Thursday, January 27, 2005

First sight with filters

The First 8 minutes with the Filters, 24-Jan-99

This is the first night that there is at least some un-cloud-covered areas in the sky since the arrival of my new discounted Orion Ultrablock and an Antares #12 yellow color filter.

I rushed to my observing site since the Orion Nebula will be out of sight range after 21:00. Luckily, I could get 8 minutes of observing time with the Orion Ultrablock. Since I would like to test the filter with greatest chance of getting a look at the Orion Nebula, I have threaded on my filter immediately. Looking at the Nebula reveals
a fuzzy patch, by removing the filter, I noticed that the condition is not so good for tonight, since the fuzzy patch nearly disappear after the removal of the filter. It's not the case before. Therefore, I could see that the Ultrablock is quite effective even when the condition of the sky is not so good. Let me see if I've chance to test again later, in a darker sky. You know, the sky is bright in my observing site. I could read a book there, so imagine how poor it is.

Then, I begin to try out the yellow filter. Since there's no planets with my range, I choose the Sirius. The yellow (with the filter) star is pretty and chromatic aberration is not very noticeable after using the filter. However, when I move the focuser a bit, I could see the color of the star change! Now, I see how a color filter helps us to
get good focus.

Orion Nebula Again, 10-Feb-1999

Just found that I could see the Orion Nebula in my small viewing window. Without the filter, only a hint of fuzziness can be seen.

With the filter, I could see much more fuzziness. I would say the result is very good. However, for the heavy light pollution, the viewable size of the nebula becomes rather small and so the same effect of the filtered view can be obtained by using a higher

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