Help Needed In Finding Planetary Nebulas.

[renormalised (Carl)]

Originally Posted by jjjnettie

LOL @ Carl
You're pushing her over to the dark side now.
But he's right Suzie. If you want to see faint fuzzies live on your telly or computer sceen, the Gstar-Ex is the way to go. No more squinting up to an eyepiece.
Here's a link to an article about beginning Astrophotography using a Gstar.
http://www.ioptron.com/images/up/ATT...on_Article.pdf

How appropriate, I have the "Imperial March" from Star Wars playing on iTunes

Suzy...the power of looking through an eyepiece pales into insignificance, when compared to the Dark Side of the Force (***heavy scratchy breathing***)

[erick (Eric)]

Suzy, if you are chasing Planetary Nebulae, you should get an OIII filter to help. Bintel sell a GSO 1.25" OIII for $89. You may find it cheaper or pick one up in the classifieds. Slip it in and hold it between your eye and the eyepiece when you think you have the PN in the field. The stars will dim, but the PN will not dim as much and is contrasted against the stars.

Yes, over the next month or two, the Ring Neb is the one to go for. Easy to locate. The Blue Planetary eluded me for quite a while. It is a difficult star hop from Delta Crucis, but once you reach it, it is very clear. You'd think you are looking at Uranus or Neptune!

Here is an unexpected one. Go looking for Messier 46 (NGC 2437) open star cluster in Puppis and you get a surprise (it is NGC 2438!)

[jjjnettie (Jeanette)]

Yes!! M46 is a real treat. It's a beautiful open cluster, but look a little closer.

[mental4astro (Alexander)]

Suzy- strength lies within yourself. Those who are weak relie on the dark side of give them false eyes. Make the force your friend. It will reveal its true beauty if you listen to it. (*** exit left of stage- crunching gravel heard as Imperial Forces approach***)

[renormalised (Carl)]

Originally Posted by mental4astro

Suzy- strength lies within yourself. Those who are weak relie on the dark side of give them false eyes. Make the force your friend. It will reveal its true beauty if you listen to it. (*** exit left of stage- crunching gravel heard as Imperial Forces approach***)

Fluke Skytripper, you' will not elude me next time!!!

[Suzy]

Alexander and Carl.. you'll are so funny!

[renormalised (Carl)]

He does not know the true power of the Dark Side

Seriously, it's amazing to be able to see stars you'd have no chance of finding normally through an eyepiece just pop up into view...and with the colour version of the camera, they've reported seeing colour in many of the brighter DSO's, live onscreen.

[ausastronomer (John Bambury)]

Originally Posted by sjastro

The UHC will help but it is nowhere near as effective as an OIII filter.
Steven

Hi Suzy,

With only 6" of aperture the UHC filter is a better choice than the OIII filter IMO. The OIII is a much harsher filter than the UHC and will provide an overall significantly dimmer view than the UHC filter. This applies even moreso if your skies are less than pristine, in terms of light pollution. In addition, the UHC is more flexible than the OIII and will work on a wider range of targets. True the OIII will improve "some" planetary nebula more than the UHC, but overall the UHC will provide a noticeable benefit over the OIII on more targets and a wider range of targets.

The planetary nebula that have been recommended to you are all ideal targets for a 6" telescope.

NGC 3918 (Blue Planetary)
NGC 3242 (Ghost of Jupiter)
NGC 3132 (Eight Burst)

These are all easily visible in a 6" scope from 1/2 decent skies without any filter. You just gotta point it in the right place and the finder charts provided to you will help enormously.

Cheers,
John B

[Brian W (Brian)]

Hi Suzy, Later on don't forget M-57.
Brian

[Liz]

Hey Suzy ... many PNs to have a search for, very exciting!! Look forward to you finding your first ... whether it be for the dark or the light.
Great to hear John's thought that the UHC was better for you, cos thats what you have bought.

[sjastro]

With only 6" of aperture the UHC filter is a better choice than the OIII filter IMO.

Filters are selected on eyepiece FL not aperture. The Lumicon UHC filter in light polluted skies is designed for an exit pupil range of 1-4mm, the OIII 2-5mm.
So for example, using a f/6 scope, the recommended eyepiece FL range for the UHC filter is 6-24mm, the OIII filter is 12-30mm.

The OIII is a much harsher filter than the UHC and will provide an overall significantly dimmer view than the UHC filter. This applies even moreso if your skies are less than pristine, in terms of light pollution.

