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Need advice in choosing LP filter

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#1 0R10N5

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Posted 21 February 2019 - 12:39 AM

Hi friends, sorry if i am posting my topic in wrong section.

 

Two weeks back i purchased SW EQ6 PRO mount and ES ED100mm APO refractor. I want to use it for visual as well as for AP. I have Canon 1300D DSLR.

My city is full of light pollution and sky looks orange almost all the time. Due to this reason i am looking for light pollution filter for visual as well as for AP use. Yesterday while searching on amazon i found the following LP filter :

 

1. Orion 5657 2-Inch UltraBlock Narrowband Eyepiece Filter

2. Celestron 93624 Narrowband Oxygen III 2 Filter

 

As i have no idea which one is best so i need your advice in choosing LP filter. You all are expertise in this field, your help is much appreciated. smile.gif


Edited by 0R10N5, 21 February 2019 - 12:41 AM.


#2 Jond105

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Posted 21 February 2019 - 12:53 AM

If I may ask, how light polluted your skies are. I think for AP you may want one, but with such a nice scope for visual, it would be bad to add miscoloring to your targets. I have the Ultrablock I never use it anymore though. It does dim the view, and in all honesty turns everything blue. I feel you actually lose more than you gain. I live in a B9/8 zone in Detroit, so my skies are bright. The only thing I tend to use it on is Orion, other than that I don't. I can't comment on AP since I don't do AP, and this is just my opinion on LP in the city.

#3 sg6

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Posted 21 February 2019 - 02:57 AM

Choosing an LP filters are becoming a problem.

Traditional LP was from Sodium lamps and they were just 2 wavelengths fairly close to each other and as such were equally easy to cut those two out and have minimal effect.

 

The problem now is that LP is not just the Sodium, there are several others as well - Halogen, Mercury and now LED. And therein lies the real problem - you cannot with real success block everything.

 

If as you describe the sky is "orange" then a classic LP filter may help as what you describe implies a fair degree of sodium lamps. So how orange?

 

There are filters that basically pass up at the OIII+Hb end, then block everything, then pass again at the Ha wavelength. They in effect just wipe out the whole area where LP may/does exist.

 

I am never sure how I would describe them but "Nebula filter" seems fairly common. They pass the OIII, Hb and Ha that assorted nebula emit and then block the rest. Really you need to have available the filter characteristics and understand what they mean.

 

There is a "triband" filter out that reads to pass Red+Green+Blue in narrow portions and so blocks the general LP. They are likely not really for visual and they are costly.

 

Any filter you put in will alter the color balance, there is no real magic filter to remove LP alone and still leave the image "natural".

 

If the description is right (orange) then first have a look and see around and if the cause is numerous old Sodium lamps, and if they are present/dominent then consider a classic LP filter for sodium. As one will block that part of the spectrum. Wavelengths from other sources will still be apparent but the hope is the main problem gets removed so improving thing. It is also likely an inexpensive option to try.

 

For AP (mono) criteria are different and ask about that elsewhere.


Edited by sg6, 21 February 2019 - 02:58 AM.


#4 0R10N5

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Posted 21 February 2019 - 03:46 AM

@sg6 and @Jond105

 

 

If as you describe the sky is "orange" then a classic LP filter may help as what you describe implies a fair degree of sodium lamps. So how orange?

 

This is how sky looks like, i have attached a pic, very similar to this pic. I dont know what type of light is that but when it glows 1st time its white and within a minutes it changes color to orange. If this is confirmed as sodium light then i will get sodium filter.

 

Presently i will not use mono camera. I will use my DSLR.

Attached Thumbnails

  • picture1_8.jpg

Edited by 0R10N5, 21 February 2019 - 03:51 AM.


#5 Jond105

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Posted 21 February 2019 - 04:02 AM

From the picture you have a mixture of it all in there. My sky is a pinkish orange depending on atmospheric conditions and cloud cover. We have mixtures of sodium in outside of downtown and LED downtown. Visually you may just want to go with another type like an OIII. Just for any nights you get out of town, and when in town possibly use nothing visually to not dim down and change the color of viewing. Just my thoughts on it.

Hopefully for you, someone with AP knowledge can help out as they start waking up and seeing this thread.
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#6 Starman1

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Posted 21 February 2019 - 11:04 PM

Hi friends, sorry if i am posting my topic in wrong section.

 

Two weeks back i purchased SW EQ6 PRO mount and ES ED100mm APO refractor. I want to use it for visual as well as for AP. I have Canon 1300D DSLR.

