Present gear: 16-inch f/4.5 Dobsonian 50mm straight through-finder Green laser pointer 26mm, 32mm, and 38mm 70 degree field EPs 4.7mm, 14mm and 18mm 82 degree field EPs 8mm, 17mm, 21mm 68 degree field EPs 2X 2" Barlow Tirion star atlas (white stars, black background) hand-laminated Megastar Editor & co-founder Las Vegas Astronomical Society Observer's Challenge To nudge or not to nudge, that is the question www.fredrayworth.com
Ken Fiscus- stargazing since 1980. Now observing from a green zone.
Z12 on custom mount, Atomic EQ platform, 100% flocked, OMI primary, Astrocrumb filter slide with O-III, NPB, & skyglow filters. Focuser & spider rotated 45 degrees. New springs & Bob's Knobs, Telrad & 9x50 straight finder 35 & 24 Pans, TV 13,7,5 T6s
Custom Orion XT10 with piggyback XT4.5 on Round Table EQ Platform
Quote:No hard rules when it's comes to filter use. 1. Get the object in the eyepiece.2. Try a filter for best view.3. Keep notes. My 16mm with a UHC filter slightly improved the Andromeda galaxy. I guess the extra field of view over the plossl and the filter's contrast function is why. No other galaxy appeared better. But I'm a cluster and nebula guy.
C-11 SCT, XT10i Dob, C-6 SCT, ETX125PE Mak-Cass, TV102, & AT66
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The heavens declare the glory of God; the skies proclaim the work of his hands." Psalms 19:1
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Quote:Quote:No hard rules when it's comes to filter use. 1. Get the object in the eyepiece.2. Try a filter for best view.3. Keep notes. My 16mm with a UHC filter slightly improved the Andromeda galaxy. I guess the extra field of view over the plossl and the filter's contrast function is why. No other galaxy appeared better. But I'm a cluster and nebula guy. There are four very important rules for nebula filter use:1. Get good and dark adapted (20 to 30 minutes in total darkness) and take steps to stay that way (local light shielding, observing hoods, etc.).2. Use averted vision extensively. Many of the details in nebulae which filters enhance are quite faint, so averted vision can really help here.3. Start low in power (recommended range: 3.5x per inch of aperture to 9x per inch of aperture, with somewhat better performance in the lower half of this range). You can use nebula filters at higher magnifications, but for the larger or more diffuse objects, lower powers tend to be somewhat more useful.4. Don't expect too much. Nebula filters can't make objects brighter, but they can help make them quite a bit easier to see. Clear skies to you.
Quote:Nice scope, and it is good that you have O-III because this one is used quite often, e.g. on planetary nebulae, supernova remnants, and HII regions in galaxies. Beyond that there are a handful of nebulae that are enhanced by an H-beta filter (California Nebula, the Horsehead, and a few of the more exotic pickings). Some use a narrowband filter than combines these two wavelengths and report that on certain nebulae it is better than either O-III or H-beta; I don't have such a filter. So you already have the most important of the two or three filters that you may want for deep sky. Enjoy! There is so much to see with no filters (galaxies and star clusters, and many nebulae too) or with just the O-III.
Quote:Some use a narrowband filter than combines these two wavelengths and report that on certain nebulae it is better than either O-III or H-beta; I don't have such a filter.
Quote:The degree of contrast increase depends primarily on the band pass, which controls how much the sky is darkened.
Quote:I've read that the UHC dims the sky by about 1.6 magnitudes (a factor of nearly 4.4) and the narrower O-III and H-beta dim the sky by about 2.6 magnitudes (a factor of nearly 11.) This may vary depending on the composition of the light contributing to sky glow.