Pages

7/17/2015

The Fallacy of Light Shields to Bring Out More Detail of What I Observe from a Light Polluted Zone: What Does Help?


     I had a wonderful evening of observing yesterday and will post that up this weekend after I take the pictures of my sketches.  Today though, I want to address something that I think suburbia observers need to really think about. Often, and I did this, to improve their observing, amateurs build light shields to try and minimize the impact of stray light into their telescope and focuser/eyepiece. I did that a 2008 and 2009 and used them when observing in the backyard.  You can see the ones I built (this is one, I built over 12 of them):


     I know I read one of my 2009 blogs and found that I was saying that they improved my dark adaptation. Well, no, they didn't because in the backyard where I live, I am not going to get fully dark adapted. It is impossible because of the extremely large light dome I live under and next to.  I see that like last night when I look to the northwest and see that light dome creeping over the mountains now. What the light shields did do for me was to help keep stray light out of my eyes so that I could see what there was/is to see the best I can see it.  For example, I posted how the shields helped me to see the Milky Way one night. No. The Milky Way was there and is to be seen as faint as it is, but the shield let me keep that local stray light out of my eyes so I could perhaps maximize what I was seeing. The sky is the sky where you observe. Light pollution is light pollution and I can put up all the light panels I want, blacken my solid tube dob or put on a shroud, and put up light shields. That is NOT going to change the impact of light pollution in the sky and on the objects you see.  Just is not going to happen. It will help to lesson stray light that is coming in and to help you to see everything there is possible to see based on the sky conditions for that night.

     So there, I got that out.  I no longer use light shields when I am in the backyard. No one in the back area has lights on at night and we all are adjacent to a park so that helps.  I do have stray light though and yep, it can impact me.  So why not use the light shields? I am getting older now, still 50 years young but not 30, or 40 or even 45 years young.  I've gotten lazy I guess.  So what I do do is to take either a black bath towel I purchased for this purpose, and use it over my head while observing. It is the cheapest and most effective way I have found in the backyard to minimize stray light. Works wonderfully.  The other option I have is the Dark Skies Apparel Black Hood.  That can be purchased at this LINK and here is an example I grabbed off Google of someone showing how it works.



You can purchase the hood just as a hood, that is what I did or with a vest to hold your eyepieces and other items.  Both the hood here or a black towel will do the job, but the hood looks a lot cooler when you stand up and it is designed to fall over your head and eyepiece so your covered.  It's why I own one and use one.

     So if you are a backyard observer, and I think at some point we all are, limiting the impact from stray light helps to improve what you see, but it is no substitute for going to a dark site and observing if you want to see more detail.  Observing from the backyard in a light polluted area and minimizing the stray light will help your eye to see what there is to see, which often, is not much.  Want to build lights shields like these to help:






then go right ahead. They are excellent examples of home made, nicely price observatories.  Doing visual astronomy, they will help to block the stray light but it won't make you see something that isn't there. I know from experience that is the case.  A black towel or a Dark Skies Apparel (no affiliation with them for profit fyi) hood or hood and vest can be equally helpful.  The best bet though is to get out to a good old true dark site, and then see the change in details that occur.  Until then, the backyard can suffice.  Oh, if you live in the Salt Lake City area and want some of my old light shields, you can have all but 3 of them.  Contact me and make arrangements to pick them up. Keep observing the wonders of our universe, its a blast! Oh, I will mention though that if your imaging, then I think these setups would help to definitely keep the stray light out of your image and that is very important. 

No comments:

Post a Comment