My city is full of light pollution and sky looks orange almost all the time. Due to this reason i am looking for light pollution filter for visual as well as for AP use. Yesterday while searching on amazon i found the following LP filter :

 

1. Orion 5657 2-Inch UltraBlock Narrowband Eyepiece Filter

2. Celestron 93624 Narrowband Oxygen III 2 Filter

 

As i have no idea which one is best so i need your advice in choosing LP filter. You all are expertise in this field, your help is much appreciated. smile.gif

For visual and AP, a narrowband filter that transmits the H-ß line and both O-III lines in the spectrum will work.

These go by names like:

TeleVue BandMate II Nebustar

Lumicon UHC

Astronomik UHC*

DGM NPB*

Orion Ultrablock

Thousand Oaks LP-2

Since you'll use it for imaging as well as visual, you want the filter to pass red wavelengths.  I've starred the ones that do.

 

These filters work on emission nebulae like Hydrogen gas clouds, planetary nebulae, supernova remnants, and Wolf-Rayet excitation nebulae.

They do not work on other nebulae, like reflection nebulae or dark nebulae, or on galaxies, star clusters, etc.

 

Broader filters, called CLS filters or Broadband filters, or LPR filters, simply won't work for you in the severe light pollution you have.

The O-III filter you mention is a photographic filter and is too narrow for most visual use.  You won't even see an image in the eyepiece because

the field will be too dark and you won't completely dark adapt in that environment.

 

Your best bet (my night sky is so bright it's actually light blue most of the time, here in L.A.) is to transport yourself and the scope to darker skies.

Depending on the LP environment, you may not have to travel far.  I'm in one of the brightest LP zones there is, and I only have to travel 85 miles to get to fairly dark skies.

You may be able to go much less distance and encounter dark skies.

Get in touch with the local astronomy club and find out where they go for star parties.  Chances are likely it's not that far.

https://www.skyandte...-organizations/

 

For viewing at home:

Moon

Planets

Double stars

Carbon stars

Bright star clusters

and, with a narrowband filter:

large bright nebulae like M42

the brighter planetary nebulae.

 

And leave galaxies, most nebulae, most star clusters, comets, and the Milky Way to your dark site viewing.


Edited by Starman1, 21 February 2019 - 11:05 PM.


#7 0R10N5

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Posted 22 February 2019 - 07:54 AM

Thanks for the great explanation, i really appreciate it. I will choose either Astronomik UHC or Orion Ultrablock.. I need to travel approx 50 miles to get a very dark site.

Thanks once again for that link, will look at it.


Edited by 0R10N5, 22 February 2019 - 07:58 AM.


#8 Stelios

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Posted 22 February 2019 - 02:15 PM

Let me echo Starman's appeal to transport yourself and the scope to darker skies. 

 

Really, you won't see anything much from skies such as you have, no matter what the filter. 

 

Be aware also that using an AP light pollution filter (such as the IDAS LP1 or the Orion Deep Sky Imaging Filter) will introduce color casts in your images that will make processing difficult. 

 

One night at a dark sky site is worth more than a month of imaging from a site such as in your picture. 

 

The exception is if you are doing narrowband imaging, with AP-specific filters such as Ha, Oiii and Sii. That *can* be (laboriously because of the Bayer matrix) done with a DSLR, but is much better suited to mono + filters CMOS or CCD cameras. Most people who image from sites such as yours do so with such cameras. 


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#9 0R10N5

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Posted 24 February 2019 - 01:48 AM

@ Stelios

 

In future i may try mono camera, that will be better option than DSLR. Currently i am new to AP so i decided to start with DSLR.



#10 TareqPhoto

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Posted 26 February 2019 - 03:14 PM

I ordered or placed an order yesterday for LP filter, said it is designed for LED LP in addition to yellow one [vapor sodium], so i can't wait until it is shipped and arrive here, it is an expensive one too, but i ordered it anyway, in fact i am planning to use it for my mono camera and all filters even NB ones, anything to cut LP even slightly, in 2 reviews of this filter they said that it was like a nightmare processing in LP without this filter, but when they used the filter it was easier to remove that issue in processing, so i am assuming this filter can have something to help, my sky LP isn't that bad at all, but LP is still an LP no matter how good or bad it is and i can't drive to a dark sites, it is not 50 miles away, it is like double of that and to us even 50 miles is like crossing the quarter distance of the whole country area [100 miles i can cross 3 main cities], so not interested for now [until i buy an economic car], but maybe you can't wait me until i get that filter in hand and test it, so good luck with your decisions.




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