For light polluted skies the opposite is true. The bandpass of the UHC filter is 22-26nm, the OIII is 10-12nm. The OIII will reject more light pollution and significantly improve contrast in light polluted skies for planetaries and emission nebulae. The apparent gains of using a wider bandpass UHC are lost in the reduced contrast of light polluted skies when compared to the OIII filter.

Regards

Steven

[ausastronomer (John Bambury)]

Originally Posted by sjastro

For light polluted skies the opposite is true. The bandpass of the UHC filter is 22-26nm, the OIII is 10-12nm. The OIII will reject more light pollution and significantly improve contrast in light polluted skies for planetaries and emission nebulae. The apparent gains of using a wider bandpass UHC are lost in the reduced contrast of light polluted skies when compared to the OIII filter.

Regards

Steven

Steven,

It's obvious you have done some extensive internet research on these filters and the numbers would appear impressive and authoritative.

I can't match the informativeness of those numbers because all of my filter research has been done with the filter on the end of an eyepiece, stuck in a telescope, out under the stars. I can't find those numbers out in the bush in the dark. I have been doing these same "low tech" filter evaluations for a lot of years and they work for me.

Originally Posted by sjastro

Filters are selected on eyepiece FL not aperture. The Lumicon UHC filter in light polluted skies is designed for an exit pupil range of 1-4mm, the OIII 2-5mm.
So for example, using a f/6 scope, the recommended eyepiece FL range for the UHC filter is 6-24mm, the OIII filter is 12-30mm.

I don't dispute the fact that certain filters are designed to work at certain f-ratios and with certain exit pupils. This has nothing to do with my statement that an OIII filter works better with larger aperture telescopes, than it does with smaller aperture telescopes.

To quote respected US author Phil Harrington in edition 3 of "Star Ware" Para 2 Page 221, "Owners of medium and large aperture telescopes should also give consideration to an OIII filter"

Copied straight from the website of the Binocular and Telescope shop in Sydney:-

http://www.bintel.com.au/Filters.html

Click "Astronomik Bandpass Filters" then click "OIII filter"

Astronomik Profi OIII
Product information:

The Astronomik OIII filter is designed for visual observation of gas nebulas and planetary nebulas. Due to the extreme small band pass of the two OIII- lines, the filter will produce a relevant increase of contrast even under best observing conditions. At faint super nova remnants and faint planetary nebulas the Astronomik OIII filter often makes the gain, that decides if the object can be seen or not.

The best focal ratio for the use of this filter is 1:4.5 to 1:6. The field of application is from 1:3,75 up to 1:15. Loss of transmission and colour displacements, that appear at other filters, emerge with the Astronomik filters only at extreme light intensive focal ratio of 1:3 and bigger. So you can see widespread objects in the whole field of view and not only in the middle.

The OIII filter is to be used from a aperture of more than 6" (15cm) on. At smaller instruments there is not enough light available for a sensible use. Many experienced Deep- Sky- observers rather use the OIII filter at instruments with more than 10" (25cm) despite the smaller field of application than the more versatile UHC filter.

Directly from the Oceanside Photo and Telescope Website (OPTCORP) in the USA

http://www.optcorp.com/product.aspx?...-826-1622-1893

Astronomik OIII Filter for Visual Use - 2" Mounted

This Astronomik OIII Filter is made for visual observing of gas and planetary nebulae.

This model is mounted in a 2" metal cell.

With a FWHM of ca. 15nm, the Astronomik OIII Filter transmits at nearly 100% in the OIII line.

On larger telescopes (10" & over), this may very well be the filter of choice for deep-sky observing.

Astronomik OIII Filters are best on telescopes of at least 6" of aperture.

Astronomik 2" OIII Filter for Visual Use
From the start, the Astronomik OIII filter has been very specifically designed for the visual observation of gaseous and planetary nebulae. The extremely narrow pass band of the two OIII lines brings a substantial contrast gain to these lines even under best observation conditions. On faint super nova remnants and faint planetary nebulae the Astronomik OIII filter will often make the difference as to whether the object can be seen or not!

The optimal aperture ratio for the use of the filter is 1:3 to 1:15 with apertures of more than 6" (150mm). Transmission losses and chromatic distortions, which arise with other filters, occur with Astronomik OIII filters only when extremely bright aperture ratios of 1:3 and more come into play. The Astronomik OIII filters thus can expand the view of dispersed objects, generally speaking, to the whole visual field of view of the eyepiece and are not limited to only the center of the eyepiece.

