A question about light pollution filters.

[MalcolmD99]

Hi, I am doing some nightime landscape images and am wondering if I use a light pollution filter for the sky will this also cut off ambient light and moonlight on the landscape? Is it possible that light pollutions filters only cut out artificial light?

I want to ask befor I go out and buy a good filter.

Anyone have experience with this issue?

Thanks...

 

[RicksAstro]

Hi, I am doing some nightime landscape images and am wondering if I use a light pollution filter for the sky will this also cut off ambient light and moonlight on the landscape? Is it possible that light pollutions filters only cut out artificial light?

I want to ask befor I go out and buy a good filter.

Anyone have experience with this issue?

Thanks...

THere are many different light pollution filters, some better for retaining color balance, some better for cutting most light pollution. They are tuned to cut out common street building lights, like the sodium vapor lights.

But yes, they will cut out notches of wide bandwidth light like the moon and reflections, but will increase contrast in the scene.

Here's a great reference page:

https://www.sciencecenter.net/hutech/idas/lps.htm

 

[MalcolmD99]

Thanks for the info. It sounds like they have a similar affect as polorisers. Is that right?

i really don’t know what to look for but found this one one that says it reduces yellow sodium light. Do you think this one would work well?

Loading…

www.bhphotovideo.com

 

[Paul Barnard]

Hi, I am doing some nightime landscape images and am wondering if I use a light pollution filter for the sky will this also cut off ambient light and moonlight on the landscape? Is it possible that light pollutions filters only cut out artificial light?

I want to ask befor I go out and buy a good filter.

Anyone have experience with this issue?

Thanks...

Malcolm, your really going for Astro in a big way! I’m starting to tread the same path. Keep asking those questions it really helping me

 

[RicksAstro]

Thanks for the info. It sounds like they have a similar affect as polorisers. Is that right?

i really don’t know what to look for but found this one one that says it reduces yellow sodium light. Do you think this one would work well?

https://www.bhphotovideo.com/c/prod...yJCH3QIVD8pkCh1C_w8-EAQYAiABEgLy7fD_BwE&smp=y

Similar in the fact that they both cut down light, but completely different in how they do it and their effect.

The LP filter has coating on them that blocks certain wavelengths (like those associated with Sodium vapor streetlights), but lets other wavelengths through relatively unimpeded.

Polarizers impact all wavelengths equally but rather block waves of a certain polarization. So unless the light pollution was polarized, it wouldn't help it specifically at all.

The one from B&H looks like it could help.

 

[MalcolmD99]

I am attaching an example of the kind of light pollution I am dealing with. Although I am a long distance from the city there is a lot of light. Not all the pics are this extreme only when I point the camera in that direction. I mainly want to cut out light from the city in this kind of picture and in other situations where the light pollution is less intense and more evenly spread out I just want to be able to get darker skies so I can turn up the ISO to let me get a better exposure for the land. Any suggestions on what filter to buy?

Thanks...

 

[Beatsy]

I just bought an Astronomik CLS clip-filter for my A7rii. It stops the light pollution you show in your pic, and also "sky glow". At the cost of about a stop and a half of light, it lets you take longer exposures to suck up more starlight without also sucking up more light pollution. I haven't tried it yet because of the "new astro-equipment curse". There will be a month of cloudy nights in my area now...

The cool thing about this filter is that it clips inside the camera, in front of the sensor, so it can be used with any lens. Wide angle for Milky Way type shots, or longer lenses (or a telescope) on a tracking mount for closer views.

Got mine here

https://www.astroshop.eu/broadband-filters/astronomik-cls-sony-alpha-clip-filter/p,53729

Don't go for their "better" more expensive one. That's for deep-sky emission nebulae and filters out the stars too!

 

[Tristimulus]

Light pollution filters are intended for astrophotography where the sky is the object of interest. The light from sodium lamps and then some is suppressed and light from the rest of the spectrum pass trough the filter. Exposure tines must be increased compared to exposures without a light pollution filter.

The light from the moon is hardly affected by a light pollution filter as the moon is a full spectrum light source.

In my case I would not consider a light pollution filter unless doing tracked exposures of the night sky in a light polluted environment (a dark sky and no filter is far better).

Light pollution filters work best for longer focal lengths (the effect of the filter change with the angle of incidence). Something like a 1.4/24mm lens (popular for nightscapes and Milky Way photography) would give a very visible color shift towards the corners with a light pollution filter in front of the lens.

Light pollution filters can work well - but they are demanding!

 

[Berkrathes]

I just bought an Astronomik CLS clip-filter for my A7rii. It stops the light pollution you show in your pic, and also "sky glow". At the cost of about a stop and a half of light, it lets you take longer exposures to suck up more starlight without also sucking up more light pollution. I haven't tried it yet because of the "new astro-equipment curse". There will be a month of cloudy nights in my area now...

The cool thing about this filter is that it clips inside the camera, in front of the sensor, so it can be used with any lens. Wide angle for Milky Way type shots, or longer lenses (or a telescope) on a tracking mount for closer views.

Got mine here

https://www.astroshop.eu/broadband-filters/astronomik-cls-sony-alpha-clip-filter/p,53729

Don't go for their "better" more expensive one. That's for deep-sky emission nebulae and filters out the stars too!

On Fredmiranda someone posted about corner degradation with wideangle lenses in combination with this filter. Due to inccreased sensor stack.

Have you experienced something like this? otherwise it looks really interesting.

