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do i realy need filters?

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#1 astroman100082

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Posted 15 July 2013 - 04:13 PM

Hey everyone,
I have the Celestron cpc 1100, and I live in the desert, so light pollution is realy not my problem. I can go just outside my house, or drive for a few miles if I want a realy dark site.
I want to see DSO's with all their glory, and I wonder if I'll need any filters to do so. I already have 0III filter...

Thanks :jump:

#2 Feidb

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Posted 15 July 2013 - 04:21 PM

If you already have an O-III, you should be set for a lot of nebulae. Most filters won't help on galaxies so forget that. If you want to catch certain dark nebulae like the horsehead, an H-beta would help tremendously. For some objects, a UHC might help regardless of light pollution.

All in all, if you have access to a really dark site, right now, you should do just fine with the O-III for a lot of nebulae. However, it won't do you any good on galaxies, or most of them. Then again, if you already had a few more filters, you have the option of experimenting on the brighter galaxies and maybe eking out something. You can try that O-III on some and see what happens.

Keep in mind that the O-III, while a wonderful tool, is not the perfect filter for ALL nebulae and will actually worsen the view of some.

A long and complicated way to tell you no, you don't HAVE to have any more filters, but a variety doesn't hurt either. They aren't just for light pollution.

#3 astroman100082

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Posted 15 July 2013 - 04:43 PM

ok thanks for the reply Feidb!
One more thing, can you recommend me on some good bright DSO's that I can watch these nights, and maybe on some SDO's that I can enhance with OIII...
Thank you very much

#4 AstroTatDad

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Posted 15 July 2013 - 05:43 PM

There is a lot of good objects to check out right now, I like looking at the southern part of the milkyway.
Check out this link on what filters will be best to use. http://www.prairieas...ter-performa... By David Knisely.

#5 kfiscus

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Posted 15 July 2013 - 06:04 PM

The following is a partial list of DSOs that I've observed lately, appreciating the vast improvements made with either my Lumicon O-III or DGM NPB filter.

Veil Nebula (all parts)
Crescent Nebula
Omega/Swan
Lagoon
Trifid
Eagle
Multiple planetary nebulae (M-27,57, 6543, etc.)

#6 Kraus

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Posted 18 July 2013 - 11:46 AM


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.

#7 David Knisely

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Posted 18 July 2013 - 12:51 PM

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.

#8 blb

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Posted 18 July 2013 - 02:14 PM

Do I realy need filters? NO! you do not need to have filters but they can and will show you much more on planetary nebula and/or emission nebula. ;)

#9 acochran

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Posted 18 July 2013 - 03:37 PM

Don't really NEED them, but...
I only own DGM NPB filter, because I'm currently low on money. Sure glad I have at least the one though. Especially now with Sagittarius and Cygnus in the sky.
Andy

#10 Kraus

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Posted 18 July 2013 - 04:44 PM


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.


OK. I'll go with that. I often employ number 1 and 2. Number 1 goes without saying. We all adore the dark. So is our hobby a dark 'art'?

#11 azure1961p

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Posted 18 July 2013 - 09:40 PM

In planetary observation of well, the planets a lot of folks are either diehard filter users (like me) or just as soon have the view unattenuated. Its a take it or leave it thing.

With planetary nebula, emission nebula and such there is no doubt it'll help. There's very little descension in the ranks on that. Some nebula will be utterly invisible without them.

Because u have an OIII do yourself a favor and get an HBeta. This is an exquisite filter. Though the list might not be as long as OIII fare there's still a lot to choose from . You could get a UHC which is a little like a liberal OIII or a diluted Hbeta, but the Hbeta into itself will expand your horizons the way the UHC simply can't. Its a great tool for some exotic stuff.

Pete

#12 kfiscus

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Posted 19 July 2013 - 09:32 AM

Need? No.
Want? Yes.

#13 IVM

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Posted 19 July 2013 - 10:20 AM

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.

#14 David Knisely

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Posted 19 July 2013 - 12:45 PM

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.


Well, it might be a bit more than just a "handful"....

. . . . USEFUL TARGETS FOR THE H-BETA FILTER . . . .