The information on both the Bintel and Optcorp websites looks like it's a direct spiel from the filter manufacturer (Astronomiks in Germany).

Just wondering why, "if you're right and I'm wrong", the filter manufacturer agrees with me and further, why the largest astronomical dealer in Australia and one of the largest in the USA, post incorrect information on their website?

Cheers,
John B

[sjastro]

I can't match the informativeness of those numbers because all of my filter research has been done with the filter on the end of an eyepiece, stuck in a telescope, out under the stars. I can't find those numbers out in the bush in the dark. I have been doing these same "low tech" filter evaluations for a lot of years and they work for me.

The key point here is observing planetaries in light polluted skies.
There is absolutely no doubt that an OIII filter will outperform a UHC filter under these conditions.
Do your filter evaluations include light polluted skies? If not you cannot assume that relative filter performance is equivalent under different sky conditions.

To quote respected US author Phil Harrington in edition 3 of "Star Ware" Para 2 Page 221, "Owners of medium and large aperture telescopes should also give consideration to an OIII filter"

Copied straight from the website of the Binocular and Telescope shop in Sydney:-

http://www.bintel.com.au/Filters.html

Click "Astronomik Bandpass Filters" then click "OIII filter"

Astronomik Profi OIII
Product information:

The Astronomik OIII filter is designed for visual observation of gas nebulas and planetary nebulas. Due to the extreme small band pass of the two OIII- lines, the filter will produce a relevant increase of contrast even under best observing conditions. At faint super nova remnants and faint planetary nebulas the Astronomik OIII filter often makes the gain, that decides if the object can be seen or not.

The best focal ratio for the use of this filter is 1:4.5 to 1:6. The field of application is from 1:3,75 up to 1:15. Loss of transmission and colour displacements, that appear at other filters, emerge with the Astronomik filters only at extreme light intensive focal ratio of 1:3 and bigger. So you can see widespread objects in the whole field of view and not only in the middle.

The OIII filter is to be used from a aperture of more than 6" (15cm) on. At smaller instruments there is not enough light available for a sensible use. Many experienced Deep- Sky- observers rather use the OIII filter at instruments with more than 10" (25cm) despite the smaller field of application than the more versatile UHC filter.

Directly from the Oceanside Photo and Telescope Website (OPTCORP) in the USA

http://www.optcorp.com/product.aspx?...-826-1622-1893

Astronomik OIII Filter for Visual Use - 2" Mounted

This Astronomik OIII Filter is made for visual observing of gas and planetary nebulae.

This model is mounted in a 2" metal cell.

With a FWHM of ca. 15nm, the Astronomik OIII Filter transmits at nearly 100% in the OIII line.

On larger telescopes (10" & over), this may very well be the filter of choice for deep-sky observing.

Astronomik OIII Filters are best on telescopes of at least 6" of aperture.

Astronomik 2" OIII Filter for Visual Use
From the start, the Astronomik OIII filter has been very specifically designed for the visual observation of gaseous and planetary nebulae. The extremely narrow pass band of the two OIII lines brings a substantial contrast gain to these lines even under best observation conditions. On faint super nova remnants and faint planetary nebulae the Astronomik OIII filter will often make the difference as to whether the object can be seen or not!

The optimal aperture ratio for the use of the filter is 1:3 to 1:15 with apertures of more than 6" (150mm). Transmission losses and chromatic distortions, which arise with other filters, occur with Astronomik OIII filters only when extremely bright aperture ratios of 1:3 and more come into play. The Astronomik OIII filters thus can expand the view of dispersed objects, generally speaking, to the whole visual field of view of the eyepiece and are not limited to only the center of the eyepiece.

The information on both the Bintel and Optcorp websites looks like it's a direct spiel from the filter manufacturer (Astronomiks in Germany).

Just wondering why, "if you're right and I'm wrong", the filter manufacturer agrees with me and further, why the largest astronomical dealer in Australia and one of the largest in the USA, post incorrect information on their website?

The proof of the pudding is in the eating and my own experiences support the Lumicon site that exit pupil diameter is more important than aperture.

I have used a C5 SCT (5 inch) and a OIII filter. The objects are enhanced even though the background is dark. The primary role of aperture is to define the field in which the object resides.
For example if I wanted to observe the planetary NGC 2438 in the cluster M46 then aperture will clearly play a role in defining the field. If I was only interested in the planetary then aperture is less important.

