distilled water, and perhaps a specialty solution that is ammonia-free. https://www.cloudyni...f-how-to-clean/