While the H-Beta is probably one of the less-used nebula filters, the commonly expressed idea that it works only on a handful of objects is not necessarily true. Here is a list of some of the more prominent objects that the H-Beta may be at least somewhat useful on. Some may require larger apertures, but a few have been seen from a dark sky site by just holding the filter up to the unaided eye and looking at the sky. Some of these will also be helped by a narrow-band filter like the Lumicon UHC.

1. IC 434 (HORSEHEAD NEBULA)
2. NGC 1499 (CALIFORNIA NEBULA, naked eye and RFT)
3. M43 (part of the Great Orion Nebula)
4. IC 5146 (COCOON NEBULA in Cygnus)
5. M20 (TRIFID NEBULA, main section)
6. NGC 2327 (diffuse nebula in Monoceros)
7. IC 405 (the FLAMING STAR NEBULA in Auriga)
8. IC 417 (diffuse Nebula in Auriga)
9. IC 1283 (diffuse Nebula in Sagittarius)
10. IC 1318 GAMMA CYGNI NEBULA (diffuse nebula in Cygnus)
11. IC 2177: (Diffuse Nebula, Monoceros)
12. IC 5076 (diffuse nebula, Cygnus)
13. PK64+5.1 "CAMPBELL'S HYDROGEN STAR" Cygnus (PNG 64.7+5.0)
14. Sh2-157a (small round nebula inside larger Sh2-157, Cassiopeia)
15. Sh2-235 (diffuse nebula in Auriga).
16. Sh2-276 "BARNARD'S LOOP" (diffuse nebula in Orion, naked eye)
17. IC 2162 (diffuse nebula in northern Orion)
18 Sh2-254 (diffuse nebula in northern Orion near IC 2162)
19. Sh2-256-7 (diffuse nebula in northern Orion near IC 2162)
20. vdB93 (Gum-1) (diffuse nebula in Monoceros near IC 2177)
21. Lambda Orionis nebular complex (very large, naked-eye)

In addition, a number of the brighter nebulae like NGC 7000 or M42 will respond to H-Beta use for revealing certain specific detail, although other filters may provide a somewhat better view overall.

Clear skies to you.

#15 IVM

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Posted 20 July 2013 - 10:42 AM

Thanks, David! A very useful list.

#16 Robert Cook

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Posted 25 July 2013 - 10:50 AM

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.


Nebulae that emit in all of these wavelengths will be brighter and generally show more at once when using a narrowband/UHC filter, although OIII and H-beta filters are still potentially useful for isolating certain features within such objects. Going by the numbers, the most broadly useful nebula filter overall is the narrowband/UHC, in my opinion, so it's probably the one to get if you'll only ever have one. On the other hand, some would argue that the OIII provides better contrast and detail on many objects that emit in these wavelengths, and I wouldn't dispute that.

#17 GlennLeDrew

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Posted 25 July 2013 - 01:36 PM

The degree of contrast increase depends primarily on the band pass, which controls how much the sky is darkened. 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.

#18 Robert Cook

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Posted 26 July 2013 - 06:45 PM

The degree of contrast increase depends primarily on the band pass, which controls how much the sky is darkened.


Well, there are two sides to contrast, namely the sky and the nebulae themselves, and in some cases a narrower bandpass darkens both.

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.


It can vary greatly depending on the specific filters (not just the basic type, but the brand and such) being compared, as well, and the overall effect varies widely between different nebulae. Many nebulae emit significantly in both the OIII and H-beta lines (and H-alpha, although our eyes are far less sensitive to it), and will appear brighter and perhaps even more contrasty overall if there isn't much light pollution in the region of the visible spectrum between the OIII and H-beta lines. In many cases, a UHC filter will let you see more of the nebula. On the other hand, filtering out the H-beta line can reveal some additional structure in OIII that had been obscured by H-beta, and vice versa.

All three narrowband nebula filter types are useful for visual observing. The UHC is sort of the jack of all trades and master of many, the OIII is the jack of many trades and the master of many others (different set from that of the UHC), and the H-beta is the master of relatively few but significant nebulae (also gives a different and unique view of a number of others).

#19 GlennLeDrew

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Posted 27 July 2013 - 04:54 AM

To be strictly correct, the UHC is a master of two trades, and the O-III and H-beta each are masters of but one trade. :grin:






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