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Need advice on a filter that handles LED lights

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#1 hdoraisamy

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Posted 19 September 2020 - 05:38 AM

I live in a Bortle 5 neighborhood with the nasty LED streetlights all across my community. I am trying to image nebulas and galaxies with my Canon EOS Rebel T6 + Pentax 130mm lens from my community.

I read that the IDAS LPS D2 filter handles LED lights well. But it is expensive.

Does anyone have any experience with this filter? Are there other filters that might help my scenarios? 

 

Thanks



#2 imtl

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Posted 19 September 2020 - 05:54 AM

LEDs emit broad band. Nothing can handle them.


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#3 TOMDEY

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Posted 19 September 2020 - 06:00 AM

The only filter that substantially helps is a car and a full tank of gas.    Tom


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#4 drd715

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Posted 19 September 2020 - 06:11 AM

Nebulas might be enhanced by imaging the Ha or dual band with a L- extreme filter, but your camera would have to be modified or replace with a cooled astro cam. Zwo has a new 4/3rds mono camera or the 533 and 2600 are good osc. You still get some of the led light pollution but 95% or more would be cut out. Galaxies are more broad band and not really narrow band targets.

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#5 Ittaku

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Posted 19 September 2020 - 07:03 AM

The only filter I've found that helps visualise DSOs (I don't image them) in the presence of almost exclusive LED illumination in bortle 8 skies here is the Astronomik UHC filter. Whether it's a good match for imaging, or there are better filters suited to it, I'm too inexperienced to say, but it definitely is able to bring out nebulae that are effectively invisible here.


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#6 hdoraisamy

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Posted 19 September 2020 - 07:24 AM

LEDs emit broad band. Nothing can handle them.

That's what i thought too, and then i saw this - Which is why i am wondering.

 

https://cloudbreakop...t=6275555196955



#7 Dynan

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Posted 19 September 2020 - 07:31 AM

Though expensive, an Optolong L-eXtreme filter may help. It does take advantage of some low peaks of broadband LED:

 

(Graphs are not same scale)

 

LED BW.jpg

 

LEXT BW.jpg


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#8 imtl

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Posted 19 September 2020 - 07:34 AM

But the link you gave shows the spectrum of LED with the filter you are asking about. You clearly see how much light pollution is allowed in. Galaxies are broad band. There is no filter for that. 

 

Nebulae are different story. You can use narrow band with mono or something like the L-extreme with OSC.



#9 Dynan

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Posted 19 September 2020 - 08:12 AM

The L-eXreme is not intended for galaxies. But gives good nebulae results even in Full Moon. Example:

 

https://www.cloudyni...extreme-filter/

 

All I was saying was, though expensive, it's better that nothing in bleached out LEDs. And TOMDEY is right...Gasoline is the best filter...but when you have nowhere to go...



#10 hdoraisamy

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Posted 19 September 2020 - 08:14 AM

But the link you gave shows the spectrum of LED with the filter you are asking about. You clearly see how much light pollution is allowed in. Galaxies are broad band. There is no filter for that. 

 

Nebulae are different story. You can use narrow band with mono or something like the L-extreme with OSC.

I see. If I wanted an exclusive filter for nebulae imaging using my DSLR, would a UHC filter work? Or should i stick to a more selective line filter? There are so many choices, its hard to decide



#11 imtl

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Posted 19 September 2020 - 09:12 AM

UHC is not really an imaging filter. Its for visual. Get an Ha filter and that will give you a good start.


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#12 hdoraisamy

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Posted 19 September 2020 - 09:23 AM

UHC is not really an imaging filter. Its for visual. Get an Ha filter and that will give you a good start.

Thank you!



#13 Tapio

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Posted 19 September 2020 - 09:48 AM

And you need to get your camera modified.

#14 hdoraisamy

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Posted 19 September 2020 - 10:09 AM

And you need to get your camera modified.

Is that a must? I have heard from people who say that modifying is not an absolute requirement. It is something that would be nice, but I don't think I have budget this year :(



#15 bobzeq25

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Posted 19 September 2020 - 10:11 AM

I live in a Bortle 5 neighborhood with the nasty LED streetlights all across my community. I am trying to image nebulas and galaxies with my Canon EOS Rebel T6 + Pentax 130mm lens from my community.

I read that the IDAS LPS D2 filter handles LED lights well. But it is expensive.

Does anyone have any experience with this filter? Are there other filters that might help my scenarios? 