With the same scope the Helix nebula observed in surburban Melbourne under magnitude 4.5 skies with an OIII filter is more conspicuous than without a filter under magnitude 6.0 skies (my current site).

People should not be discouraged from using OIII filters on small telescopes.

Regards

Steven

[Suzy]

John & Steve I thank you for your input regarding filters, though I do remain a bit confused. Whilst this thread was going, I had actually bought a UHC filter from doing previous research on it prior. Though not sure how it will go with my 6" dob. It arrived today, and when (if) the weather ever clears, I'll give it a run and see how it goes.
I did come across this article a few days ago, it's interesting reading on filters. It's written by David Knisley. Though the review only mentions the studies were done on apertures of 8" and up (so I don't know where I stand), but it makes note of exit pupil. It also lists which nebulas perform best for each filter. You guys will make more sense out of this article than I will as you'll are more experienced in this field.
http://pages.sbcglobal.net/raycash/filters.htm

[astroron (Ron)]

Originally Posted by Suzy

John & Steve I thank you for your input regarding filters, though I do remain a bit confused. Whilst this thread was going, I had actually bought a UHC filter from doing previous research on it prior. Though not sure how it will go with my 6" dob. It arrived today, and when (if) the weather ever clears, I'll give it a run and see how it goes.
I did come across this article a few days ago, it's interesting reading on filters. It's written by David Knisley. Though the review only mentions the studies were done on apertures of 8" and up (so I don't know where I stand), but it makes note of exit pupil. It also lists which nebulas perform best for each filter. You guys will make more sense out of this article than I will as you'll are more experienced in this field.
http://pages.sbcglobal.net/raycash/filters.htm

Suzy, When the weather clears up you will be able to give us your opinion
Cheers

[astroron (Ron)]

Originally Posted by renormalised

How appropriate, I have the "Imperial March" from Star Wars playing on iTunes

Suzy...the power of looking through an eyepiece pales into insignificance, when compared to the Dark Side of the Force (***heavy scratchy breathing***)

Suzy, if you want to look at pretty pictures, download them from ICEINSPACE Or Hubble, or other fancy telescopes

[sjastro]

Originally Posted by Suzy

John & Steve I thank you for your input regarding filters, though I do remain a bit confused. Whilst this thread was going, I had actually bought a UHC filter from doing previous research on it prior. Though not sure how it will go with my 6" dob. It arrived today, and when (if) the weather ever clears, I'll give it a run and see how it goes.
I did come across this article a few days ago, it's interesting reading on filters. It's written by David Knisley. Though the review only mentions the studies were done on apertures of 8" and up (so I don't know where I stand), but it makes note of exit pupil. It also lists which nebulas perform best for each filter. You guys will make more sense out of this article than I will as you'll are more experienced in this field.
http://pages.sbcglobal.net/raycash/filters.htm

Hello Suzy,

A UHC filter is better than nothing. At a dark site a UHC would be the preferred filter, at a light polluted site an OIII filter is the way to go due to increased contrast.

Ultimately it depends on where you observe. Can you see the SMC from your site?

Regards

Steven

[Suzy]

Originally Posted by sjastro

Hello Suzy,

A UHC filter is better than nothing. At a dark site a UHC would be the preferred filter, at a light polluted site an OIII filter is the way to go due to increased contrast.

Ultimately it depends on where you observe. Can you see the SMC from your site?

Regards

Steven

No Steven, Can't see the SMC. I can see the Tarrantula Neb, but not the LMC that it resides in. I have given up trying to find galaxies from my back yard. Each time i get packed up ready to go to a dark site, the weather changes drastically.

[Suzy]

Originally Posted by astroron

Suzy, if you want to look at pretty pictures, download them from ICEINSPACE Or Hubble, or other fancy telescopes

They keep trying to pull me over to the dark side Ron... they nearly had me again, and I had to stay strong! I have to keep repeating to myself at least 100 times a day, "I am a visual observer!" I like what Alexander is doing with sketching, think I might like to have a go sometime. Though he has an upper hand on some serious aperture

[marki]

Large aperture counts for little in light polluted cities, what do you get? A better view of the street lights. A small scope with a camera will always reveal more celestial delights in the city than a large scope using the mark I eyeball. Unlike the others I don't think using a camera is cheating nor do I accept the "darkside" label. If anything you would be moving to the bright side i.e. you can actually see something .

Mark