Thanks

Björn

 

[Beatsy]

I just bought an Astronomik CLS clip-filter for my A7rii. It stops the light pollution you show in your pic, and also "sky glow". At the cost of about a stop and a half of light, it lets you take longer exposures to suck up more starlight without also sucking up more light pollution. I haven't tried it yet because of the "new astro-equipment curse". There will be a month of cloudy nights in my area now...

The cool thing about this filter is that it clips inside the camera, in front of the sensor, so it can be used with any lens. Wide angle for Milky Way type shots, or longer lenses (or a telescope) on a tracking mount for closer views.

Got mine here

https://www.astroshop.eu/broadband-filters/astronomik-cls-sony-alpha-clip-filter/p,53729

Don't go for their "better" more expensive one. That's for deep-sky emission nebulae and filters out the stars too!

On Fredmiranda someone posted about corner degradation with wideangle lenses in combination with this filter. Due to inccreased sensor stack.

Have you experienced something like this? otherwise it looks really interesting.

Thanks

Björn

As I said, I haven't been able to use it yet thanks to the new astro-kit curse (clouds). But in anticipation of that exact issue I sent an enquiry to the seller before purchasing. They assured me (in writing) that it was not a problem. I actually don't believe them at all, but if it's really bad, I have a solid reason to send it back for a refund.

Once I finish up a few other projects, I plan to do a few "white wall" tests, just to see how bad it is. I'm hopeful that the LCC profiles (lens colour cast) in Capture One will offer an automated solution to fix RAW files before exporting for stacking. It's essentially just flat field correction as far as I can tell, but I can fix any other distortions simultaneously for a faster (and less onerous) workflow. Only need one profile per lens as they'll always be focussed at infinity. Fingers crossed...

 

[Beatsy]

Hi again,

I did a quick and dirty test and can confirm the Astronomik CLS clip filter adds no extra vignetting with Batis 2.8/18 (the widest I'm likely to use) or any of the Otuses (28, 55 and 85, all at f/1.4).

The filter adds a blue cast, as expected, but I took the opportunity to create LCC profiles in Capture One for each of the lenses mentioned. These remove both colour cast and lens-generated vignettes leaving perfectly corrected images. Nice - and very convenient to use (but only for wide-field star trail and Milky Way landscape stuff - probably).

It remains to be seen what happens to image quality on FF edges and corners. With the cloudy, rainy and misty weather here, I've got nothing at infinity to focus on right now - so that test can wait until the stars come out again...

BTW - the Sony Alpha version isn't so much a "clip filter" as a "push-fit filter". Nothing clicks into place, it just relies on a thin layer of dense foam that sticks out around the edges to "friction fit" in the opening. Seems very secure, but not sure how that will hold up to repeated insertion and removal. Time will tell...

Cheers

 

[Paul Barnard]

Hi again,

I did a quick and dirty test and can confirm the Astronomik CLS clip filter adds no extra vignetting with Batis 2.8/18 (the widest I'm likely to use) or any of the Otuses (28, 55 and 85, all at f/1.4).

The filter adds a blue cast, as expected, but I took the opportunity to create LCC profiles in Capture One for each of the lenses mentioned. These remove both colour cast and lens-generated vignettes leaving perfectly corrected images. Nice - and very convenient to use (but only for wide-field star trail and Milky Way landscape stuff - probably).

It remains to be seen what happens to image quality on FF edges and corners. With the cloudy, rainy and misty weather here, I've got nothing at infinity to focus on right now - so that test can wait until the stars come out again...

BTW - the Sony Alpha version isn't so much a "clip filter" as a "push-fit filter". Nothing clicks into place, it just relies on a thin layer of dense foam that sticks out around the edges to "friction fit" in the opening. Seems very secure, but not sure how that will hold up to repeated insertion and removal. Time will tell...

Cheers

I’ve ordered one to give it a try.

 

[PhilthePhrame]

https://improvephotography.com/51874/review-nisi-natural-night-filter/

You might also have a look at the NiSi Natural Night filter. I haven’t tried it yet, but I’m tempted.

 

[MalcolmD99]

Thanks...

 

[MalcolmD99]

I am just a little concerned that it will increase the likelihood of getting dust on the sensor. I usually try to change lenses as seldom as possible. Have you seen potential for this issue?

 

[Beatsy]

I am just a little concerned that it will increase the likelihood of getting dust on the sensor. I usually try to change lenses as seldom as possible. Have you seen potential for this issue?

Once it's in place it would vastly *decrease* the likelihood of dust - it blocks the entire aperture in front of the sensor.

 

[TravelForPictures]

I use the Hoya Red Intensifier aka Light Pollution Filter. It definitely helps when needed.

 

[MalcolmD99]

Well I guess if you are planning to leave it in that would be Okay. I would have to take it out for the many kinds of shots I do.

 

[MalcolmD99]

Thanks for the helpful information. Now I thinking maybe I should not use one much until I get a star tracker.

 

[RicksAstro]

Thanks for the helpful information. Now I thinking maybe I should not use one much until I get a star tracker.

I'd agree with that, unless you want to do star trail pics.

You really need the longer exposures to bring the dim Deep Sky objects (DSOs) out of the noise floor. Ironically, light polluted skies do allow shorter exposures, but the contrast between the pollution and the DSOs is very low and the light pollution is difficult to process out. You need to stack many shorter exposures to get something useful.

LP filters increase the contrast between pollution by reducing the Light Pollution more than the DSOs, but it still does reduce the light from the DSOs, requiring more exposure and thus tracking.