 

Thanks

Gradient reduction in processing.  It identifies light pollution by spatial variation (worse at the horizon, better overhead), rather than take a meat axe approach of chopping out parts of the spectrum.   Works on all sources of light pollution, all targets.  A good tool is available in Astro Pixel Processor, and other astro specific processing programs.

 

Pretty much all serious imagers use gradient reduction.  Some will, in addition, use a broadband LP filter, some won't.  Pretty much all who do use them on emission nebulae only.

 

I see. If I wanted an exclusive filter for nebulae imaging using my DSLR, would a UHC filter work? Or should i stick to a more selective line filter? There are so many choices, its hard to decide

The new duo band and triband filters are quite popular, for good reason.  Designed for emission nebulae and one shot color cameras, they're a compromise between narrowband filters (which work well, but pretty much require a mono camera) and broadband LP filters.
 

Here's an inexpensive one.

 

https://www.highpoin...0bc750464e23899

 

But, as others have noted, an unmodified DSLR is poor for imaging emission nebulae, in any event.  It may not be "essential", but modifying your camera, or getting an astro specific camera (which is outside your budget) is more important than a filter.  The filter above won't do much on an unmodified camera.

 

In spite of their promising name, these filters are not very magical.  Sigh.


Edited by bobzeq25, 19 September 2020 - 10:13 AM.

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#16 imtl

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Posted 19 September 2020 - 10:11 AM

Not a must but unmoded will require a lot more integration time


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#17 hdoraisamy

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Posted 19 September 2020 - 10:23 AM

Thanks - I think i will start with a H-alpha clip on from Astronomik. I hope this will be a good start to seeing more contrast and details on objects such as M42



#18 bobzeq25

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Posted 19 September 2020 - 10:26 AM

Thanks - I think i will start with a H-alpha clip on from Astronomik. I hope this will be a good start to seeing more contrast and details on objects such as M42

Let us know how it works for you.  A large benefit of the forum is being able to pass on your experience to others in the same situation.


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#19 imtl

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Posted 19 September 2020 - 10:30 AM

Thanks - I think i will start with a H-alpha clip on from Astronomik. I hope this will be a good start to seeing more contrast and details on objects such as M42

M42 is a good start for unmoded DSLR since it is an extremely bright object. You'll do fine on it. Enjoy!


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#20 hdoraisamy

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Posted 19 September 2020 - 11:02 AM

Let us know how it works for you.  A large benefit of the forum is being able to pass on your experience to others in the same situation.

Will do!! Thank you all!



#21 daveco2

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Posted 19 September 2020 - 12:03 PM

Plot of LED and L-Enhance filter shows some benefit.

Attached Thumbnails

  • LED and L-enhance small.jpg


#22 bokemon

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Posted 19 September 2020 - 04:54 PM

Is that a must? I have heard from people who say that modifying is not an absolute requirement. It is something that would be nice, but I don't think I have budget this year frown.gif

It's more of a "you'll be sorry".  An unmodified camera only gets about 1/5th of the Ha light.
 


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#23 klaussius

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Posted 19 September 2020 - 05:12 PM

Is that a must? I have heard from people who say that modifying is not an absolute requirement. It is something that would be nice, but I don't think I have budget this year frown.gif


Depends on the model. Some models are almost blind to Ha without modification, and others have reduced but workable sensitivity.
 
So it's a YMMV case.

Edited by klaussius, 19 September 2020 - 05:13 PM.

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#24 17.5Dob

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Posted 19 September 2020 - 08:06 PM

Is that a must? I have heard from people who say that modifying is not an absolute requirement.

 

An "Absolute Requirement"...no. It depends on how much time you can reasonably put in.

Stock cameras vary between ~ 15%-25% Ha response, so plan on HAVING TO shoot 4X to 6X longer with a stock cam vs a modded cam.

From my Bortle 5 backyard, I need to shoot 7-8 MINUTE subs using an L-Enhance filter on my modded cam...I never shoot less than 3-1/2 hours and always try for 4 hrs + + total time...With a stock cam, you're going to need even longer subs and roughly 17hrs per target.....


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#25 hdoraisamy

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Posted 20 September 2020 - 01:43 PM

Thanks for the feedback on modification. My DSLR is used exclusively for astrophotography, so I don't have anything against modifying it. I was trying to figure out if the price point ($300 to modify) was worth it. I'll try to see if my unmodded camera gives me something that meets my requirements (more social media than anything else)

 

Related question - Is $300 a reasonable price to pay for modifying a camera? Or do you recommend just purchasing a used modded camera?




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